Sample records for thermal conductivity thermoelectric

  1. Glass-like thermal conductivity in high efficiency thermoelectric...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Glass-like thermal conductivity in high efficiency thermoelectric materials Glass-like thermal conductivity in high efficiency thermoelectric materials Discusses strategies to...

  2. Thermoelectric behavior of conducting polymers: On the possibility of off-diagonal thermoelectricity

    SciTech Connect (OSTI)

    Mateeva, N.; Niculescu, H.; Schlenoff, J.; Testardi, L.

    1997-07-01T23:59:59.000Z

    Non-cubic materials, when structurally aligned, possess sufficient anisotropy to exhibit thermoelectric effects where the electrical and thermal currents are orthogonal (off-diagonal thermoelectricity). The authors discuss the benefits of this form of thermoelectricity for devices and describe a search for suitable properties in the air-stable conducting polymers polyaniline and polypyrrole. They find the simple and general correlation that the logarithm of the electrical conductivity scales linearly with the Seebeck coefficient on doping but with proportionality in excess of the conventional prediction for thermoelectricity. The correlation is unexpected in its universality and unfavorable for thermoelectric applications. A simple model suggests that mobile charges of both signs exist in these polymers, and this leads to reduced thermoelectric efficiency. They also briefly discuss non air-stable polyacetylene, where ambipolar transport does not appear to occur, and where properties seem more favorable for thermoelectricity.

  3. Thermoelectric DC conductivities from black hole horizons

    E-Print Network [OSTI]

    Aristomenis Donos; Jerome P. Gauntlett

    2014-10-14T23:59:59.000Z

    An analytic expression for the DC electrical conductivity in terms of black hole horizon data was recently obtained for a class of holographic black holes exhibiting momentum dissipation. We generalise this result to obtain analogous expressions for the DC thermoelectric and thermal conductivities. We illustrate our results using some holographic Q-lattice black holes as well as for some black holes with linear massless axions, in both $D=4$ and $D=5$ bulk spacetime dimensions, which include both spatially isotropic and anisotropic examples. We show that some recently constructed ground states of holographic Q-lattices, which can be either electrically insulating or metallic, are all thermal insulators.

  4. Low thermal conductivity skutterudites

    SciTech Connect (OSTI)

    Fleurial, J.P.; Caillat, T.; Borshchevsky, A.

    1997-07-01T23:59:59.000Z

    Recent experimental results on semiconductors with the skutterudite crystal structure show that these materials possess attractive transport properties and have a good potential for achieving ZT values substantially larger than for state-of-the-art thermoelectric materials. Both n-type and p-type conductivity samples have been obtained, using several preparation techniques. Associated with a low hole effective mass, very high carrier mobilities, low electrical resistivities and moderate Seebeck coefficients are obtained in p-type skutterudites. For a comparable doping level, the carrier mobilities of n-type samples are about an order of magnitude lower than the values achieved on p-type samples. However, the much larger electron effective masses and Seebeck coefficients on p-type samples. However, the much larger electron effective masses and Seebeck coefficients make n-type skutterudite promising candidates as well. Unfortunately, the thermal conductivities of the binary skutterudites compounds are too large, particularly at low temperatures, to be useful for thermoelectric applications. Several approaches to the reduction of the lattice thermal conductivity in skutterudites are being pursued: heavy doping, formation of solid solutions and alloys, study of novel ternary and filled skutterudite compounds. All those approaches have already resulted in skutterudite compositions with substantially lower thermal conductivity values in these materials. Recently, superior thermoelectric properties in the moderate to high temperature range were achieved for compositions combining alloying and filling of the skutterudite structure. Experimental results and mechanisms responsible for low thermal conductivity in skutterudites are discussed.

  5. Thermal Strategies for High Efficiency Thermoelectric Power Generation...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Strategies for High Efficiency Thermoelectric Power Generation Thermal Strategies for High Efficiency Thermoelectric Power Generation Developing integrated TE system configurations...

  6. Thermoelectric Conductivities at Finite Magnetic Field and the Nernst Effect

    E-Print Network [OSTI]

    Keun-Young Kim; Kyung Kiu Kim; Yunseok Seo; Sang-Jin Sin

    2015-03-17T23:59:59.000Z

    We study electric, thermoelectric, and thermal conductivities of a strongly correlated system in the presence of magnetic field by gauge/gravity duality. We consider a general class of Einstein-Maxwell-Dilaton theory with axion fields imposing momentum relaxation. Analytic general formulas for DC conductivities and the Nernst signal are derived in terms of the black hole horizon data. For an explicit model study we analyse in detail the dyonic black hole modified by momentum relaxation. In this model, the Nernst signal shows a typical vortex-liquid effect when momentum relaxation effect is comparable to chemical potential. We compute all AC electric, thermoelectric, and thermal conductivities by numerical analysis and confirms that their zero frequency limits precisely reproduce our analytic formulas, which is a non-trivial consistency check of our methods. We discuss the momentum relaxation effect on conductivities including cyclotron resonance poles.

  7. Thermoelectric efficiency of three-terminal quantum thermal machines

    E-Print Network [OSTI]

    Francesco Mazza; Riccardo Bosisio; Giuliano Benenti; Vittorio Giovannetti; Rosario Fazio; Fabio Taddei

    2014-08-28T23:59:59.000Z

    The efficiency of a thermal engine working in linear response regime in a multi-terminals configuration is discussed. For the generic three-terminal case, we provide a general definition of local and non-local transport coefficients: electrical and thermal conductances, and thermoelectric powers. Within the Onsager formalism, we derive analytical expressions for the efficiency at maximum power, which can be written in terms of generalized figures of merit. Also, using two examples, we investigate numerically how a third terminal could improve the performance of a quantum system, and under which conditions non-local thermoelectric effects can be observed.

  8. Thermoelectric Conductivities at Finite Magnetic Field and the Nernst Effect

    E-Print Network [OSTI]

    Kim, Keun-Young; Seo, Yunseok; Sin, Sang-Jin

    2015-01-01T23:59:59.000Z

    We study electric, thermoelectric, and thermal conductivities of a strongly correlated system in the presence of magnetic field by gauge/gravity duality. We consider a general class of Einstein-Maxwell-Dilaton theory with axion fields imposing momentum relaxation. Analytic general formulas for DC conductivities and the Nernst signal are derived in terms of the black hole horizon data. For an explicit model study we analyse in detail the Dyonic black hole modified by momentum relaxation effect. In this model, the Nernst signal shows a typical vortex-liquid effect when momentum relaxation effect is comparable to chemical potential. We compute all AC electric, thermal, and thermal conductivities by numerical analysis and confirms that their zero frequency limits precisely reproduce our analytic formulas, which is a non-trivial consistency check of our methods. We discuss the momentum relaxation effect on conductivities including cyclotron frequencies.

  9. Optimal working conditions for thermoelectric generators with realistic thermal coupling

    E-Print Network [OSTI]

    Apertet, Y; Glavatskaya, O; Goupil, C; Lecoeur, P

    2011-01-01T23:59:59.000Z

    We study how maximum output power can be obtained from a thermoelectric generator(TEG) with nonideal heat exchangers. We demonstrate with an analytic approach based on a force-flux formalism that the sole improvement of the intrinsic characteristics of thermoelectric modules including the enhancement of the figure of merit is of limited interest: the constraints imposed by the working conditions of the TEG must be considered on the same footing. Introducing an effective thermal conductance we derive the conditions which permit maximization of both efficiency and power production of the TEG dissipatively coupled to heat reservoirs. Thermal impedance matching must be accounted for as well as electrical impedance matching in order to maximize the output power. Our calculations also show that the thermal impedance does not only depend on the thermal conductivity at zero electrical current: it also depends on the TEG figure of merit. Our analysis thus yields both electrical and thermal conditions permitting optima...

  10. Thermoelectric HVAC and Thermal Comfort Enablers for Light-Duty...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    and Thermal Comfort Enablers for Light-Duty Vehicle Applications Thermoelectric HVAC and Thermal Comfort Enablers for Light-Duty Vehicle Applications 2012 DOE Hydrogen and Fuel...

  11. Thermal conductivity and heat transfer in superlattices

    SciTech Connect (OSTI)

    Chen, G.; Neagu, M.; Borca-Tasciuc, T.

    1997-07-01T23:59:59.000Z

    Understanding the thermal conductivity and heat transfer processes in superlattice structures is critical for the development of thermoelectric materials and devices based on quantum structures. This work reports progress on the modeling of thermal conductivity of superlattice structures. Results from the models established based on the Boltzmann transport equation could explain existing experimental results on the thermal conductivity of semiconductor superlattices in both in plane and cross-plane directions. These results suggest the possibility of engineering the interfaces to further reduce thermal conductivity of superlattice structures.

  12. Characterizing the thermal efficiency of thermoelectric modules

    E-Print Network [OSTI]

    Phillips, Samuel S

    2009-01-01T23:59:59.000Z

    An experimental setup was designed and utilized to measure the thermoelectric properties as functions of temperature of a commercially available, bismuth telluride thermoelectric module. Thermoelectric modules are solid ...

  13. Dramatic thermal conductivity reduction by nanostructures for large increase in thermoelectric figure-of-merit of FeSb[subscript 2

    E-Print Network [OSTI]

    Chen, Gang

    In this report, thermal conductivity reduction by more than three orders of magnitude over its single crystal counterpart for the strongly correlated system FeSb[subscript 2] through a nanostructure approach was presented, ...

  14. Synthetic thermoelectric materials comprising phononic crystals

    DOE Patents [OSTI]

    El-Kady, Ihab F; Olsson, Roy H; Hopkins, Patrick; Reinke, Charles; Kim, Bongsang

    2013-08-13T23:59:59.000Z

    Synthetic thermoelectric materials comprising phononic crystals can simultaneously have a large Seebeck coefficient, high electrical conductivity, and low thermal conductivity. Such synthetic thermoelectric materials can enable improved thermoelectric devices, such as thermoelectric generators and coolers, with improved performance. Such synthetic thermoelectric materials and devices can be fabricated using techniques that are compatible with standard microelectronics.

  15. Tailoring the Thermoelectric Behavior of Electrically Conductive Polymer Composites

    E-Print Network [OSTI]

    Moriarty, Gregory P.

    2013-05-21T23:59:59.000Z

    the promise of fully organic composites as thermoelectric materials. This combination of CNT and stabilizer produced metallic electrical conductivity (200,000 S m-1) and power factors (S2?) within an order of magnitude of commonly used semiconductors (~400 ?W...

  16. Cluster expansion and optimization of thermal conductivity in SiGe nanowires M. K. Y. Chan,1,2

    E-Print Network [OSTI]

    Ceder, Gerbrand

    Cluster expansion and optimization of thermal conductivity in SiGe nanowires M. K. Y. Chan,1,2 J.20.dh, 63.22.Gh, 65.80. g I. INTRODUCTION A. SiGe nanowires for thermoelectric applications Minimizing for thermoelectric applications. Bulk SiGe alloys have been used for thermoelectric power generation for several de

  17. Enhanced Thermal Conductivity Oxide Fuels

    SciTech Connect (OSTI)

    Alvin Solomon; Shripad Revankar; J. Kevin McCoy

    2006-01-17T23:59:59.000Z

    the purpose of this project was to investigate the feasibility of increasing the thermal conductivity of oxide fuels by adding small fractions of a high conductivity solid phase.

  18. Thermal Conductivity of Coated Paper

    SciTech Connect (OSTI)

    Kerr, Lei L [ORNL; Pan, Yun-Long [Smart Papers, Hamilton, OH 45013; Dinwiddie, Ralph Barton [ORNL; Wang, Hsin [ORNL; Peterson, Robert C. [Miami University, Oxford, OH

    2009-01-01T23:59:59.000Z

    In this paper, we introduce a method for measuring the thermal conductivity of paper using a hot disk system. To the best of our knowledge, few publications are found discussing the thermal conductivity of a coated paper although it is important to various forms of today s digital printing where heat is used for imaging as well as for toner fusing. This motivates us to investigate the thermal conductivity of paper coating. Our investigation demonstrates that thermal conductivity is affected by the coat weight and the changes in the thermal conductivity affect ink gloss and density. As the coat weight increases, the thermal conductivity increases. Both the ink gloss and density decrease as the thermal conductivity increases. The ink gloss appears to be more sensitive to the changes in the thermal conductivity.

  19. Thermoelectric DC conductivities with momentum dissipation from higher derivative gravity

    E-Print Network [OSTI]

    Long Cheng; Xian-Hui Ge; Zu-Yao Sun

    2015-04-28T23:59:59.000Z

    We present a mechanism of momentum relaxation in higher derivative gravity by adding linear scalar fields to the Gauss-Bonnet theory. We analytically computed all of the DC thermoelectric conductivities in this theory by adopting the method given by Donos and Gauntlett in [arXiv:1406.4742]. The results show that the DC electric conductivity is not a monotonic function of the effective impurity parameter $\\beta$: in the small $\\beta$ limit, the DC conductivity is dominated by the coherent phase, while for larger $\\beta$, pair creation contribution to the conductivity becomes dominant, signaling an incoherent phase. In addition, the DC heat conductivity is found independent of the Gauss-Bonnet coupling constant.

  20. Thermal Conduction in Aligned Carbon Nanotube–Polymer Nanocomposites with High Packing Density

    E-Print Network [OSTI]

    Marconnet, Amy M.

    Nanostructured composites containing aligned carbon nanotubes (CNTs) are very promising as interface materials for electronic systems and thermoelectric power generators. We report the first data for the thermal conductivity ...

  1. Cluster expansion and optimization of thermal conductivity in SiGe nanowires

    E-Print Network [OSTI]

    Chan, Maria K.

    We investigate the parametrization and optimization of thermal conductivity in silicon-germanium alloy nanowires by the cluster-expansion technique. Si1?xGex nanowires are of interest for thermoelectric applications and ...

  2. Thermal conductivity of thermal-battery insulations

    SciTech Connect (OSTI)

    Guidotti, R.A.; Moss, M.

    1995-08-01T23:59:59.000Z

    The thermal conductivities of a variety of insulating materials used in thermal batteries were measured in atmospheres of argon and helium using several techniques. (Helium was used to simulate the hydrogen atmosphere that results when a Li(Si)/FeS{sub 2} thermal battery ages.) The guarded-hot-plate method was used with the Min-K insulation because of its extremely low thermal conductivity. For comparison purposes, the thermal conductivity of the Min-K insulating board was also measured using the hot-probe method. The thermal-comparator method was used for the rigid Fiberfrax board and Fiberfrax paper. The thermal conductivity of the paper was measured under several levels of compression to simulate the conditions of the insulating wrap used on the stack in a thermal battery. The results of preliminary thermal-characterization tests with several silica aerogel materials are also presented.

  3. Design of bulk thermoelectric modules for integrated circuit thermal management

    E-Print Network [OSTI]

    Fukutani, K; Shakouri, A

    2006-01-01T23:59:59.000Z

    cooling enhancement with thermoelectric coolers,” Trans.M. S. Dresselhaus, “Thermoelectric ?gure of merit of a one-A. Shakouri, “Improved thermoelectric power factor in metal-

  4. Material compatibility and thermal aging of thermoelectric materials.

    SciTech Connect (OSTI)

    Gardea, Andrew D.; Nishimoto, Ryan; Yang, Nancy Y. C.; Morales, Alfredo Martin; Whalen, Scott A.; Chames, Jeffrey M.; Clift, W. Miles

    2009-09-01T23:59:59.000Z

    In order to design a thermoelectric (TE) module suitable for long-term elevated temperature use, the Department 8651 has conducted parametric experiments to study material compatibility and thermal aging of TE materials. In addition, a comprehensive material characterization has been preformed to examine thermal stability of P- and N-based alloys and their interaction with interconnect diffusion barrier(s) and solder. At present, we have completed the 7-days aging experiments for 36 tiles, from ambient to 250 C. The thermal behavior of P- and N-based alloys and their thermal interaction with both Ni and Co diffusion barriers and Au-Sn solder were examined. The preliminary results show the microstructure, texture, alloy composition, and hardness of P-(Bi,Sb){sub 2}Te{sub 3} and N-Bi{sub 2}(Te,Se){sub 3} alloys are thermally stable up to 7 days annealing at 250 C. However, metallurgical reactions between the Ni-phosphor barriers and P-type base alloy were evident at temperatures {ge} 175 C. At 250 C, the depth (or distance) of the metallurgical reaction and/or Ni diffusion into P-(Bi,Sb){sub 2}Te{sub 3} is approximately 10-15 {micro}m. This thermal instability makes the Ni-phosphor barrier unsuitable for use at temperatures {ge} 175 C. The Co barrier appeared to be thermally stable and compatible with P(Bi,Sb){sub 2}Te{sub 3} at all annealing temperatures, with the exception of a minor Co diffusion into Au-Sn solder at {ge} 175 C. The effects of Co diffusion on long-term system reliability and/or the thermal stability of the Co barrier are yet to be determined. Te evaporation and its subsequent reaction with Au-Sn solder and Ni and Co barriers on the ends of the tiles at temperatures {ge} 175 C were evident. The Te loss and its effect on the long-term required stoichiometry of P-(Bi, Sb){sub 2}Te{sub 3} are yet to be understood. The aging experiments of 90 days and 180 days are ongoing and scheduled to be completed in 30 days and 150 days, respectively. Material characterization activities are continuing for the remaining tiles.

  5. Atomistic calculations of the electronic, thermal, and thermoelectric properties of ultra-thin Si layers

    E-Print Network [OSTI]

    1 Atomistic calculations of the electronic, thermal, and thermoelectric properties of ultra-thin Si are considered promising candidates for thermoelectric applications with enhanced performance because. This is also the case for traditionally poor thermoelectric materials such as silicon. This work presents

  6. Cermet fuel thermal conductivity 

    E-Print Network [OSTI]

    Alvis, John Mark

    1988-01-01T23:59:59.000Z

    particles of low conductivity dispersed in a metal matrix of high conductivity. A computer code was developed in order to compute the conductivity of cermet fuels as predicted by existing models and an additional model derived in this work... gas release from the fuel particle and contact resistance at the fuel-matrix interface. A description of the methodology used to construct the model is given in Chapter 3. Comparisons between the analytic predictions and the experimental data...

  7. A high-pressure route to thermoelectrics with low thermal conductivity: The solid solution series AgIn{sub x}Sb{sub 1?x}Te{sub 2} (x=0.1–0.6)

    SciTech Connect (OSTI)

    Schröder, Thorsten; Rosenthal, Tobias; Souchay, Daniel; Petermayer, Christian; Grott, Sebastian [LMU Munich, Department of Chemistry, Butenandtstraße 5-13 (D), 81377 Munich (Germany); Scheidt, Ernst-Wilhelm; Gold, Christian; Scherer, Wolfgang [University of Augsburg, Institut für Physik, Universitätsstraße 1, 86159 Augsburg (Germany); Oeckler, Oliver, E-mail: oliver.oeckler@gmx.de [Leipzig University, IMKM, Scharnhorststraße 20, 04275 Leipzig (Germany)

    2013-10-15T23:59:59.000Z

    Metastable rocksalt-type phases of the solid solution series AgIn{sub x}Sb{sub 1?x}Te{sub 2} (x=0.1, 0.2, 0.4, 0.5 and 0.6) were prepared by high-pressure synthesis at 2.5 GPa and 400 °C. In these structures, the coordination number of In{sup 3+} is six, in contrast to chalcopyrite ambient-pressure AgInTe{sub 2} with fourfold In{sup 3+} coordination. Transmission electron microscopy shows that real-structure phenomena and a certain degree of short-range order are present, yet not very pronounced. All three cations are statistically disordered. The high degree of disorder is probably the reason why AgIn{sub x}Sb{sub 1?x}Te{sub 2} samples with 0.4thermal conductivities with a total ?<0.5 W/K m and a lattice contribution of ?{sub ph} ?0.3 W/K m at room temperature. These are lower than those of other rocksalt-type tellurides at room temperature; e.g. the well-known thermoelectric AgSbTe{sub 2} (? ?0.6 W/K m). The highest ZT value (0.15 at 300 K) is observed for AgIn{sub 0.5}Sb{sub 0.5}Te{sub 2}, mainly due to its high Seebeck coefficient of 160 µV/K. Temperature-dependent X-ray powder patterns indicate that the solid solutions are metastable at ambient pressure. At 150 °C, the quaternary compounds decompose into chalcopyrite-type AgInTe{sub 2} and rocksalt-type AgSbTe{sub 2}. - Graphical abstract: Reaction scheme, temperature characteristics of the ZT value and a selected-area electron diffraction pattern (background) of AgIn{sub 0.5}Sb{sub 0.5}Te{sub 2}, which crystallizes in a rocksalt-type structure with statistical cation disorder. Display Omitted - Highlights: • High-pressure synthesis yields the novel solid solution series AgIn{sub x}Sb{sub 1?x}Te{sub 2}. • In contrast to AgInTe{sub 2}, the compounds are inert at ambient pressure. • HRTEM shows no pronounced short-range order in the disordered NaCl-type structure. • The metastable phases exhibit very low total thermal conductivities <0.5 W/K m. • ZT values of 0.15 at room temperature were measured for AgIn{sub 0.5}Sb{sub 0.5}Te{sub 2}.

  8. An International Round-Robin Study, Part II: Thermal Diffusivity, Specific Heat and Thermal Conductivity

    SciTech Connect (OSTI)

    Wang, Hsin [ORNL; Porter, Wallace D [ORNL; Bottner, Harold [Fraunhofer-Institute, Freiburg, Germany; Konig, Jan [Fraunhofer-Institute, Freiburg, Germany; Chen, Lidong [Chinese Academy of Sciences; Bai, Shengqiang [Chinese Academy of Sciences; Tritt, Terry M. [Clemson University; Mayolett, Alex [Corning, Inc; Senawiratne, Jayantha [Corning, Inc; Smith, Charlene [Corning, Inc; Harris, Fred [ZT-Plus; Gilbert, Partricia [Marlow Industries, Inc; Sharp, J [Marlow Industries, Inc; Lo, Jason [CANMET - Materials Technology Laboratory, Natural Resources of Canada; Keinke, Holger [University of Waterloo, Canada; Kiss, Laszlo I. [University of Quebec at Chicoutimi

    2013-01-01T23:59:59.000Z

    For bulk thermoelectrics, figure-of-merit, ZT, still needs to improve from the current value of 1.0 - 1.5 to above 2 to be competitive to other alternative technologies. In recent years, the most significant improvements in ZT were mainly due to successful reduction of thermal conductivity. However, thermal conductivity cannot be measured directly at high temperatures. The combined measurements of thermal diffusivity and specific heat and density are required. It has been shown that thermal conductivity is the property with the greatest uncertainty and has a direct influence on the accuracy of the figure of merit. The International Energy Agency (IEA) group under the implementing agreement for Advanced Materials for Transportation (AMT) has conducted two international round-robins since 2009. This paper is Part II of the international round-robin testing of transport properties of bulk bismuth telluride. The main focuses in Part II are on thermal diffusivity, specific heat and thermal conductivity.

  9. Cermet fuel thermal conductivity

    E-Print Network [OSTI]

    Alvis, John Mark

    1988-01-01T23:59:59.000Z

    ? ) is expressed by k ( + + ) (3 21) where llg? gap conductance (W/mz-'K) kg? ? conductivity of the gas mixture (W/m-'K) d = actual gap dimension (m) gt gz= temperature jump distances at the fuel and cladding surfaces (cm) The value of d in Equation 3. 21...- ?, )+ ( ") 3 (I- ?, ) - ( ? ) 3 1 yvM trMT b 1+ vF g?T a 1-v?a 1-vF (3. 31) and finally, 2aFBF T 2EMC3M 1 1-2va 1-va 1+vM a (3, 32) 21 Once the constants have been determined, Equation 3. 28 can be solved at the fuel particle outer radius to determine...

  10. High-precision thermal and electrical characterization of thermoelectric modules

    SciTech Connect (OSTI)

    Kolodner, Paul [Bell Laboratories, Alcatel-Lucent, Inc., Murray Hill, New Jersey 07974 (United States)] [Bell Laboratories, Alcatel-Lucent, Inc., Murray Hill, New Jersey 07974 (United States)

    2014-05-15T23:59:59.000Z

    This paper describes an apparatus for performing high-precision electrical and thermal characterization of thermoelectric modules (TEMs). The apparatus is calibrated for operation between 20?°C and 80?°C and is normally used for measurements of heat currents in the range 0–10 W. Precision thermometry based on miniature thermistor probes enables an absolute temperature accuracy of better than 0.010?°C. The use of vacuum isolation, thermal guarding, and radiation shielding, augmented by a careful accounting of stray heat leaks and uncertainties, allows the heat current through the TEM under test to be determined with a precision of a few mW. The fractional precision of all measured parameters is approximately 0.1%.

  11. Thermal Conductivity of Polycrystalline Semiconductors and Ceramics

    E-Print Network [OSTI]

    Wang, Zhaojie

    2012-01-01T23:59:59.000Z

    RTG refers to radioisotope thermoelectric generator with aRTG refers to radioisotope thermoelectric generator with a

  12. Modeling of solar thermal selective surfaces and thermoelectric generators

    E-Print Network [OSTI]

    McEnaney, Kenneth

    2010-01-01T23:59:59.000Z

    A thermoelectric generator is a solid-state device that converts a heat flux into electrical power via the Seebeck effect. When a thermoelectric generator is inserted between a solar-absorbing surface and a heat sink, a ...

  13. Analytical thermal model validation for Cassini radioisotope thermoelectric generator

    SciTech Connect (OSTI)

    Lin, E.I. [California Inst. of Tech., Pasadena, CA (United States). Jet Propulsion Lab.

    1997-12-31T23:59:59.000Z

    The Saturn-bound Cassini spacecraft is designed to rely, without precedent, on the waste heat from its three radioisotope thermoelectric generators (RTGs) to warm the propulsion module subsystem, and the RTG end dome temperature is a key determining factor of the amount of waste heat delivered. A previously validated SINDA thermal model of the RTG was the sole guide to understanding its complex thermal behavior, but displayed large discrepancies against some initial thermal development test data. A careful revalidation effort led to significant modifications and adjustments of the model, which result in a doubling of the radiative heat transfer from the heat source support assemblies to the end domes and bring up the end dome and flange temperature predictions to within 2 C of the pertinent test data. The increased inboard end dome temperature has a considerable impact on thermal control of the spacecraft central body. The validation process offers an example of physically-driven analytical model calibration with test data from not only an electrical simulator but also a nuclear-fueled flight unit, and has established the end dome temperatures of a flight RTG where no in-flight or ground-test data existed before.

  14. Molecular Level Assessment of Thermal Transport and Thermoelectricity in Materials: From Bulk Alloys to Nanostructures 

    E-Print Network [OSTI]

    Kinaci, Alper

    2013-05-02T23:59:59.000Z

    applications. Carbon- and boron nitride-based nanomaterials also offer new opportunities in many applications from thermoelectrics to fast heat removers. For these materials, molecular dynamics calculations are used to evaluate lattice thermal transport. To do...

  15. High performance thermoelectric nanocomposite device

    DOE Patents [OSTI]

    Yang, Jihui (Lakeshore, CA); Snyder, Dexter D. (Birmingham, MI)

    2011-10-25T23:59:59.000Z

    A thermoelectric device includes a nanocomposite material with nanowires of at least one thermoelectric material having a predetermined figure of merit, the nanowires being formed in a porous substrate having a low thermal conductivity and having an average pore diameter ranging from about 4 nm to about 300 nm.

  16. Navier-Stokes on Black Hole Horizons and DC Thermoelectric Conductivity

    E-Print Network [OSTI]

    Aristomenis Donos; Jerome P. Gauntlett

    2015-06-04T23:59:59.000Z

    We consider a general class of black hole solutions of Einstein-Maxwell theory which are holographically dual to CFTs with spatially dependent sources. We show that an averaged DC thermoelectric conductivity matrix can be obtained by solving the forced, linearised, time-independent Navier-Stokes equations on the black hole horizon for an incompressible and charged fluid.

  17. Navier-Stokes on Black Hole Horizons and DC Thermoelectric Conductivity

    E-Print Network [OSTI]

    Donos, Aristomenis

    2015-01-01T23:59:59.000Z

    We consider a general class of black hole solutions of Einstein-Maxwell theory which are holographically dual to CFTs with spatially dependent sources. We show that an averaged DC thermoelectric conductivity matrix can be obtained by solving the forced, linearised, time-independent Navier-Stokes equations on the black hole horizon for an incompressible and charged fluid.

  18. Thermal conductivity of sputtered amorphous Ge films

    SciTech Connect (OSTI)

    Zhan, Tianzhuo; Xu, Yibin; Goto, Masahiro; Tanaka, Yoshihisa; Kato, Ryozo; Sasaki, Michiko; Kagawa, Yutaka [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan)] [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan)

    2014-02-15T23:59:59.000Z

    We measured the thermal conductivity of amorphous Ge films prepared by magnetron sputtering. The thermal conductivity was significantly higher than the value predicted by the minimum thermal conductivity model and increased with deposition temperature. We found that variations in sound velocity and Ge film density were not the main factors in the high thermal conductivity. Fast Fourier transform patterns of transmission electron micrographs revealed that short-range order in the Ge films was responsible for their high thermal conductivity. The results provide experimental evidences to understand the underlying nature of the variation of phonon mean free path in amorphous solids.

  19. Critical Behavior of the Thermoelectric Transport Properties in Amorphous Systems

    E-Print Network [OSTI]

    Chemnitz, Technische Universität

    Critical Behavior of the Thermoelectric Transport Properties in Amorphous Systems near the Metal., London SW7 2BZ, U.K. Abstract The scaling behavior of the thermoelectric trans- port properties;, the thermoelectric power S, the thermal conductivity K and the Lorenz number L0 obey scaling. The scaling description

  20. Tailoring the Thermoelectric Behavior of Electrically Conductive Polymer Composites 

    E-Print Network [OSTI]

    Moriarty, Gregory P.

    2013-05-21T23:59:59.000Z

    fabrication temperatures. These concerns have led research efforts into electrically conductive polymer composites prepared in ambient conditions from aqueous solutions. By combining polymer latex with carbon nanotubes (CNT), electrical conductivity can...

  1. High-density thermoelectric power generation and nanoscale thermal metrology

    E-Print Network [OSTI]

    Mayer, Peter (Peter Matthew), 1978-

    2007-01-01T23:59:59.000Z

    Thermoelectric power generation has been around for over 50 years but has seen very little large scale implementation due to the inherently low efficiencies and powers available from known materials. Recent material advances ...

  2. Effective Thermal Conductivity of Graded Nanocomposites with Interfacial Thermal

    E-Print Network [OSTI]

    Paulino, Glaucio H.

    Effective Thermal Conductivity of Graded Nanocomposites with Interfacial Thermal Resistance H Engineering, Newmark Laboratory, 205 North Mathews Avenue, University of Illinois at Urbana-Champaign, Urbana, IL 61801 Department of Civil and Environmental Engineering, 4139 Engineering Gateway, University

  3. Experimental thermal conductivity and contact conductance of graphite composites 

    E-Print Network [OSTI]

    Jackson, Marian Christine

    1998-01-01T23:59:59.000Z

    Graphite fiber organic matrix composites were reviewed ics. for potential heat sink applications in the electronics packaging determined the effective transverse and longitudinal thermal industry. This experimental investigation conductivity...

  4. Experimental thermal conductivity and contact conductance of graphite composites

    E-Print Network [OSTI]

    Jackson, Marian Christine

    1998-01-01T23:59:59.000Z

    Graphite fiber organic matrix composites were reviewed ics. for potential heat sink applications in the electronics packaging determined the effective transverse and longitudinal thermal industry. This experimental investigation conductivity...

  5. Thermal conductivity of Zn{sub 4{minus}x}Cd{sub x}Sb{sub 3} solid solutions

    SciTech Connect (OSTI)

    Caillat, T.; Borshchevsky, A.; Fleurial, J.P.

    1997-07-01T23:59:59.000Z

    {beta}-Zn{sub 4}Sb{sub 3} was recently identified at the Jet Propulsion Laboratory as a new high performance p-type thermoelectric material with a maximum dimensionless thermoelectric figure of merit ZT of 1.4 at a temperature of 673K. A usual approach, used for many state-of-the-art thermoelectric materials, to further improve ZT values is to alloy {beta}-Zn{sub 4}Sb{sub 3} with isostructural compounds because of the expected decrease in lattice thermal conductivity. The authors have grown Zn{sub 4{minus}x}Cd{sub x}Sb{sub 3} crystals with 0.2 {le} x < 1.2 and measured their thermal conductivity from 10 to 500K. The thermal conductivity values of Zn{sub 4{minus}x}Cd{sub x}Sb{sub 3} alloys are significantly lower than those measured for {beta}-Zn{sub 4}Sb{sub 3} and are comparable to its calculated minimum thermal conductivity. A strong atomic disorder is believed to be primarily at the origin of the very low thermal conductivity of these materials which are also fairly good electrical conductors and are therefore excellent candidates for thermoelectric applications.

  6. High Energy Density Thermal Batteries: Thermoelectric Reactors for Efficient Automotive Thermal Storage

    SciTech Connect (OSTI)

    None

    2011-11-15T23:59:59.000Z

    HEATS Project: Sheetak is developing a new HVAC system to store the energy required for heating and cooling in EVs. This system will replace the traditional refrigerant-based vapor compressors and inefficient heaters used in today’s EVs with efficient, light, and rechargeable hot-and-cold thermal batteries. The high energy density thermal battery—which does not use any hazardous substances—can be recharged by an integrated solid-state thermoelectric energy converter while the vehicle is parked and its electrical battery is being charged. Sheetak’s converters can also run on the electric battery if needed and provide the required cooling and heating to the passengers—eliminating the space constraint and reducing the weight of EVs that use more traditional compressors and heaters.

  7. Thermoelectrics Combined with Solar Concentration for Electrical and Thermal Cogeneration

    E-Print Network [OSTI]

    Jackson, Philip Robert

    2012-01-01T23:59:59.000Z

    significant challenge for solar thermal energy generation issolar thermal, cogeneration of electrical and thermal energy,for efficient energy production. Solar thermal plants, such

  8. Thermal conductivity measurements of Summit polycrystalline silicon.

    SciTech Connect (OSTI)

    Clemens, Rebecca; Kuppers, Jaron D.; Phinney, Leslie Mary

    2006-11-01T23:59:59.000Z

    A capability for measuring the thermal conductivity of microelectromechanical systems (MEMS) materials using a steady state resistance technique was developed and used to measure the thermal conductivities of SUMMiT{trademark} V layers. Thermal conductivities were measured over two temperature ranges: 100K to 350K and 293K to 575K in order to generate two data sets. The steady state resistance technique uses surface micromachined bridge structures fabricated using the standard SUMMiT fabrication process. Electrical resistance and resistivity data are reported for poly1-poly2 laminate, poly2, poly3, and poly4 polysilicon structural layers in the SUMMiT process from 83K to 575K. Thermal conductivity measurements for these polysilicon layers demonstrate for the first time that the thermal conductivity is a function of the particular SUMMiT layer. Also, the poly2 layer has a different variation in thermal conductivity as the temperature is decreased than the poly1-poly2 laminate, poly3, and poly4 layers. As the temperature increases above room temperature, the difference in thermal conductivity between the layers decreases.

  9. An Innovative High Thermal Conductivity Fuel Design

    SciTech Connect (OSTI)

    Jamil A. Khan

    2009-11-21T23:59:59.000Z

    Thermal conductivity of the fuel in today's Light Water Reactors, Uranium dioxide, can be improved by incorporating a uniformly distributed heat conducting network of a higher conductivity material, Silicon Carbide. The higher thermal conductivity of SiC along with its other prominent reactor-grade properties makes it a potential material to address some of the related issues when used in UO2 [97% TD]. This ongoing research, in collaboration with the University of Florida, aims to investigate the feasibility and develop a formal methodology of producing the resultant composite oxide fuel. Calculations of effective thermal conductivity of the new fuel as a function of %SiC for certain percentages and as a function of temperature are presented as a preliminary approach. The effective thermal conductivities are obtained at different temperatures from 600K to 1600K. The corresponding polynomial equations for the temperature-dependent thermal conductivities are given based on the simulation results. Heat transfer mechanism in this fuel is explained using a finite volume approach and validated against existing empirical models. FLUENT 6.1.22 was used for thermal conductivity calculations and to estimate reduction in centerline temperatures achievable within such a fuel rod. Later, computer codes COMBINE-PC and VENTURE-PC were deployed to estimate the fuel enrichment required, to maintain the same burnup levels, corresponding to a volume percent addition of SiC.

  10. Increased thermal conductivity monolithic zeolite structures

    DOE Patents [OSTI]

    Klett, James (Knoxville, TN); Klett, Lynn (Knoxville, TN); Kaufman, Jonathan (Leonardtown, MD)

    2008-11-25T23:59:59.000Z

    A monolith comprises a zeolite, a thermally conductive carbon, and a binder. The zeolite is included in the form of beads, pellets, powders and mixtures thereof. The thermally conductive carbon can be carbon nano-fibers, diamond or graphite which provide thermal conductivities in excess of about 100 W/mK to more than 1,000 W/mK. A method of preparing a zeolite monolith includes the steps of mixing a zeolite dispersion in an aqueous colloidal silica binder with a dispersion of carbon nano-fibers in water followed by dehydration and curing of the binder is given.

  11. Electrical and thermal conductivities in dense plasmas

    SciTech Connect (OSTI)

    Faussurier, G., E-mail: gerald.faussurier@cea.fr; Blancard, C.; Combis, P.; Videau, L. [CEA, DAM, DIF, F-91297 Arpajon (France)

    2014-09-15T23:59:59.000Z

    Expressions for the electrical and thermal conductivities in dense plasmas are derived combining the Chester-Thellung-Kubo-Greenwood approach and the Kramers approximation. The infrared divergence is removed assuming a Drude-like behaviour. An analytical expression is obtained for the Lorenz number that interpolates between the cold solid-state and the hot plasma phases. An expression for the electrical resistivity is proposed using the Ziman-Evans formula, from which the thermal conductivity can be deduced using the analytical expression for the Lorenz number. The present method can be used to estimate electrical and thermal conductivities of mixtures. Comparisons with experiment and quantum molecular dynamics simulations are done.

  12. Thermal conductivity of bulk nanostructured lead telluride

    SciTech Connect (OSTI)

    Hori, Takuma [Department of Mechanical Engineering, The University of Tokyo, Bunkyo, Tokyo 113-8656 (Japan); Chen, Gang [Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Shiomi, Junichiro, E-mail: shiomi@photon.t.u-tokyo.ac.jp [Department of Mechanical Engineering, The University of Tokyo, Bunkyo, Tokyo 113-8656 (Japan); PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012 (Japan)

    2014-01-13T23:59:59.000Z

    Thermal conductivity of lead telluride with embedded nanoinclusions was studied using Monte Carlo simulations with intrinsic phonon transport properties obtained from first-principles-based lattice dynamics. The nanoinclusion/matrix interfaces were set to completely reflect phonons to model the maximum interface-phonon-scattering scenario. The simulations with the geometrical cross section and volume fraction of the nanoinclusions matched to those of the experiment show that the experiment has already reached the theoretical limit of thermal conductivity. The frequency-dependent analysis further identifies that the thermal conductivity reduction is dominantly attributed to scattering of low frequency phonons and demonstrates mutual adaptability of nanostructuring and local disordering.

  13. Multiple-Filled Skutterudites: High Thermoelectric Figure of Merit through Separately Optimizing Electrical and Thermal Transports

    SciTech Connect (OSTI)

    Zhang, Weiqing [Chinese Academy of Sciences; Yang, Jiong [Chinese Academy of Sciences; Yang, Jihui [General Motors Corporation; Wang, Hsin [ORNL; Salvador, James R. [GM R& D and Planning, Warren, Michigan; Shi, Xun [General Motors Corporation-R& D; Chi, Miaofang [ORNL; Cho, Jung Y [GM R& D and Planning, Warren, Michigan; Bai, Shengqiang [Chinese Academy of Sciences; Chen, Lidong [Chinese Academy of Sciences

    2011-01-01T23:59:59.000Z

    Skutterudites CoSb{sub 3} with multiple cofillers Ba, La, and Yb were synthesized and very high thermoelectric figure of merit ZT = 1.7 at 850 K was realized. X-ray diffraction of the densified multiple-filled bulk samples reveals all samples are phase pure. High-resolution scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDS) analysis confirm that multiple guest fillers occupy the nanoscale-cages in the skutterudites. The fillers are further shown to be uniformly distributed and the Co-Sb skutterudite framework is virtually unperturbed from atomic scale to a few micrometers. Our results firmly show that high power factors can be realized by adjusting the total filling fraction of fillers with different charge states to reach the optimum carrier density, at the same time, lattice thermal conductivity can also be significantly reduced, to values near the glass limit of these materials, through combining filler species of different rattling frequencies to achieve broad-frequency phonon scattering. Therefore, partially filled skutterudites with multiple fillers of different chemical nature render unique structural characteristics for optimizing electrical and thermal transports in a relatively independent way, leading to continually enhanced ZT values from single- to double-, and finally to multiple-filled skutterudites. The idea of combining multiple fillers with different charge states and rattling frequencies for performance optimization is also expected to be valid for other caged TE compounds.

  14. The potential impact of ZT=4 thermoelectric materials on solar thermal energy conversion technologies.

    SciTech Connect (OSTI)

    Xie, M.; Gruen, D. M.; Materials Science Division; Michigan Technological Univ.

    2010-03-02T23:59:59.000Z

    State-of-the-art methodologies for the conversion of solar thermal power to electricity are based on conventional electromagnetic induction techniques. If appropriate ZT = 4 thermoelectric materials were available, it is likely that conversion efficiencies of 30-40% could be achieved. The availability of all solid state electricity generation would be a long awaited development in part because of the elimination of moving parts. This paper presents a preliminary examination of the potential performance of ZT = 4 power generators in comparison with Stirling engines taking into account specific mass, volume and cost as well as system reliability. High-performance thermoelectrics appear to have distinct advantages over magnetic induction technologies.

  15. Thermal Conductivity of Ordered Molecular Water

    SciTech Connect (OSTI)

    W Evans; J Fish; P Keblinski

    2006-02-16T23:59:59.000Z

    We use molecular dynamics simulation to investigate thermal transport characteristics of water with various degree of orientational and translational order induced by the application of an electric field. We observe that orientational ordering of the water dipole moments has a minor effect on the thermal conductivity. However, electric-field induced crystallization and associated translational order results in approximately a 3-fold increase of thermal conductivity with respect to the base water, i.e., to values comparable with those characterizing ice crystal structures.

  16. Modeling of the Thermoelectric Properties of Quasi-One-Dimensional Organic Semiconductors , A.A. Balandin2

    E-Print Network [OSTI]

    Modeling of the Thermoelectric Properties of Quasi-One-Dimensional Organic Semiconductors A. Casian Electrical conductivity , Seebeck coefficient S, electronic thermal conductivity e and the thermoelectric the general principles of solid state physics there is no upper limit for the thermoelectric figure of merit

  17. Measuring Thermal Transport in Extreme Environments: Thermal Conductivity

    E-Print Network [OSTI]

    Braun, Paul

    Chen California Institute of Technology Jackie Li University of Michigan supported by CarnegieMeasuring Thermal Transport in Extreme Environments: Thermal Conductivity of Water Ice VII to 20 GPa David G. Cahill, Wen-Pin Hsieh, Dallas Trinkle, University of Illinois at Urbana-Champaign Bin

  18. Numerical study of the thermoelectric power factor in ultra-thin Si nanowires

    E-Print Network [OSTI]

    1 Numerical study of the thermoelectric power factor in ultra-thin Si nanowires Neophytos Neophytou thermoelectric (TE) performance because of a drastic reduction in their thermal conductivity, l. This has been observed for a variety of materials, even for traditionally poor thermoelectrics such as silicon. Other

  19. Applied Mathematical Sciences, Vol. 4, 2010, no. 11, 505 -514 Efficiency of Inhomogeneous Thermoelectric

    E-Print Network [OSTI]

    Zhou, Hong

    Thermoelectric Generators Hong Zhou Department of Applied Mathematics Naval Postgraduate School, Monterey, CA thermoelectric generators. The effects of different physical parameters on the efficiency of a generator of a thermoelectric generator is insensitive to both the electrical resistivity and thermal conductivity. However

  20. Thermoelectric and Magnetothermoelectric Transport Measurements of Graphene Yuri M. Zuev,1

    E-Print Network [OSTI]

    Kim, Philip

    Thermoelectric and Magnetothermoelectric Transport Measurements of Graphene Yuri M. Zuev,1 Willy, USA (Received 7 December 2008; published 6 March 2009) The conductance and thermoelectric power (TEP of thermal and thermoelectric prop- erties of this two-dimensional material [2­8], only an indirect

  1. Thermoelectrics Combined with Solar Concentration for Electrical and Thermal Cogeneration

    E-Print Network [OSTI]

    Jackson, Philip Robert

    2012-01-01T23:59:59.000Z

    13 2.2.2. Solar Thermal Versus Photovoltaic ..…………..…………doi:10.1038/nmat2090. 17. Solar Thermal Technology on anFigure 2.5: An eSolar solar thermal system in Burbank,

  2. Thermoelectrics Combined with Solar Concentration for Electrical and Thermal Cogeneration

    E-Print Network [OSTI]

    Jackson, Philip Robert

    2012-01-01T23:59:59.000Z

    and Electrical Cogeneration ……………………. …………… 16 2.4.OptimalELECTRICAL AND THERMAL COGENERATION A thesis submitted inFOR ELECTRICAL AND THERMAL COGENERATION A solar tracker and

  3. Gas storage carbon with enhanced thermal conductivity

    DOE Patents [OSTI]

    Burchell, Timothy D. (Oak Ridge, TN); Rogers, Michael Ray (Knoxville, TN); Judkins, Roddie R. (Knoxville, TN)

    2000-01-01T23:59:59.000Z

    A carbon fiber carbon matrix hybrid adsorbent monolith with enhanced thermal conductivity for storing and releasing gas through adsorption and desorption is disclosed. The heat of adsorption of the gas species being adsorbed is sufficiently large to cause hybrid monolith heating during adsorption and hybrid monolith cooling during desorption which significantly reduces the storage capacity of the hybrid monolith, or efficiency and economics of a gas separation process. The extent of this phenomenon depends, to a large extent, on the thermal conductivity of the adsorbent hybrid monolith. This invention is a hybrid version of a carbon fiber monolith, which offers significant enhancements to thermal conductivity and potential for improved gas separation and storage systems.

  4. Glass-like thermal conductivity in high efficiency thermoelectric materials

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels DataDepartment of Energy Your Density Isn't YourTransport(Fact Sheet), Geothermal TechnologiesGeothermal energy toGettingGive Us Your2|

  5. Thermoelectrics Combined with Solar Concentration for Electrical and Thermal Cogeneration

    E-Print Network [OSTI]

    Jackson, Philip Robert

    2012-01-01T23:59:59.000Z

    watts of thermal energy from the sun via the water coolingkilowatt-hours of energy from the sun per square mile perthe heat. The thermal energy from the sun is typically used

  6. Thermoelectrics Combined with Solar Concentration for Electrical and Thermal Cogeneration

    E-Print Network [OSTI]

    Jackson, Philip Robert

    2012-01-01T23:59:59.000Z

    steam turbine or sterling engine connected to an electricalsolar thermal systems, a sterling engine or steam turbine is

  7. Thermal conductivity of bulk and nanowire Mg?SixSn1–x alloys from first principles

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Li, Wu; Lindsay, L.; Broido, D. A.; Stewart, Derek A.; Mingo, Natalio

    2012-11-01T23:59:59.000Z

    The lattice thermal conductivity (?) of the thermoelectric materials, Mg?Si, Mg?Sn, and their alloys, are calculated for bulk and nanowires, without adjustable parameters. We find good agreement with bulk experimental results. For large nanowire diameters, size effects are stronger for the alloy than for the pure compounds. For example, in 200 nm diameter nanowires ? is lower than its bulk value by 30%, 20%, and 20% for Mg?Si?.?Sn?.?, Mg?Si, and Mg?Sn, respectively. For nanowires less than 20 nm thick, the relative decrease surpasses 50%, and it becomes larger in the pure compounds than in the alloy. At room temperature, ? of Mg?SixSn1–x is less sensitive to nanostructuring size effects than SixGe1–x, but more sensitive than PbTexSe1–x. This suggests that further improvement of Mg?SixSn1–x as a nontoxic thermoelectric may be possible.

  8. Thermal conductivity of bulk and nanowire Mg?SixSn1–x alloys from first principles

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Li, Wu; Lindsay, L.; Broido, D. A.; Stewart, Derek A.; Mingo, Natalio

    2012-11-01T23:59:59.000Z

    The lattice thermal conductivity (?) of the thermoelectric materials, Mg?Si, Mg?Sn, and their alloys, are calculated for bulk and nanowires, without adjustable parameters. We find good agreement with bulk experimental results. For large nanowire diameters, size effects are stronger for the alloy than for the pure compounds. For example, in 200 nm diameter nanowires ? is lower than its bulk value by 30%, 20%, and 20% for Mg?Si?.?Sn?.?, Mg?Si, and Mg?Sn, respectively. For nanowires less than 20 nm thick, the relative decrease surpasses 50%, and it becomes larger in the pure compounds than in the alloy. At room temperature, ?more »of Mg?SixSn1–x is less sensitive to nanostructuring size effects than SixGe1–x, but more sensitive than PbTexSe1–x. This suggests that further improvement of Mg?SixSn1–x as a nontoxic thermoelectric may be possible.« less

  9. Thermal Conductivity of Composites Under Di erent Heating Scenarios

    E-Print Network [OSTI]

    : Two dimensional heat transfer model #26;(z), and c p (z) represent the thermal conductivity, density

  10. Gallium ion implantation greatly reduces thermal conductivity and enhances electronic one of ZnO nanowires

    SciTech Connect (OSTI)

    Xia, Minggang, E-mail: xiamg@mail.xjtu.edu.cn [Laboratory of Nanostructure and its Physics Properties, Department of Optical Information Science and Technology, Department of Applied Physics, and MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, School of Science, Xi'an Jiaotong University, 710049 China (China); Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, Singapore 117542 (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Cheng, Zhaofang; Han, Jinyun; Zhang, Shengli [Laboratory of Nanostructure and its Physics Properties, Department of Optical Information Science and Technology, Department of Applied Physics, and MOE Key Laboratory for Non-equilibrium Synthesis and Modulation of Condensed Matter, School of Science, Xi'an Jiaotong University, 710049 China (China); Zheng, Minrui [Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, Singapore 117542 (Singapore); Sow, Chorng-Haur [Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, Singapore 117542 (Singapore); National University of Singapore Nanoscience and Nanotechnology Initiative, National University of Singapore, Singapore 117542 (Singapore); Thong, John T. L. [Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore 117576 (Singapore); Li, Baowen [Department of Physics and Centre for Computational Science and Engineering, National University of Singapore, Singapore 117542 (Singapore); National University of Singapore Nanoscience and Nanotechnology Initiative, National University of Singapore, Singapore 117542 (Singapore); Center for Phononics and Thermal Energy Science, School of Physics Science and Engineering, Tongji University, Shanghai 200092 (China)

    2014-05-15T23:59:59.000Z

    The electrical and thermal conductivities are measured for individual zinc oxide (ZnO) nanowires with and without gallium ion (Ga{sup +}) implantation at room temperature. Our results show that Ga{sup +} implantation enhances electrical conductivity by one order of magnitude from 1.01 × 10{sup 3} ?{sup ?1}m{sup ?1} to 1.46 × 10{sup 4} ?{sup ?1}m{sup ?1} and reduces its thermal conductivity by one order of magnitude from 12.7 Wm{sup ?1}K{sup ?1} to 1.22 Wm{sup ?1}K{sup ?1} for ZnO nanowires of 100 nm in diameter. The measured thermal conductivities are in good agreement with those in theoretical simulation. The increase of electrical conductivity origins in electron donor doping by Ga{sup +} implantation and the decrease of thermal conductivity is due to the longitudinal and transverse acoustic phonons scattering by Ga{sup +} point scattering. For pristine ZnO nanowires, the thermal conductivity decreases only two times when its diameter reduces from 100 nm to 46 nm. Therefore, Ga{sup +}-implantation may be a more effective method than diameter reduction in improving thermoelectric performance.

  11. Conductive Thermal Interaction in Evaporative Cooling Process

    E-Print Network [OSTI]

    Kim, B. S.; Degelman, L. O.

    1990-01-01T23:59:59.000Z

    from the evaporative cooler would often be more than 6.5'F lower than that of a conventional evaporative cooling system due to thermal conduction between water and entering air. - Figure 1 Pad type evaporative cooler. DIRECT EVAPORATIVE COOLER... There are several types of direct evaporative cooler configurations available. Two popular system types are pad type unit and rotary type unit. A number of window mounted units are pad type evaporative coolers (Figure 1). In a pad type cooler, water...

  12. Superconducting thermoelectric generator

    DOE Patents [OSTI]

    Metzger, J.D.; El-Genk, M.S.

    1994-01-01T23:59:59.000Z

    Thermoelectricity is produced by applying a temperature differential to dissimilar electrically conducting or semiconducting materials, thereby producing a voltage that is proportional to the temperature difference. Thermoelectric generators use this effect to directly convert heat into electricity; however, presently-known generators have low efficiencies due to the production of high currents which in turn cause large resistive heating losses. Some thermoelectric generators operate at efficiencies between 4% and 7% in the 800{degrees} to 1200{degrees}C range. According to its major aspects and bradly stated, the present invention is an apparatus and method for producing electricity from heat. In particular, the invention is a thermoelectric generator that juxtaposes a superconducting material and a semiconducting material - so that the superconducting and the semiconducting materials touch - to convert heat energy into electrical energy without resistive losses in the temperature range below the critical temperature of the superconducting material. Preferably, an array of superconducting material is encased in one of several possible configurations within a second material having a high thermal conductivity, preferably a semiconductor, to form a thermoelectric generator.

  13. Experimental studies of the thermoelectric properties of microstructured and nanostructured lead salts

    E-Print Network [OSTI]

    Barron, Kathleen C., 1982-

    2005-01-01T23:59:59.000Z

    Thermoelectric devices allow for direct conversion between thermal and electrical energy. There applications, however, are severely limited by their inefficiency. A reduction in thermal conductivity of a material potentially ...

  14. Approaching the Minimum Thermal Conductivity in Rhenium-Substituted Higher Manganese Silicides

    SciTech Connect (OSTI)

    Chen, Xi [University of Texas at Austin] [University of Texas at Austin; Girard, S. N. [University of Wisconsin, Madison] [University of Wisconsin, Madison; Meng, F. [University of Wisconsin, Madison] [University of Wisconsin, Madison; Lara-Curzio, Edgar [ORNL] [ORNL; Jin, S [University of Wisconsin, Madison] [University of Wisconsin, Madison; Goodenough, J. B. [University of Texas at Austin] [University of Texas at Austin; Zhou, J. S. [University of Texas at Austin] [University of Texas at Austin; Shi, L [University of Texas at Austin] [University of Texas at Austin

    2014-01-01T23:59:59.000Z

    Higher manganese silicides (HMS) made of earth-abundant and non-toxic elements are regarded as promising p-type thermoelectric materials because their complex crystal structure results in low lattice thermal conductivity. It is shown here that the already low thermal conductivity of HMS can be reduced further to approach the minimum thermal conductivity via partial substitu- tion of Mn with heavier rhenium (Re) to increase point defect scattering. The solubility limit of Re in the obtained RexMn1 xSi1.8 is determined to be about x = 0.18. Elemental inhomogeneity and the formation of ReSi1.75 inclusions with 50 200 nm size are found within the HMS matrix. It is found that the power factor does not change markedly at low Re content of x 0.04 before it drops considerably at higher Re contents. Compared to pure HMS, the reduced lattice thermal conductivity in RexMn1 xSi1.8 results in a 25% increase of the peak figure of merit ZT to reach 0.57 0.08 at 800 K for x = 0.04. The suppressed thermal conductivity in the pure RexMn1 xSi1.8 can enable further investigations of the ZT limit of this system by exploring different impurity doping strategies to optimize the carrier concentration and power factor.

  15. An in situ SEM experimental study of the thermal stability of a LAST thermoelectric material

    SciTech Connect (OSTI)

    Ren, Fei [ORNL; Howe, Jane Y [ORNL; Walker, Larry R [ORNL; Case, Eldon D [Michigan State University, East Lansing; Lara-Curzio, Edgar [ORNL

    2011-01-01T23:59:59.000Z

    Thermal stability is a key factor affecting the deployment of thermoelectric (TE) materials in the application of power generation. LAST (Lead-Antimony-Silver-Tellurium) is an emerging material with promising TE properties. The current study focused on the thermal stability of a LAST composition Ag0.86Pb19SbTe20 fabricated from a cast ingot. Using a customized heating stage, the morphology of LAST particles was studied via scanning electron microscopy (SEM) in situ, between room temperature and 575oC. The LAST material included in this study was stable below 550oC. The inclusion phase, which was antimony-rich, has a lower thermal stability than the PbTe-rich matrix. The SEM finding was also consistent with a thermogravimetrtic analysis.

  16. Metallurgy, thermal stability, and failure mode of the commercial Bi-Te-based thermoelectric modules.

    SciTech Connect (OSTI)

    Yang, Nancy Y. C.; Morales, Alfredo Martin

    2009-02-01T23:59:59.000Z

    Bi-Te-based thermoelectric (TE) alloys are excellent candidates for power generation modules. We are interested in reliable TE modules for long-term use at or below 200 C. It is known that the metallurgical characteristics of TE materials and of interconnect components affect the performance of TE modules. Thus, we have conducted an extensive scientific investigation of several commercial TE modules to determine whether they meet our technical requirements. Our main focus is on the metallurgy and thermal stability of (Bi,Sb){sup 2}(Te,Se){sup 3} TE compounds and of other materials used in TE modules in the temperature range between 25 C and 200 C. Our study confirms the material suite used in the construction of TE modules. The module consists of three major components: AlN cover plates; electrical interconnects; and the TE legs, P-doped (Bi{sub 8}Sb{sub 32})(Te{sub 60}) and N-doped (Bi{sub 37}Sb{sub 3})(Te{sub 56}Se{sub 4}). The interconnect assembly contains Sn (Sb {approx} 1wt%) solder, sandwiched between Cu conductor with Ni diffusion barriers on the outside. Potential failure modes of the TE modules in this temperature range were discovered and analyzed. The results show that the metallurgical characteristics of the alloys used in the P and N legs are stable up to 200 C. However, whole TE modules are thermally unstable at temperatures above 160 C, lower than the nominal melting point of the solder suggested by the manufacture. Two failure modes were observed when they were heated above 160 C: solder melting and flowing out of the interconnect assembly; and solder reacting with the TE leg, causing dimensional swelling of the TE legs. The reaction of the solder with the TE leg occurs as the lack of a nickel diffusion barrier on the side of the TE leg where the displaced solder and/or the preexisting solder beads is directly contact the TE material. This study concludes that the present TE modules are not suitable for long-term use at temperatures above 160 C due to the reactivity between the Sn-solder and the (Bi,Sb){sup 2}(Te,Se){sup 3} TE alloys. In order to deploy a reliable TE power generator for use at or below 200 C, alternate interconnect materials must be used and/or a modified module fabrication technique must be developed.

  17. Strain-controlled thermal conductivity in ferroic twinned films

    E-Print Network [OSTI]

    Li, Suzhi

    Large reversible changes of thermal conductivity are induced by mechanical stress, and the corresponding device is a key element for phononics applications. We show that the thermal conductivity ? of ferroic twinned thin ...

  18. Nanostructured thin film thermoelectric composite materials using conductive polymer PEDOT:PSS

    E-Print Network [OSTI]

    Kuryak, Chris A. (Chris Adam)

    2013-01-01T23:59:59.000Z

    Thermoelectric materials have the ability to convert heat directly into electricity. This clean energy technology has advantages over other renewable technologies in that it requires no sunlight, has no moving parts, and ...

  19. Thermal Characterization of Nanostructures and Advanced Engineered Materials

    E-Print Network [OSTI]

    Goyal, Vivek Kumar

    2011-01-01T23:59:59.000Z

    Yan, Y. , Zhang, Q. and Tritt, T.M. , “High ThermoelectricOxford 1963. 3. Tritt, T.M. , “Thermal Conductivity: Theory,

  20. High thermal conductivity aluminum nitride ceramic body

    SciTech Connect (OSTI)

    Huseby, I. C.; Bobik, C. F.

    1985-10-15T23:59:59.000Z

    A process for producing a polycrystalline aluminum nitride ceramic body having a porosity of less than about 10% by volume of said body and a thermal conductivity greater than 1.0 W/cm-K at 22/sup 0/ C., which comprises forming a mixture comprised of aluminum nitride powder and an yttrium additive selected from the group consisting of yttrium, yttrium hydride, yttrium nitride and mixtures thereof, said aluminum nitride and yttrium additive having a predetermined oxygen content, said mixture having a composition wherein the equivalent % of yttrium, aluminum, nitrogen and oxygen shapping said mixture into a compact and sintering said compact at a temperature ranging from about 1850/sup 0/ C. to about 2170/sup 0/ C. in an atmosphere selected from the group consisting of nitrogen, argon, hydrogen and mixtures thereof to produce said polycrystalline body.

  1. Thermoelectric Temperature Control

    E-Print Network [OSTI]

    Saffman, Mark

    NOTE 201TM TECHNICAL Optimizing Thermoelectric Temperature Control Systems #12;2 May 1995 92-040000A © 1995 Wavelength Electronics, Inc. Thermoelectric coolers (TECs) are used in a variety understanding of thermal management techniques and carefully select the thermoelectric module, temperature

  2. Thermoelectrics Partnership: High Performance Thermoelectric...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    High Performance Thermoelectric Waste Heat Recovery System Based on Zintl Phase Materials with Embedded Nanoparticles Thermoelectrics Partnership: High Performance Thermoelectric...

  3. Impact of parasitic thermal effects on thermoelectric property measurements by Harman method

    SciTech Connect (OSTI)

    Kwon, Beomjin, E-mail: bkwon@kist.re.kr; Baek, Seung-Hyub; Keun Kim, Seong; Kim, Jin-Sang, E-mail: jskim@kist.re.kr [Electronic Materials Research Center, Korea Institute of Science and Technology (KIST), Seoul 136-791 (Korea, Republic of)] [Electronic Materials Research Center, Korea Institute of Science and Technology (KIST), Seoul 136-791 (Korea, Republic of)

    2014-04-15T23:59:59.000Z

    Harman method is a rapid and simple technique to measure thermoelectric properties. However, its validity has been often questioned due to the over-simplified assumptions that this method relies on. Here, we quantitatively investigate the influence of the previously ignored parasitic thermal effects on the Harman method and develop a method to determine an intrinsic ZT. We expand the original Harman relation with three extra terms: heat losses via both the lead wires and radiation, and Joule heating within the sample. Based on the expanded Harman relation, we use differential measurement of the sample geometry to measure the intrinsic ZT. To separately evaluate the parasitic terms, the measured ZTs with systematically varied sample geometries and the lead wire types are fitted to the expanded relation. A huge discrepancy (?28%) of the measured ZTs depending on the measurement configuration is observed. We are able to separately evaluate those parasitic terms. This work will help to evaluate the intrinsic thermoelectric property with Harman method by eliminating ambiguities coming from extrinsic effects.

  4. Vehicular Applications of Thermoelectrics

    Broader source: Energy.gov (indexed) [DOE]

    gas. Thermoelectric Element at Toshiba Material Nov. 2007 Shuichi Hase Sango Co. Ltd. Heat-Recovery for ICE Automobiles and Thermal Electric Generation Komatsu Diesel Engine with...

  5. THERMAL CONDUCTIVITY OF HEMP CONCRETES: VARIATION WITH FORMULATION, DENSITY AND

    E-Print Network [OSTI]

    envelope and on the performance of systems. This behaviour is related to hygric and thermal propertiesTHERMAL CONDUCTIVITY OF HEMP CONCRETES: VARIATION WITH FORMULATION, DENSITY AND WATER CONTENT of formulation, density and water content on the thermal conductivity of hemp concretes. The investigations

  6. Thermal conductivity of electroless nickel-phosphorus alloy plating

    SciTech Connect (OSTI)

    Smith, D.D.

    1982-04-01T23:59:59.000Z

    Properties of specific heat, thermal diffusivity, density, and calculated thermal conductivity have been determined for a modified acid bath electroless nickel-12.7 wt% phosphorus alloy between 298 ad 423 K. Thermal conductivity values are about half those of pure nickel.

  7. Thermal Conductivity of Polycrystalline Semiconductors and Ceramics

    E-Print Network [OSTI]

    Wang, Zhaojie

    2012-01-01T23:59:59.000Z

    Brown, C. M. ; Zhang, Q. ; Tritt, T. M. Nano Letters 2010,Monteiro, O. Microelectronics journal Tritt, T. M. , Thermal

  8. Reduced Thermal Conductivity of Compacted Silicon Nanowires

    E-Print Network [OSTI]

    Yuen, Taylor S.

    thermal energy into electrical energy is known as the Seebeck effect, which refers to the generation of an electric

  9. Lattice Thermal conductivity of the Cu3SbSe4-Cu3SbS4 Solid Solution

    SciTech Connect (OSTI)

    Skoug, Eric [Michigan State University, East Lansing; Cain, Jeffrey D. [Michigan State University, East Lansing; Morelli, Donald [Michigan State University, East Lansing; Kirkham, Melanie J [ORNL; Majsztrik, Paul W [ORNL; Lara-Curzio, Edgar [ORNL

    2011-01-01T23:59:59.000Z

    The compositional dependence of the crystal structure and lattice thermal conductivity in the Cu3SbSe4-Cu3SbS4 system has been studied. The lattice parameters of the Cu3SbSe4-xSx compounds decrease linearly with x, and the tetragonal structure (space group no. 121) of the end compounds is maintained at all compositions. The thermal conductivity is much lower than that predicted by a simple rule of mixtures, which is typical for a solid solution. The Debye model produces a very reasonable fit to the experimental lattice thermal conductivity data when phonon scattering due to atomic mass and size differences between Se and S is taken into account. Compounds in this series are likely to improve upon the thermoelectric performance of Cu3SbSe4, which has shown ZT=0.72 when optimized.

  10. Thermal conductivity of graphene nanoribbons in noble gaseous environments

    SciTech Connect (OSTI)

    Zhong, Wei-Rong, E-mail: wrzhong@hotmail.com; Xu, Zhi-Cheng; Zheng, Dong-Qin [Department of Physics and Siyuan Laboratory, College of Science and Engineering, Jinan University, Guangzhou 510632 (China); Ai, Bao-Quan, E-mail: aibq@scnu.edu.cn [Laboratory of Quantum Information Technology, ICMP and SPTE, South China Normal University, Guangzhou 510006 (China)

    2014-02-24T23:59:59.000Z

    We investigate the thermal conductivity of suspended graphene nanoribbons in noble gaseous environments using molecular dynamics simulations. It is reported that the thermal conductivity of perfect graphene nanoribbons decreases with the gaseous pressure. The decreasing is more obvious for the noble gas with large atomic number. However, the gaseous pressure cannot change the thermal conductivity of defective graphene nanoribbons apparently. The phonon spectra of graphene nanoribbons are also provided to give corresponding supports.

  11. Electrical and thermal conductivity of low temperature CVD graphene...

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    and thermal conductivity of low temperature CVD graphene: the effect of disorder This article has been downloaded from IOPscience. Please scroll down to see the full text article....

  12. Microscopic mechanism of low thermal conductivity in lead telluride

    SciTech Connect (OSTI)

    Delaire, Olivier A [ORNL; Ma, Jie [ORNL

    2012-01-01T23:59:59.000Z

    Themicroscopic physics behind low-lattice thermal conductivity of single-crystal rock salt lead telluride (PbTe) is investigated. Mode-dependent phonon (normal and umklapp) scattering rates and their impact on thermal conductivity were quantified by first-principles-based anharmonic lattice dynamics calculations that accurately reproduce thermal conductivity in a wide temperature range. The low thermal conductivity of PbTe is attributed to the scattering of longitudinal acoustic phonons by transverse optical phonons with large anharmonicity and small group velocity of the soft transverse acoustic phonons. This results in enhancing the relative contribution of optical phonons, which are usually minor heat carriers in bulk materials.

  13. The Classical Nature of Thermal Conduction in Nanofluids

    E-Print Network [OSTI]

    Jacob Eapen; Roberto Rusconi; Roberto Piazza; Sidney Yip

    2008-12-31T23:59:59.000Z

    Several new mechanisms have been hypothesized in the recent years to characterize the thermal conduction behavior in nanofluids. In this paper, we show that a large set of nanofluid thermal conductivity data is enveloped by the well-known Hashin and Shtrikman (HS) mean-field bounds for inhomogeneous systems. The thermal conductivity in nanofluids, therefore, is largely dependent on whether the nanoparticles stays dispersed in the base fluid, form linear chain-like configurations, or assume an intermediate configuration. The experimental data, which is strikingly analogous to those in most solid composites and liquid mixtures, provides a strong evidence for the classical nature of thermal conduction in nanofluids.

  14. Thermoelectrics Partnership: Automotive Thermoelectric Modules...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    More Documents & Publications Novel Nanostructured Interface Solution for Automotive Thermoelectric Modules Application Thermoelectrics Partnership: Automotive...

  15. Searching for new thermoelectrics in chemically and structurally complex bismuth chalcogenides

    SciTech Connect (OSTI)

    Chung, D.Y.; Hogan, T.; Schindler, J.; Iordanidis, L.; Brazis, P.; Kannewurf, C.R.; Chen, B.; Uher, C.; Kanatzidis, M.G.

    1997-07-01T23:59:59.000Z

    A solid state chemistry synthetic approach towards identifying new materials with potentially superior thermoelectric properties is presented. Materials with complex compositions and structures also have complex electronic structures which may give rise to high thermoelectric powers and at the same time possess low thermal conductivities. The structures and thermoelectric properties of several new promising compounds with K-Bi-Se, K-Bi-S, Ba-Bi-Te, Cs-Bi-Te, and Rb-bi-Te are reported.

  16. anomalous thermal conductivity: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    conductivity in the range (4.84 ( 0.44) ? 103 to (5.30 ( 0 84 THERMAL CONDUCTIVITY OF HEMP CONCRETES: VARIATION WITH FORMULATION, DENSITY AND Mathematics Websites Summary:...

  17. apparent thermal conductivity: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    conductivity in the range (4.84 ( 0.44) ? 103 to (5.30 ( 0 66 THERMAL CONDUCTIVITY OF HEMP CONCRETES: VARIATION WITH FORMULATION, DENSITY AND Mathematics Websites Summary:...

  18. On the thermal expansion of composite materials and cross-property connection between thermal expansion and thermal conductivity

    E-Print Network [OSTI]

    Sevostianov, Igor

    expansion and thermal conductivity Igor Sevostianov Department of Mechanical and Aerospace Engineering, NewOn the thermal expansion of composite materials and cross-property connection between thermal: Composite material Thermal expansion Cross-property Microstructure Thermal conductivity a b s t r a c

  19. Volume 48 2006 CANADIAN BIOSYSTEMS ENGINEERING 3.1 Thermal conductivity and thermal diffusivity

    E-Print Network [OSTI]

    Saskatchewan, University of

    Volume 48 2006 CANADIAN BIOSYSTEMS ENGINEERING 3.1 Thermal conductivity and thermal diffusivity of timothy hay A. Opoku, L.G. Tabil*, B. Crerar and M.D. Shaw DepartmentofAgriculturaland BioresourceEngineering, L.G., Crerar, B. and Shaw, M.D. 2006. Thermal conductivity and thermal diffusivity of timothy hay

  20. Molecular Level Assessment of Thermal Transport and Thermoelectricity in Materials: From Bulk Alloys to Nanostructures

    E-Print Network [OSTI]

    Kinaci, Alper

    2013-05-02T23:59:59.000Z

    reduction in thermal conductivity is observed at 50% chemical mixture in dot superlattices. The dot radius appears to have little effect on the magnitude of reduction around large concentrations while smaller dots are more influential at dilute systems....

  1. Strain-controlled thermal conductivity in ferroic twinned films

    E-Print Network [OSTI]

    Cambridge, University of

    Alamos National Laboratory, Los Alamos, New Mexico 87545, USA, 3 Department of Materials Science thermoelectric materials5 that display high values of the thermoelectric figure of merit ZT 5 S2 sT/k over broad

  2. THERMAL CONDUCTIVITY AND OTHER PROPERTIES OF CEMENTITIOUS GROUTS

    SciTech Connect (OSTI)

    ALLAN,M.

    1998-05-01T23:59:59.000Z

    The thermal conductivity and other properties cementitious grouts have been investigated in order to determine suitability of these materials for grouting vertical boreholes used with geothermal heat pumps. The roles of mix variables such as water/cement ratio, sand/cement ratio and superplasticizer dosage were measured. In addition to thermal conductivity, the cementitious grouts were also tested for bleeding, permeability, bond to HDPE pipe, shrinkage, coefficient of thermal expansion, exotherm, durability and environmental impact. This paper summarizes the results for selected grout mixes. Relatively high thermal conductivities were obtained and this leads to reduction in predicted bore length and installation costs. Improvements in shrinkage resistance and bonding were achieved.

  3. Superconducting thermoelectric generator

    DOE Patents [OSTI]

    Metzger, J.D.; El-Genk, M.S.

    1998-05-05T23:59:59.000Z

    An apparatus and method for producing electricity from heat is disclosed. The present invention is a thermoelectric generator that uses materials with substantially no electrical resistance, often called superconductors, to efficiently convert heat into electrical energy without resistive losses. Preferably, an array of superconducting elements is encased within a second material with a high thermal conductivity. The second material is preferably a semiconductor. Alternatively, the superconducting material can be doped on a base semiconducting material, or the superconducting material and the semiconducting material can exist as alternating, interleaved layers of waferlike materials. A temperature gradient imposed across the boundary of the two materials establishes an electrical potential related to the magnitude of the temperature gradient. The superconducting material carries the resulting electrical current at zero resistivity, thereby eliminating resistive losses. The elimination of resistive losses significantly increases the conversion efficiency of the thermoelectric device. 4 figs.

  4. Superconducting thermoelectric generator

    DOE Patents [OSTI]

    Metzger, John D. (Eaton's Neck, NY); El-Genk, Mohamed S. (Albuquerque, NM)

    1998-01-01T23:59:59.000Z

    An apparatus and method for producing electricity from heat. The present invention is a thermoelectric generator that uses materials with substantially no electrical resistance, often called superconductors, to efficiently convert heat into electrical energy without resistive losses. Preferably, an array of superconducting elements is encased within a second material with a high thermal conductivity. The second material is preferably a semiconductor. Alternatively, the superconducting material can be doped on a base semiconducting material, or the superconducting material and the semiconducting material can exist as alternating, interleaved layers of waferlike materials. A temperature gradient imposed across the boundary of the two materials establishes an electrical potential related to the magnitude of the temperature gradient. The superconducting material carries the resulting electrical current at zero resistivity, thereby eliminating resistive losses. The elimination of resistive losses significantly increases the conversion efficiency of the thermoelectric device.

  5. Superconducting thermoelectric generator

    DOE Patents [OSTI]

    Metzger, J.D.; El-Genk, M.S.

    1996-01-01T23:59:59.000Z

    An apparatus and method for producing electricity from heat. The present invention is a thermoelectric generator that uses materials with substantially no electrical resistance, often called superconductors, to efficiently convert heat into electrical energy without resistive losses. Preferably, an array of superconducting elements is encased within a second material with a high thermal conductivity. The second material is preferably a semiconductor. Alternatively, the superconducting material can be doped on a base semiconducting material, or the superconducting material and the semiconducting material can exist as alternating, interleaved layers of waferlike materials. A temperature gradient imposed across the boundary of the two materials establishes an electrical potential related to the magnitude of the temperature gradient. The superconducting material carries the resulting electrical current at zero resistivity, thereby eliminating resistive losses. The elimination of resistive losses significantly increases the conversion efficiency of the thermoelectric device.

  6. Correlation Between Structure and Thermoelectric Properties of Bulk High Performance Materials for Energy Conversion

    Broader source: Energy.gov [DOE]

    Rapid solidified precursor converted into crystalline bulks under pressure produced thermoelectric materials of nano-sized grains with strongly coupled grain boundaries, achieving reduced lattice thermal conductivity and increased power factor

  7. Lattice Anharmonicity and Thermal Conductivity from Compressive Sensing of First-Principles Calculations

    SciTech Connect (OSTI)

    Zhou, Fei [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Nielson, Weston [Univ. of California, Los Angeles, CA (United States); Xia, Yi [Univ. of California, Los Angeles, CA (United States); Ozoli?š, Vidvuds [Univ. of California, Los Angeles, CA (United States)

    2014-10-01T23:59:59.000Z

    First-principles prediction of lattice thermal conductivity ?L of strongly anharmonic crystals is a long-standing challenge in solid-state physics. Making use of recent advances in information science, we propose a systematic and rigorous approach to this problem, compressive sensing lattice dynamics. Compressive sensing is used to select the physically important terms in the lattice dynamics model and determine their values in one shot. Nonintuitively, high accuracy is achieved when the model is trained on first-principles forces in quasirandom atomic configurations. The method is demonstrated for Si, NaCl, and Cu12Sb4S13, an earth-abundant thermoelectric with strong phonon-phonon interactions that limit the room-temperature ?L to values near the amorphous limit.

  8. Effect of Aggregation on Thermal Conduction in Colloidal Nanofluids

    SciTech Connect (OSTI)

    R Prasher; W Evans; J Fish; P Meakin; P Phelan; Pawel Keblinski

    2006-08-10T23:59:59.000Z

    Using effective medium theory we demonstrate that the thermal conductivity of nanofluids can be significantly enhanced by the aggregation of nanoparticles into clusters. The enhancement is based purely on conduction and does not require a novel mechanism. Predictions of the effective medium theory are in excellent agreement with detailed numerical calculations on model nanofluids involving fractal clusters and show the importance of cluster morphology on thermal conductivity enhancements.

  9. Analytic DC thermo-electric conductivities in holography with massive gravitons

    E-Print Network [OSTI]

    Andrea Amoretti; Alessandro Braggio; Nicola Maggiore; Nicodemo Magnoli; Daniele Musso

    2014-12-10T23:59:59.000Z

    We provide an analytical derivation of the thermo-electric transport coefficients of the simplest momentum-dissipating model in gauge/gravity where the lack of momentum conservation is realized by means of explicit graviton mass in the bulk. We rely on the procedure recently described by Donos and Gauntlett in the context of Q-lattices and holographic models where momentum dissipation is realized through non-trivial scalars. The analytical approach confirms the results found previously by means of numerical computations.

  10. Design concepts for improved thermoelectric materials

    SciTech Connect (OSTI)

    Slack, G.A.

    1997-07-01T23:59:59.000Z

    Some new guidelines are given that should be useful in the search for thermoelectric materials that are better than those currently available. In particular, clathrate and cryptoclathrate compounds with filler atoms in their cages offer the ability to substantially lower the lattice thermal conductivity.

  11. Thermal conductivity of beryllium-gas packed bed

    SciTech Connect (OSTI)

    Xu, M.; Abdou, M.A.; Raffray, A.R. [Univ. of California, Los Angeles, CA (United States)

    1994-12-31T23:59:59.000Z

    Unsintered packed bed has been suggested as a material form for solid breeder and multiplier in the ITER and fusion power reactor blankets. Study of the effective bed thermal conductivity can provide tools for analysis of the blanket performance under different operating conditions, and of how to actively control the thermal behavior of the blanket. Issues of particular interest are the ability to predict and to control the thermal conductivity. The 2-D model developed at UCLA is used to study the effect of particle diameter, solid-to-gas conductivity ratio, bed porosity, contact area, and surface roughness characteristics on bed thermal conductivity. The study shows that all parameters except bed porosity play important roles in determining the bed thermal controllability.

  12. Mechanisms and models of effective thermal conductivities of nanofluids.

    SciTech Connect (OSTI)

    Yu, W.; France, D. M.; Singh, D.; Timofeeva, E. V.; Smith, D. S.; Routbort, J. L.; Univ. of Illinois

    2010-08-01T23:59:59.000Z

    The physical mechanisms and mathematical models of the effective thermal conductivities of nanofluids have long been of interest to the nanofluid research community because the effective thermal conductivities of nanofluids cannot generally be fully explained and predicted by classical effective medium theories. This review article summarizes considerable progress made on this topic. Specifically, the physical mechanisms and mathematical models of the effective thermal conductivities of nanofluids are reviewed, the potential contributions of those physical mechanisms are evaluated, and the comparisons of the theoretical predictions and experimental data are presented along with opportunities for future research.

  13. Effect of aggregation and interfacial thermal resistance on thermal conductivity of nanocomposites and colloidal nanofluids

    E-Print Network [OSTI]

    Fish, Jacob

    and colloidal nanofluids William Evans a,b , Ravi Prasher c , Jacob Fish b , Paul Meakin d , Patrick Phelan e of aggregation and interfacial thermal resistance on the effective thermal conductivity of nanofluids and nano- composites. We found that the thermal conductivity of nanofluids and nanocomposites can be significantly

  14. In-Pile Thermal Conductivity Measurement Method for Nuclear Fuels

    SciTech Connect (OSTI)

    Joy L. Rempe; Brandon Fox; Heng Ban; Joshua E. Daw; Darrell L. Knudson; Keith G. Condie

    2009-08-01T23:59:59.000Z

    Thermophysical properties of advanced nuclear fuels and materials during irradiation must be known prior to their use in existing, advanced, or next generation reactors. Thermal conductivity is one of the most important properties for predicting fuel and material performance. A joint Utah State University (USU) / Idaho National Laboratory (INL) project, which is being conducted with assistance from the Institute for Energy Technology at the Norway Halden Reactor Project, is investigating in-pile fuel thermal conductivity measurement methods. This paper focuses on one of these methods – a multiple thermocouple method. This two-thermocouple method uses a surrogate fuel rod with Joule heating to simulate volumetric heat generation to gain insights about in-pile detection of thermal conductivity. Preliminary results indicated that this method can measure thermal conductivity over a specific temperature range. This paper reports the thermal conductivity values obtained by this technique and compares these values with thermal property data obtained from standard thermal property measurement techniques available at INL’s High Test Temperature Laboratory. Experimental results and material properties data are also compared to finite element analysis results.

  15. Fabrication and Characterization of a Conduction Cooled Thermal Neutron Filter

    SciTech Connect (OSTI)

    Heather Wampler; Adam Gerth; Heng Ban; Donna Post Guillen; Douglas Porter; Cynthia Papesch

    2010-06-01T23:59:59.000Z

    Installation of a conduction cooled thermal (low-energy) neutron filter in an existing domestic test reactor would provide the U.S. the capability to test new reactor fuels and materials for advanced fast (high-energy) reactor concepts. A composite consisting of Al3Hf-Al has been proposed for the neutron filter due to both the neutron filtering properties of hafnium and the conducting capabilities of aluminum. Knowledge of the thermal conductivity of the Al3Hf-Al composite is essential for the design of the filtering system. The present objectives are to identify a suitable fabrication technique and to measure the thermophysical properties of the Al3Hf intermetallic, which has not been done previous to this study. A centrifugal casting method was used to prepare samples of Al3Hf. X-ray diffraction and Rietveld analysis were conducted to determine the structural make-up of each of the samples. Thermophysical properties were measured as follows: specific heat by a differential scanning calorimeter (DSC), thermal diffusivity by a laser flash thermal diffusivity measuring system, thermal expansion by a dilatometer, and thermal conductivity was calculated based on the previous measurements. All measurements were acquired over a temperature range of 90°C - 375°C with some measurements outside these bounds. The average thermal conductivity of the intermetallic Al3Hf (~7 at.% Hf) was found to be ~ 41 W/m-K for the given temperature range. This information fills a knowledge gap in the thermophysical properties of the intermetallic Al3Hf with the specified percentage of hafnium. A model designed to predict composite properties was used to calculate a thermal conductivity of ~177 W/m-K for an Al3Hf-Al composite with 23 vol% Al3Hf. This calculation was based upon the average thermal conductivity of Al3Hf over the specified temperature range.

  16. Fiber/Matrix Interfacial Thermal Conductance Effect on the Thermal Conductivity of SiC/SiC Composites

    SciTech Connect (OSTI)

    Nguyen, Ba Nghiep; Henager, Charles H.

    2013-04-20T23:59:59.000Z

    SiC/SiC composites used in fusion reactor applications are subjected to high heat fluxes and require knowledge and tailoring of their in-service thermal conductivity. Accurately predicting the thermal conductivity of SiC/SiC composites as a function of temperature will guide the design of these materials for their intended use, which will eventually include the effects of 14-MeV neutron irradiations. This paper applies an Eshelby-Mori-Tanaka approach (EMTA) to compute the thermal conductivity of unirradiated SiC/SiC composites. The homogenization procedure includes three steps. In the first step EMTA computes the homogenized thermal conductivity of the unidirectional (UD) SiC fiber embraced by its coating layer. The second step computes the thermal conductivity of the UD composite formed by the equivalent SiC fibers embedded in a SiC matrix, and finally the thermal conductivity of the as-formed SiC/SiC composite is obtained by averaging the solution for the UD composite over all possible fiber orientations using the second-order fiber orientation tensor. The EMTA predictions for the transverse thermal conductivity of several types of SiC/SiC composites with different fiber types and interfaces are compared to the predicted and experimental results by Youngblood et al.

  17. Odne Stokke Burheim Thermal Signature and Thermal Conductivities of PEM Fuel Cells

    E-Print Network [OSTI]

    Kjelstrup, Signe

    Odne Stokke Burheim Thermal Signature and Thermal Conductivities of PEM Fuel Cells Thesis-Holst for believing in me and for giving me the opportunity to join the work on the "Thermal Effects in Fuel cell The work presented here gives estimates on thermal gradients within the PEM fuel cell, an experimental

  18. Enhanced thermal conductivity through the development of nanofluids

    SciTech Connect (OSTI)

    Eastman, J.A.; Choi, U.S.; Li, S.; Thompson, L.J.; Lee, S.

    1996-11-01T23:59:59.000Z

    Low thermal conductivity is a primary limitation in the development of energy-efficient heat transfer fluids required in many industrial applications. To overcome this limitation, a new class of heat transfer fluids is being developed by suspending nanocrystalline particles in liquids such as water or oil. The resulting nanofluids possess extremely high thermal conductivities compared to the liquids without dispersed nanocrystalline particles. For example, 5 volume % of nanocrystalline copper oxide particles suspended in water results in an improvement in thermal conductivity of almost 60% compared to water without nanoparticles. Excellent suspension properties are also observed, with no significant settling of nanocrystalline oxide particles occurring in stationary fluids over time periods longer than several days. Direct evaporation of Cu nanoparticles into pump oil results in similar improvements in thermal conductivity compared to oxide-in-water systems, but importantly, requires far smaller concentrations of dispersed nanocrystalline powder.

  19. Experimental investigations of solid-solid thermal interface conductance

    E-Print Network [OSTI]

    Collins, Kimberlee C. (Kimberlee Chiyoko)

    2010-01-01T23:59:59.000Z

    Understanding thermal interface conductance is important for nanoscale systems where interfaces can play a critical role in heat transport. In this thesis, pump and probe transient thermoreflectance methods are used to ...

  20. A benchmark study on the thermal conductivity of nanofluids

    E-Print Network [OSTI]

    Buongiorno, Jacopo

    This article reports on the International Nanofluid Property Benchmark Exercise, or INPBE, in which the thermal conductivity of identical samples of colloidally stable dispersions of nanoparticles or “nanofluids,” was ...

  1. Investigation on thermal conductivity and AC impedance of graphite suspension

    E-Print Network [OSTI]

    Wang, Jianjian, S.M. Massachusetts Institute of Technology

    2011-01-01T23:59:59.000Z

    Over the past decade, some groups have reported that nanofluids, which are liquids containing suspensions of nanoparticles, have substantially higher thermal conductivity than that of the base fluids. However, the reported ...

  2. Interplay of point defects, biaxial strain, and thermal conductivity in homoepitaxial SrTiO{sub 3} thin films

    SciTech Connect (OSTI)

    Wiedigen, S.; Kramer, T.; Knorr, I.; Nee, N.; Hoffmann, J.; Volkert, C. A.; Jooss, Ch. [University of Goettingen, Institute of Materials Physics, Friedrich-Hund-Platz 1, 37077 Goettingen (Germany); Feuchter, M.; Kamlah, M. [Karlsruhe Institute of Technology, Institute for Applied Materials, Hermann-von-Helmholtz-Platz 1, 76344 Eggenstein-Leopoldshafen (Germany)

    2012-02-06T23:59:59.000Z

    Separating out effects of point defects and lattice strain on thermal conductivity is essential for improvement of thermoelectric properties of SrTiO{sub 3}. We study relations between defects generated during deposition, induced lattice strain, and their impact on thermal conductivity {kappa} in homoepitaxial SrTiO{sub 3} films prepared by ion-beam sputtering. Lowering the deposition temperature gives rise to lattice expansion by enhancement of point defect density which increases the hardness of the films. Due to a fully coherent substrate-film interface, the lattice misfit induces a large biaxial strain. However, we can show that the temperature dependence of {kappa} is mainly sensitive on the defect concentration.

  3. The thermal conductivity of sediments as a function of porosity

    E-Print Network [OSTI]

    Miller, James W

    1979-01-01T23:59:59.000Z

    1979 Major Subject: Civil Engineering THE THERMAL CONDUCTIVITY OF SEDIMENTS AS A FUNCTION OF POROSITY A Thesis by JAMES WARREN MILLER Approved as to style and content by: Louis J. hompson CE)(Chairman of Committee) Harry M. Coyle (CE)( ember...THE THERMAL CONDUCTIVITY OF SEDIMENTS AS A FUNCTION OF POROSITY A Thesis by JAMES WARREN MILLER Submitted to the Graduate College of Texas AAM University in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE August...

  4. Modeling the thermal conductivity of fiber-reinforced ceramic composites

    SciTech Connect (OSTI)

    Beecher, S.C.; Dinwiddie, R.B.

    1993-06-01T23:59:59.000Z

    A review of models for the prediction of the thermal conductivity of uni-directional fiber-reinforced composites will be presented. The ability of these models to give an accurate prediction of the composite thermal conductivity depends on the amount of information known about the constituent phase properties under the assumption that these properties do not change as a result of processing. Also presented are models that take into account the effects of fiber coatings.

  5. Effective thermal conductivity of packed beds of spheres

    E-Print Network [OSTI]

    Duncan, Allen Buchanan

    1987-01-01T23:59:59.000Z

    EFFECTIVE THERMAL CONDUCTIVITY OF PACKED BEDS OF SPHERES A Thesis ALLEN BUCHANAN DUNCAN Submitted to the Graduate College of Texas ASM University in partial fulfillment of the requirement for the degree ot MASTER OF SCIENCE August 1987... Major Subject: Mechanical Engineering EFFECTIVE THERMAL CONDUCTIVITY OF PACKED BEDS OF SPHERES A Thesis by ALLEN BUCHANAN DUNCAN Approved as to style and content by: G. P. Peterson (Chairman of Committee) G. D. Allen (Member) W. M. Moses...

  6. Thermal contact conductance of a paper handsheet/metal interface

    E-Print Network [OSTI]

    Ng, Kin Hung

    1990-01-01T23:59:59.000Z

    THERMAL CONTACT CONDUCTANCE OF A PAPER HANDSHEET/ METAL INTERFACE A Thesis by KIN HUNG NG Submitted to the Office of Graduate Studies oi Texas ARM University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE... December 1990 Major Subject: Mechanical Engineering THERMAL CONTACT CONDUCTANCE OF A PAPER HANDSHEET/ METAL INTERFACE A Thesis by KIN HUNG NG Approved as to style and content by: J. Seyed- Yagoobi (Chair of Committee) L. S. Fletcher ( Member ) J...

  7. Metallic coatings for enhancement of thermal contact conductance

    SciTech Connect (OSTI)

    Lambert, M.A.; Fletcher, L.S. (Texas A M Univ., College Station, TX (United States))

    1994-04-01T23:59:59.000Z

    The reliability of standard electronic modules may be improved by decreasing overall module temperature. This may be accomplished by enhancing the thermal contact conductance at the interface between the module frame guide rib and the card rail to which the module is clamped. Some metallic coatings, when applied to the card rail, would deform under load, increasing the contact area and associated conductance. This investigation evaluates the enhancements in thermal conductance afforded by vapor deposited silver and gold coatings. Experimental thermal conductance measurements were made for anodized aluminum 6101-T6 and electroless nickel-plated copper C11000-H03 card materials to the aluminum A356-T61 rail material. Conductance values for the electroless nickel-plated copper junction ranged from 600 to 2800 W/m(exp 2)K and those for the anodized aluminum junction ranged from 25 to 91 W/m(exp 2)K for contact pressures of 0.172-0.862 MPa and mean junction temperatures of 20-100 C. Experimental thermal conductance values of vapor deposited silver- and gold-coated aluminum A356-T61 rail surfaces indicate thermal enhancements of 1.25-2.19 for the electroless nickel-plated copper junctions and 1.79-3.41 for the anodized aluminum junctions. The silver and gold coatings provide significant thermal enhancement; however, these coating-substrate combinations are susceptible to galvanic corrosion under some conditions. 25 refs.

  8. THERMAL CONDUCTIVITY OF NON-REPOSITORY LITHOSTRATIGRAPHIC LAYERS

    SciTech Connect (OSTI)

    R. JONES

    2004-10-22T23:59:59.000Z

    This model report addresses activities described in ''Technical Work Plan for: Near-Field Environment and Transport Thermal Properties and Analysis Reports Integration'' (BSC 2004 [DIRS 171708]). The model develops values for thermal conductivity, and its uncertainty, for the nonrepository layers of Yucca Mountain; in addition, the model provides estimates for matrix porosity and dry bulk density for the nonrepository layers. The studied lithostratigraphic units, as identified in the ''Geologic Framework Model'' (GFM 2000) (BSC 2004 [DIRS 170029]), are the Timber Mountain Group, the Tiva Canyon Tuff, the Yucca Mountain Tuff, the Pah Canyon Tuff, the Topopah Spring Tuff (excluding the repository layers), the Calico Hills Formation, the Prow Pass Tuff, the Bullfrog Tuff, and the Tram Tuff. The deepest model units of the GFM (Tund and Paleozoic) are excluded from this study because no data suitable for model input are available. The parameter estimates developed in this report are used as input to various models and calculations that simulate heat transport through the rock mass. Specifically, analysis model reports that use product output from this report are: (1) Drift-scale coupled processes (DST and TH seepage) models; (2) Drift degradation analysis; (3) Multiscale thermohydrologic model; and (4) Ventilation model and analysis report. In keeping with the methodology of the thermal conductivity model for the repository layers in ''Thermal Conductivity of the Potential Repository Horizon'' (BSC 2004 [DIRS 169854]), the Hsu et al. (1995 [DIRS 158073]) three-dimensional (3-D) cubic model (referred to herein as ''the Hsu model'') was used to represent the matrix thermal conductivity as a function of the four parameters (matrix porosity, thermal conductivity of the saturating fluid, thermal conductivity of the solid, and geometric connectivity of the solid). The Hsu model requires input data from each test specimen to meet three specific conditions: (1) Known value for matrix porosity; (2) Known values for wet and dry thermal conductivity; and (3) The location of the measured specimen in relation to the model stratigraphic unit. The only matrix thermal conductivity values developed are limited to fully saturated and dry conditions. The model does not include the effects of convection and thermal radiation in voids. The model does not include temperature dependence of thermal conductivity, porosity, or bulk density.

  9. Electron thermal conductivity owing to collisions between degenerate electrons

    E-Print Network [OSTI]

    P. S. Shternin; D. G. Yakovlev

    2006-08-17T23:59:59.000Z

    We calculate the thermal conductivity of electrons produced by electron-electron Coulomb scattering in a strongly degenerate electron gas taking into account the Landau damping of transverse plasmons. The Landau damping strongly reduces this conductivity in the domain of ultrarelativistic electrons at temperatures below the electron plasma temperature. In the inner crust of a neutron star at temperatures T scattering and becomes competitive with the the electron conductivity due to scattering of electrons by impurity ions.

  10. Holey Silicon as an Efficient Thermoelectric Material

    SciTech Connect (OSTI)

    Tang, Jinyao; Wang, Hung-Ta; Hyun Lee, Dong; Fardy, Melissa; Huo, Ziyang; Russell, Thomas P.; Yang, Peidong

    2010-09-30T23:59:59.000Z

    This work investigated the thermoelectric properties of thin silicon membranes that have been decorated with high density of nanoscopic holes. These ?holey silicon? (HS) structures were fabricated by either nanosphere or block-copolymer lithography, both of which are scalable for practical device application. By reducing the pitch of the hexagonal holey pattern down to 55 nm with 35percent porosity, the thermal conductivity of HS is consistently reduced by 2 orders of magnitude and approaches the amorphous limit. With a ZT value of 0.4 at room temperature, the thermoelectric performance of HS is comparable with the best value recorded in silicon nanowire system.

  11. Enhanced thermoelectric properties in hybrid graphene-boron nitride nanoribbons

    E-Print Network [OSTI]

    Kaike Yang; Yuanping Chen; Roberto D'Agosta; Yuee Xie; Jianxin Zhong; Angel Rubio

    2012-04-06T23:59:59.000Z

    The thermoelectric properties of hybrid graphene-boron nitride nanoribbons (BCNNRs) are investigated using the non-equilibrium Green's function (NEGF) approach. We find that the thermoelectric figure of merit (ZT) can be remarkably enhanced by periodically embedding hexagonal BN (h-BN) into graphene nanoribbons (GNRs). Compared to pristine GNRs, the ZT for armchair-edged BCNNRs with width index 3p+2 is enhanced up to 10~20 times while the ZT of nanoribbons with other widths is enhanced just by 1.5~3 times. As for zigzag-edge nanoribbons, the ZT is enhanced up to 2~3 times. This improvement comes from the combined increase in the Seebeck coefficient and the reduction in the thermal conductivity outweighing the decrease in the electrical conductance. In addition, the effect of component ratio of h-BN on the thermoelectric transport properties is discussed. These results qualify BCNNRs as a promising candidate for building outstanding thermoelectric devices.

  12. Enhanced thermoelectric properties in hybrid graphene-boron nitride nanoribbons

    E-Print Network [OSTI]

    Yang, Kaike; D'Agosta, Roberto; Xie, Yuee; Zhong, Jianxin; Rubio, Angel

    2012-01-01T23:59:59.000Z

    The thermoelectric properties of hybrid graphene-boron nitride nanoribbons (BCNNRs) are investigated using the non-equilibrium Green's function (NEGF) approach. We find that the thermoelectric figure of merit (ZT) can be remarkably enhanced by periodically embedding hexagonal BN (h-BN) into graphene nanoribbons (GNRs). Compared to pristine GNRs, the ZT for armchair-edged BCNNRs with width index 3p+2 is enhanced up to 10~20 times while the ZT of nanoribbons with other widths is enhanced just by 1.5~3 times. As for zigzag-edge nanoribbons, the ZT is enhanced up to 2~3 times. This improvement comes from the combined increase in the Seebeck coefficient and the reduction in the thermal conductivity outweighing the decrease in the electrical conductance. In addition, the effect of component ratio of h-BN on the thermoelectric transport properties is discussed. These results qualify BCNNRs as a promising candidate for building outstanding thermoelectric devices.

  13. Thermoelectric materials development. Final report

    SciTech Connect (OSTI)

    Fleurial, J.P.; Caillat, T.; Borshchevsky, A.

    1998-09-01T23:59:59.000Z

    A systematic search for advanced thermoelectric materials was initiated at JPL several years ago to evaluate candidate materials which includes consideration of the following property attributes: (1) semiconducting properties; (2) large Seebeck coefficient; (3) high carrier mobility and high electrical conductivity; (4) low lattice thermal conductivity; and (5) chemical stability and low vapor pressure. Through this candidate screening process, JPL identified several families of materials as promising candidates for improved thermoelectric materials including the skutterudite family. There are several programs supporting various phases of the effort on these materials. As part of an ongoing effort to develop skutterudite materials with lower thermal conductivity values, several solid solutions and filled skutterudite materials were investigated under the effort sponsored by DOE. The efforts have primarily focused on: (1) study of existence and properties of solid solutions between the binary compounds CoSb{sub 3} and IrSb{sub 3}, and RuSb{sub 2}Te, and (2) CeFe{sub 4{minus}x}Sb{sub 12} based filled compositions. For the solid solutions, the lattice thermal conductivity reduction was expected to be reduced by the introduction of the Te and Ru atoms while in the case of CeFe{sub 4{minus}x}Ru{sub x}Sb{sub 12} based filled compositions. For the solid solutions, the lattice thermal conductivity reduction was expected to be reduced by the introduction of the Te and Ru atoms while in the case of CeFe{sub 4{minus}x}Ru{sub x}Sb{sub 12} filled compositions, the reduction would be caused by the rattling of Ce atoms located in the empty voids of the skutterudite structure and the substitution of Fe for Ru. The details of the sample preparation and characterization of their thermoelectric properties are reported in this report.

  14. Lattice thermal conductivity of nanograined half-Heusler solid solutions

    SciTech Connect (OSTI)

    Geng, Huiyuan, E-mail: genghuiyuan@hit.edu.cn; Meng, Xianfu; Zhang, Hao; Zhang, Jian [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China)

    2014-05-19T23:59:59.000Z

    We report a phenomenological model of atomic weight, lattice constant, temperature, and grain size to calculate the high-temperature lattice thermal conductivity of nanograined solid solutions. The theoretical treatment developed here is reasonably consistent with the experimental results of n-type MNiSn and p-type MCoSb alloys, where M is the combination of Hf, Zr, and Ti. For disordered half-Heusler alloys with moderated grain sizes, we predict that the reduction in lattice thermal conductivity due to grain boundary scattering is independent of the scattering parameter, which characterizes the phonon scattering cross section of point defects. In addition, the lattice thermal conductivity falls off with temperature as T{sup –1?2} around the Debye temperature.

  15. Thermally conductive cementitious grout for geothermal heat pump systems

    DOE Patents [OSTI]

    Allan, Marita (Old Field, NY)

    2001-01-01T23:59:59.000Z

    A thermally conductive cement-sand grout for use with a geothermal heat pump system. The cement sand grout contains cement, silica sand, a superplasticizer, water and optionally bentonite. The present invention also includes a method of filling boreholes used for geothermal heat pump systems with the thermally conductive cement-sand grout. The cement-sand grout has improved thermal conductivity over neat cement and bentonite grouts, which allows shallower bore holes to be used to provide an equivalent heat transfer capacity. In addition, the cement-sand grouts of the present invention also provide improved bond strengths and decreased permeabilities. The cement-sand grouts can also contain blast furnace slag, fly ash, a thermoplastic air entraining agent, latex, a shrinkage reducing admixture, calcium oxide and combinations thereof.

  16. Microsegregation effects on the thermal conductivity of silicon-germanium alloys

    SciTech Connect (OSTI)

    Lee, Yongjin; Hwang, Gyeong S., E-mail: gshwang@che.utexas.edu [Department of Chemical Engineering, University of Texas, Austin, Texas 78712 (United States)

    2013-11-07T23:59:59.000Z

    A silicon-germanium (SiGe) alloy is a promising candidate for thermoelectric materials; while it shows a significantly reduced thermal conductivity (?) as compared to pure Si and Ge, the ? values obtained from previous experiments and computations tend to be widely scattered. We present here a computational analysis of thermal transport in SiGe, particularly the effects of the local segregation (microsegregation) of alloying elements. Our nonequilibrium molecular dynamics simulations confirm the strong dependence of ? on the Si:Ge ratio and the occurrence of the minimum ? around Si{sub 0.8}Ge{sub 0.2}, consistent with existing experimental observations. Moreover, our study clearly demonstrates that the ? of Si{sub 0.8}Ge{sub 0.2} increases substantially and monotonically as Ge atoms undergo segregation; that is, the magnitude of alloy scattering is found to be sensitive to homogeneity in the distribution of alloying elements. Nonequilibrium Green's function analysis also shows that such microsegregation enhances phonon transmission due to the reduced number of scattering centers. The findings highlight that distribution homogeneity, along with composition, can be a critical factor in determining the ? of SiGe alloys.

  17. High thermal conductivity lossy dielectric using a multi layer configuration

    DOE Patents [OSTI]

    Tiegs, Terry N. (Lenoir City, TN); Kiggans, Jr., James O. (Oak Ridge, TN)

    2003-01-01T23:59:59.000Z

    Systems and methods are described for loss dielectrics. A loss dielectric includes at least one high dielectric loss layer and at least one high thermal conductivity-electrically insulating layer adjacent the at least one high dielectric loss layer. A method of manufacturing a loss dielectric includes providing at least one high dielectric loss layer and providing at least one high thermal conductivity-electrically insulating layer adjacent the at least one high dielectric loss layer. The systems and methods provide advantages because the loss dielectrics are less costly and more environmentally friendly than the available alternatives.

  18. Developing a High Thermal Conductivity Fuel with Silicon Carbide Additives

    SciTech Connect (OSTI)

    baney, Ronald; Tulenko, James

    2012-11-20T23:59:59.000Z

    The objective of this research is to increase the thermal conductivity of uranium oxide (UO{sub 2}) without significantly impacting its neutronic properties. The concept is to incorporate another high thermal conductivity material, silicon carbide (SiC), in the form of whiskers or from nanoparticles of SiC and a SiC polymeric precursor into UO{sub 2}. This is expected to form a percolation pathway lattice for conductive heat transfer out of the fuel pellet. The thermal conductivity of SiC would control the overall fuel pellet thermal conductivity. The challenge is to show the effectiveness of a low temperature sintering process, because of a UO{sub 2}-SiC reaction at 1,377°C, a temperature far below the normal sintering temperature. Researchers will study three strategies to overcome the processing difficulties associated with pore clogging and the chemical reaction of SiC and UO{sub 2} at temperatures above 1,300°C:

  19. Solar Thermoelectric Energy Conversion

    Broader source: Energy.gov (indexed) [DOE]

    SOLID-STATE SOLAR-THERMAL ENERGY CONVERSION CENTER NanoEngineering Group Solar Thermoelectric Energy Conversion Gang Chen, 1 Daniel Kraemer, 1 Bed Poudel, 2 Hsien-Ping Feng, 1 J....

  20. Solar Thermoelectrics Mercouri Kanatzidis,

    E-Print Network [OSTI]

    Kanatzidis, Mercouri G

    Solar Thermoelectrics Mercouri Kanatzidis, Materials Science Division December 15, 2009 #12;2 Heat #12;13 What is the dot made of? Cook, Kramer #12;14 Nanostructures reduce the lattice thermal

  1. Pretest Caluculations of Temperature Changes for Field Thermal Conductivity Tests

    SciTech Connect (OSTI)

    N.S. Brodsky

    2002-07-17T23:59:59.000Z

    A large volume fraction of the potential monitored geologic repository at Yucca Mountain may reside in the Tptpll (Tertiary, Paintbrush Group, Topopah Spring Tuff, crystal poor, lower lithophysal) lithostratigraphic unit. This unit is characterized by voids, or lithophysae, which range in size from centimeters to meters. A series of thermal conductivity field tests are planned in the Enhanced Characterization of the Repository Block (ECRB) Cross Drift. The objective of the pretest calculation described in this document is to predict changes in temperatures in the surrounding rock for these tests for a given heater power and a set of thermal transport properties. The calculation can be extended, as described in this document, to obtain thermal conductivity, thermal capacitance (density x heat capacity, J {center_dot} m{sup -3} {center_dot} K{sup -1}), and thermal diffusivity from the field data. The work has been conducted under the ''Technical Work Plan For: Testing and Monitoring'' (BSC 2001). One of the outcomes of this analysis is to determine the initial output of the heater. This heater output must be sufficiently high that it will provide results in a reasonably short period of time (within several weeks or a month) and be sufficiently high that the heat increase is detectable by the instruments employed in the test. The test will be conducted in stages and heater output will be step increased as the test progresses. If the initial temperature is set too high, the experiment will not have as many steps and thus fewer thermal conductivity data points will result.

  2. Thermoelectric Generators 1. Thermoelectric generator

    E-Print Network [OSTI]

    Lee, Ho Sung

    1 Thermoelectric Generators HoSung Lee 1. Thermoelectric generator 1.1 Basic Equations In 1821 effects are called the thermoelectric effects. The mechanisms of thermoelectricity were not understood. Cold Hot I - -- - - - - -- Figure 1 Electron concentration in a thermoelectric material. #12;2 A large

  3. Thermal conductivity of silicene from first-principles

    SciTech Connect (OSTI)

    Xie, Han; Bao, Hua, E-mail: hum@ghi.rwth-aachen.de, E-mail: hua.bao@sjtu.edu.cn [University of Michigan–Shanghai Jiao Tong University Joint Institute, Shanghai Jiao Tong University, Shanghai 200240 (China); Hu, Ming, E-mail: hum@ghi.rwth-aachen.de, E-mail: hua.bao@sjtu.edu.cn [Institute of Mineral Engineering, Division of Materials Science and Engineering, Faculty of Georesources and Materials Engineering, RWTH Aachen University, Aachen 52064 (Germany); Aachen Institute for Advanced Study in Computational Engineering Science (AICES), RWTH Aachen University, Aachen 52062 (Germany)

    2014-03-31T23:59:59.000Z

    Silicene, as a graphene-like two-dimensional material, now receives exceptional attention of a wide community of scientists and engineers beyond graphene. Despite extensive study on its electric property, little research has been done to accurately calculate the phonon transport of silicene so far. In this paper, thermal conductivity of monolayer silicene is predicted from first-principles method. At 300?K, the thermal conductivity of monolayer silicene is found to be 9.4?W/mK and much smaller than bulk silicon. The contributions from in-plane and out-of-plane vibrations to thermal conductivity are quantified, and the out-of-plane vibration contributes less than 10% of the overall thermal conductivity, which is different from the results of the similar studies on graphene. The difference is explained by the presence of small buckling, which breaks the reflectional symmetry of the structure. The flexural modes are thus not purely out-of-plane vibration and have strong scattering with other modes.

  4. Mode dependent lattice thermal conductivity of single layer graphene

    SciTech Connect (OSTI)

    Wei, Zhiyong; Yang, Juekuan; Bi, Kedong; Chen, Yunfei, E-mail: yunfeichen@seu.edu.cn [Jiangsu Key Laboratory for Design and Manufacture of Micro/Nano Biomedical Instruments and School of Mechanical Engineering, Southeast University, Nanjing 210096 (China)

    2014-10-21T23:59:59.000Z

    Molecular dynamics simulation is performed to extract the phonon dispersion and phonon lifetime of single layer graphene. The mode dependent thermal conductivity is calculated from the phonon kinetic theory. The predicted thermal conductivity at room temperature exhibits important quantum effects due to the high Debye temperature of graphene. But the quantum effects are reduced significantly when the simulated temperature is as high as 1000 K. Our calculations show that out-of-plane modes contribute about 41.1% to the total thermal conductivity at room temperature. The relative contribution of out-of-plane modes has a little decrease with the increase of temperature. Contact with substrate can reduce both the total thermal conductivity of graphene and the relative contribution of out-of-plane modes, in agreement with previous experiments and theories. Increasing the coupling strength between graphene and substrate can further reduce the relative contribution of out-of-plane modes. The present investigations also show that the relative contribution of different mode phonons is not sensitive to the grain size of graphene. The obtained phonon relaxation time provides useful insight for understanding the phonon mean free path and the size effects in graphene.

  5. Superior Thermal Conductivity of Single-Layer Graphene

    E-Print Network [OSTI]

    Superior Thermal Conductivity of Single-Layer Graphene Alexander A. Balandin,*,, Suchismita Ghosh, Department of Electrical Engineering, UniVersity of California-RiVerside, RiVerside, California 92521, Materials Science and Engineering Program, Bourns College of Engineering, UniVersity of California

  6. Anomalous Size Dependence of the Thermal Conductivity of Graphene Ribbons

    E-Print Network [OSTI]

    Anomalous Size Dependence of the Thermal Conductivity of Graphene Ribbons Denis L. Nika,, Artur S. Askerov, and Alexander A. Balandin*, Nano-Device Laboratory, Department of Electrical Engineering and Materials Science and Engineering Program, Bourns College of Engineering, University of California

  7. The Thermal Conductivity of Low Density Concretes Containing Perlite

    E-Print Network [OSTI]

    Yarbrough, D. W.

    concretes made from Portland cement and perlite has been measured near room temperature using an unguarded linear heat flow apparatus. Perlite based concretes having densities from 44.3 1b/ft 3 to 66.6 1b/ft 3 were found to have thermal conductivities...

  8. Analysis of measurements of the thermal conductivity of liquid urania

    SciTech Connect (OSTI)

    Fink, J.K.; Leibowitz, L.

    1984-09-17T23:59:59.000Z

    An analysis was performed of the three existing measurements of the thermal conductivity and thermal diffusivity of molten uranium dioxide. A transient heat transfer code (THTB) was used for this analysis. A much smaller range of values for thermal conductivity than originally reported was found: the original values ranged from 2.4 to 11 W . m/sup -1/ . K/sup -1/, with a mean of 7.3 W . m/sup -1/ . K/sup -1/, whereas the recalculated values ranged from 4.5 to 6.75 W . m/sup -1/ . K/sup -1/, with a mean of 5.6 W . m/sup -1/ . K/sup -1/.

  9. The thermal expansion coefficient as a key design parameter for thermoelectric materials and its relationship to processing-dependent bloating

    SciTech Connect (OSTI)

    Ni, Jennifer E. [Michigan State University, East Lansing; Case, Eldon D [Michigan State University, East Lansing; Schmidt, Robert [Michigan State University, East Lansing; Wu, Chun-I [Michigan State University, East Lansing; Hogan, Timothy [Michigan State University, East Lansing; Trejo, Rosa M [ORNL; Kirkham, Melanie J [ORNL; Lara-Curzio, Edgar [ORNL; Kanatzidis, Mercouri G. [Northwestern University, Evanston

    2013-01-01T23:59:59.000Z

    The coefficient of thermal expansion (CTE) is a key design parameter for thermoelectric (TE) materials, especially in energy harvesting applications since stresses generated by CTE mismatch, thermal gradients, and thermal transients scale with the CTE of the TE material. For the PbTe PbS-based TE material (Pb 0.95 Sn 0.05 Te) 0.92(PbS) 0.08 0.055 % PbI 2 over the temperature ranges of 293 543 and 293 773 K, a CTE, alpha avg , of 21.4 0.3 x 10-6 K-1 was measured using (1) dilatometry and (2) high-temperature X-ray diffraction (HT-XRD) for powder and bulk specimens. The CTE values measured via dilatometry and HT-XRD are similar to the literature values for other Pb-based chalcogenides. However, the processing technique was found to impact the thermal expansion such that bloating (which leads to a hysteresis in thermal expansion) occurred for hot pressed billets heated to temperatures [603 K while specimens fabricated by pulsed electric current sintering and as-cast specimens did not show a bloating-modified thermal expansion even for temperatures up to 663 K. The relationship of bloating to the processing techniques is discussed, along with a pos- sible mechanism for inhibiting bloating in powder processed specimens.

  10. Thermal Crosslinking of Organic Semiconducting Polythiophene Improves Transverse Hole Conductivity

    SciTech Connect (OSTI)

    Gearba, I.R.; Nam, C.-Y.; Pindak, R.; Black, C.T.

    2009-10-26T23:59:59.000Z

    Thermal crosslinking using a suitable radical initiator simultaneously improves electrical conductivity in the semiconducting polymer poly(3-hexylthiophene) and makes the material insoluble. Crosslinked polythiophene shows as much as a fivefold increase in hole conductivity across the film thickness without any shift in spectral light absorption. Grazing incidence x-ray diffraction reveals more in-plane polymer lamellae stacking with only a small decrease in film crystallinity. Improved transverse conductivity increases the performance of model planar solar cells by threefold, from 0.07% to 0.2%. The ability to render polythiophene insoluble without disrupting film structural order enables fabrication pathways to more complex device architectures.

  11. Heat conduction through a trapped solid: effect of structural changes on thermal conductance

    E-Print Network [OSTI]

    Debasish Chaudhuri; Abhishek Chaudhuri; Surajit Sengupta

    2007-03-20T23:59:59.000Z

    We study the conduction of heat across a narrow solid strip trapped by an external potential and in contact with its own liquid. Structural changes, consisting of addition and deletion of crystal layers in the trapped solid, are produced by altering the depth of the confining potential. Nonequilibrium molecular dynamics simulations and, wherever possible, simple analytical calculations are used to obtain the thermal resistance in the liquid, solid and interfacial regions (Kapitza or contact resistance). We show that these layering transitions are accompanied by sharp jumps in the contact thermal resistance. Dislocations, if present, are shown to increase the thermal resistance of the strip drastically.

  12. Green thermoelectrics: Observation and analysis of plant thermoelectric response

    E-Print Network [OSTI]

    Goupil, C; Khamsing, A; Apertet, Y; Bouteau, F; Mancuso, S; Patino, R; Lecoeur, Ph

    2015-01-01T23:59:59.000Z

    Plants are sensitive to thermal and electrical effects; yet the coupling of both, known as thermoelectricity, and its quantitative measurement in vegetal systems never were reported. We recorded the thermoelectric response of bean sprouts under various thermal conditions and stress. The obtained experimental data unambiguously demonstrate that a temperature difference between the roots and the leaves of a bean sprout induces a thermoelectric voltage between these two points. Basing our analysis of the data on the force-flux formalism of linear response theory, we found that the strength of the vegetal equivalent to the thermoelectric coupling is one order of magnitude larger than that in the best thermoelectric materials. Experimental data also show the importance of the thermal stress variation rate in the plant's electrophysiological response. Therefore, thermoelectric effects are sufficiently important to partake in the complex and intertwined processes of energy and matter transport within plants.

  13. Effect of interfacial interactions on the thermal conductivity and interfacial thermal conductance in tungsten–graphene layered structure

    SciTech Connect (OSTI)

    Jagannadham, K., E-mail: jag-kasichainula@ncsu.edu [Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2014-09-01T23:59:59.000Z

    Graphene film was deposited by microwave plasma assisted deposition on polished oxygen free high conductivity copper foils. Tungsten–graphene layered film was formed by deposition of tungsten film by magnetron sputtering on the graphene covered copper foils. Tungsten film was also deposited directly on copper foil without graphene as the intermediate film. The tungsten–graphene–copper samples were heated at different temperatures up to 900?°C in argon atmosphere to form an interfacial tungsten carbide film. Tungsten film deposited on thicker graphene platelets dispersed on silicon wafer was also heated at 900?°C to identify the formation of tungsten carbide film by reaction of tungsten with graphene platelets. The films were characterized by scanning electron microscopy, Raman spectroscopy, and x-ray diffraction. It was found that tungsten carbide film formed at the interface upon heating only above 650?°C. Transient thermoreflectance signal from the tungsten film surface on the samples was collected and modeled using one-dimensional heat equation. The experimental and modeled results showed that the presence of graphene at the interface reduced the cross-plane effective thermal conductivity and the interfacial thermal conductance of the layer structure. Heating at 650 and 900?°C in argon further reduced the cross-plane thermal conductivity and interface thermal conductance as a result of formation nanocrystalline tungsten carbide at the interface leading to separation and formation of voids. The present results emphasize that interfacial interactions between graphene and carbide forming bcc and hcp elements will reduce the cross-plane effective thermal conductivity in composites.

  14. Determination of Thermal Diffusivities, Thermal Conductivities, and Sound Speeds of Room-Temperature Ionic Liquids by the Transient Grating Technique

    E-Print Network [OSTI]

    Reid, Scott A.

    Determination of Thermal Diffusivities, Thermal Conductivities, and Sound Speeds of Room. The experiments give thermal diffusivities from which thermal conductivities can be determined, sound speeds not only on the sound speed but also on the thermal diffusivity and acoustic damping of the RTILs

  15. VALIDATION OF A THERMAL CONDUCTIVITY MEASUREMENT SYSTEM FOR FUEL COMPACTS

    SciTech Connect (OSTI)

    Jeff Phillips; Colby Jensen; Changhu Xing; Heng Ban

    2011-03-01T23:59:59.000Z

    A high temperature guarded-comparative-longitudinal heat flow measurement system has been built to measure the thermal conductivity of a composite nuclear fuel compact. It is a steady-state measurement device designed to operate over a temperature range of 300 K to 1200 K. No existing apparatus is currently available for obtaining the thermal conductivity of the composite fuel in a non-destructive manner due to the compact’s unique geometry and composite nature. The current system design has been adapted from ASTM E 1225. As a way to simplify the design and operation of the system, it uses a unique radiative heat sink to conduct heat away from the sample column. A finite element analysis was performed on the measurement system to analyze the associated error for various operating conditions. Optimal operational conditions have been discovered through this analysis and results are presented. Several materials have been measured by the system and results are presented for stainless steel 304, inconel 625, and 99.95% pure iron covering a range of thermal conductivities of 10 W/m*K to 70 W/m*K. A comparison of the results has been made to data from existing literature.

  16. Interfacial thermal conductance in spun-cast polymer films and polymer brushes

    E-Print Network [OSTI]

    Braun, Paul

    Interfacial thermal conductance in spun-cast polymer films and polymer brushes Mark D. Losego inorganic materials and anharmonic polymers have potentially intriguing thermal transport behavior. The low thermal conductivity of amorphous polymers limits significant interfacial effects to polymer film

  17. Thermoelectrics Partnership: Automotive Thermoelectric Modules...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    ace067goodson2011o.pdf More Documents & Publications Thermoelectrics Partnership: Automotive Thermoelectric Modules with Scalable Thermo- and Electro-Mechanical Interfaces Novel...

  18. Lattice thermal conductivity of filled skutterudites: An anharmonicity perspective

    SciTech Connect (OSTI)

    Geng, Huiyuan, E-mail: genghuiyuan@hit.edu.cn; Meng, Xianfu; Zhang, Hao; Zhang, Jian [State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001 (China)

    2014-10-28T23:59:59.000Z

    We report a phenomenological model to calculate the high-temperature lattice thermal conductivity of filled skutterudite antimonides. The model needs no phonon resonant scattering terms. Instead, we assume that umklapp processes dominate the high-temperature phonon scattering. In order to represent the anharmonicity introduced by the filling atom, we introduce a Gaussian term into the relaxation time of the umklapp process. The developed model agrees remarkably well with the experimental results of RE{sub f}Co{sub 4}Sb{sub 12} and RE{sub f}Fe{sub 4}Sb{sub 12} (RE?=?Yb, Ba, and Ca) alloys. To further test the validity of our model, we calculate the lattice thermal conductivity of nanostructured or multi-filled skutterudites. The calculation results are also in good agreement with experiment, increasing our confidence in the developed anharmonicity model.

  19. Thermal Conductivity of the Potential Repository Horizon Model Report

    SciTech Connect (OSTI)

    J. Ramsey

    2002-08-29T23:59:59.000Z

    The purpose of this report is to assess the spatial variability and uncertainty of thermal conductivity in the host horizon for the proposed repository at Yucca Mountain. More specifically, the lithostratigraphic units studied are located within the Topopah Spring Tuff (Tpt) and consist of the upper lithophysal zone (Tptpul), the middle nonlithophysal zone (Tptpmn), the lower lithophysal zone (Tptpll), and the lower nonlithophysal zone (Tptpln). The Tptpul is the layer directly above the repository host layers, which consist of the Tptpmn, Tptpll, and the Tptpln. Current design plans indicate that the largest portion of the repository will be excavated in the Tptpll (Board et al. 2002 [157756]). The main distinguishing characteristic among the lithophysal and nonlithophysal units is the percentage of large scale (cm-m) voids within the rock. The Tptpul and Tptpll, as their names suggest, have a higher percentage of lithophysae than the Tptpmn and the Tptpln. Understanding the influence of the lithophysae is of great importance to understanding bulk thermal conductivity and perhaps repository system performance as well. To assess the spatial variability and uncertainty of thermal conductivity, a model is proposed that is functionally dependent on the volume fraction of lithophysae and the thermal conductivity of the matrix portion of the rock. In this model, void space characterized as lithophysae is assumed to be air-saturated under all conditions, while void space characterized as matrix may be either water- or air-saturated. Lithophysae are assumed to be air-saturated under all conditions since the units being studied are all located above the water table in the region of interest, and the relatively strong capillary forces of the matrix will, under most conditions, preferentially retain any moisture present in the rock.

  20. Determination of Thermoelectric Module Efficiency A Survey

    SciTech Connect (OSTI)

    Wang, Hsin [ORNL; McCarty, Robin [Marlow Industries, Inc; Salvador, James R. [GM R& D and Planning, Warren, Michigan; Yamamoto, Atsushi [AIST, Japan; Konig, Jan [Fraunhofer-Institute, Freiburg, Germany

    2014-01-01T23:59:59.000Z

    The development of thermoelectrics (TE) for energy conversion is in the transition phase from laboratory research to device development. There is an increasing demand to accurately determine the module efficiency, especially for the power generation mode. For many thermoelectrics, the figure of merit, ZT, of the material sometimes cannot be fully realized at the device level. Reliable efficiency testing of thermoelectric modules is important to assess the device ZT and provide the end-users with realistic values on how much power can be generated under specific conditions. We conducted a general survey of efficiency testing devices and their performance. The results indicated the lack of industry standards and test procedures. This study included a commercial test system and several laboratory systems. Most systems are based on the heat flow meter method and some are based on the Harman method. They are usually reproducible in evaluating thermoelectric modules. However, cross-checking among different systems often showed large errors that are likely caused by unaccounted heat loss and thermal resistance. Efficiency testing is an important area for the thermoelectric community to focus on. A follow-up international standardization effort is planned.

  1. New nano structure approaches for bulk thermoelectric materials

    E-Print Network [OSTI]

    Kim, Jeonghoon

    2010-01-01T23:59:59.000Z

    Thermoelectrics: Direct Solar Thermal Energy Conversion”,are working on solar thermal energy to generate electriccooling for CPUs, solar thermal energy harvesting, solid-

  2. Thermoelectric probe for Rashba spin-orbit interaction strength in a two dimensional electron gas

    E-Print Network [OSTI]

    S. K. Firoz Islam; Tarun Kanti Ghosh

    2012-07-18T23:59:59.000Z

    Thermoelectric coefficients of a two dimensional electron gas with the Rashba spin-orbit interaction are presented here. In absence of magnetic field, thermoelectric coefficients are enhanced due to the Rashba spin-orbit interaction. In presence of magnetic field, the thermoelectric coefficients of spin-up and spin-down electrons oscillate with different frequency and produces beating patterns in the components of the total thermoelectric power and the total thermal conductivity. We also provide analytical expressions of the thermoelectric coefficients to explain the beating pattern formation. We obtain a simple relation which determines the Rashba SOI strength if the magnetic fields corresponding to any two successive beat nodes are known from the experiment.

  3. Thermoelectric probe for Rashba spin-orbit interaction strength in a two dimensional electron gas

    E-Print Network [OSTI]

    Islam, S K Firoz

    2012-01-01T23:59:59.000Z

    Thermoelectric coefficients of a two dimensional electron gas with the Rashba spin-orbit interaction are presented here. In absence of magnetic field, thermoelectric coefficients are enhanced due to the Rashba spin-orbit interaction. In presence of magnetic field, the thermoelectric coefficients of spin-up and spin-down electrons oscillate with different frequency and produces beating patterns in the components of the total thermoelectric power and the total thermal conductivity. We also provide analytical expressions of the thermoelectric coefficients to explain the beating pattern formation. We obtain a simple relation which determines the Rashba SOI strength if the magnetic fields corresponding to any two successive beat nodes are known from the experiment.

  4. Improved maximum cooling by optimizing the geometry of thermoelectric leg elements Yan Zhang, Zhixi Bian and Ali Shakouri*

    E-Print Network [OSTI]

    , power factor; , thermal conductivity. Bi2Te3 has been the most popular thermoelectric material at room that in an idealized TEC model, the cooling power density is inversely proportional to the TE leg length. [4,5,6] We of single and multi stage TE devices. Nomenclature Seebeck coefficient electrical conductivity thermal

  5. Thermal Energy Harvesting with Thermoelectrics for Self-powered Sensors: With Applications to Implantable Medical Devices, Body Sensor Networks and Aging in Place

    E-Print Network [OSTI]

    Chen, Alic

    2011-01-01T23:59:59.000Z

    Pu-238) radioisotope and a thermoelectric generator. The Pu-to radioisotopes. In designing thermoelectric generators for

  6. Overview of Thermoelectric Power Generation Technologies in Japan

    Broader source: Energy.gov [DOE]

    Discusses thermoelectric power generation technologies as applied to waste heat recovery, renewable thermal energy sources, and energy harvesting

  7. Role of Brownian Motion Hydrodynamics on Nanofluid Thermal Conductivity

    SciTech Connect (OSTI)

    W Evans, J Fish, P Keblinski

    2005-11-14T23:59:59.000Z

    We use a simple kinetic theory based analysis of heat flow in fluid suspensions of solid nanoparticles (nanofluids) to demonstrate that the hydrodynamics effects associated with Brownian motion have a minor effect on the thermal conductivity of the nanofluid. Our conjecture is supported by the results of molecular dynamics simulations of heat flow in a model nanofluid with well-dispersed particles. Our findings are consistent with the predictions of the effective medium theory as well as with recent experimental results on well dispersed metal nanoparticle suspensions.

  8. The Thermal Conductivity of Low Density Concretes Containing Perlite 

    E-Print Network [OSTI]

    Yarbrough, D. W.

    1985-01-01T23:59:59.000Z

    -Tov, "HEATING5 - An IBM 360 Heat Conduction Program," ORNL/CSD/tm-15(1977). Oak Ridge National Laboratory, Oak Ridge, TN 37831. [5J Expanded Shale Clay and Slate Institute, "Lightweight Concrete Information Sheet," No.4, Washington, D.C., 1958. [6J Moore..., J. P., R. S. Graves, J. G. Stradley, J. H. Hannah, and D. L. McElroy, "Some Thermal Transport Properties of a Limestone Concrete," ORNL/TM-2644 (August 1969), Oak Ridge National Laboratory, Oak Ridge, TN 37831. [7J Valore, R. C., Jr., "Cellular...

  9. Synthesis and Characterization of Polymer Composites Containing Aligned Conducting Polymers and Carbon Nanotubes

    E-Print Network [OSTI]

    Manda, Swathi

    2014-04-21T23:59:59.000Z

    Field effect transistor Ge Germanium HOMO Highest occupied molecular orbital I-V Current vs. Voltage ? Total thermal conductivity ?e Electronic contribution of thermal conductivity L Length xiv LC Liquid Crystal LED Light emitting diode LUMO... feasible for applications in organic light emitting diodes, photovoltaics6 and more recently, thermoelectric devices. Traditional inorganic semi-conductor materials like Bismuth (Bi), Te and Selenium (Se) deliver high thermoelectric power and deliver...

  10. Experimental Investigation of Size Effects on the Thermal Conductivity of Silicon-Germanium Alloy Thin Films

    E-Print Network [OSTI]

    Cheaito, Ramez

    We experimentally investigate the role of size effects and boundary scattering on the thermal conductivity of silicon-germanium alloys. The thermal conductivities of a series of epitaxially grown Si[subscript 1-x] Ge[subscript ...

  11. Design of a steady state thermal conductivity measurement device for CNT RET polymer composites

    E-Print Network [OSTI]

    Louie, Brian Ming

    2011-01-01T23:59:59.000Z

    NY: Taylor & Francis. [10] Tritt, T. M. (2004). MeasurementBulk Materials. In T. M. Tritt, Thermal Conductivity Theory,

  12. Improved Thermo-Electric Efficiency through Decreased Thermal Conductivity due to Engineered Nano-Structures

    E-Print Network [OSTI]

    Vardi, Amichay

    transparent polycrystalline YAG specimens by means of the Spark Plasma Sintering (SPS) technique. The presence

  13. Fundamental Studies on the Effects of Microstructure on Thermal Conductivity in Nano-Thermoelectric Materials

    E-Print Network [OSTI]

    Alaniz, Joseph Edward

    2013-01-01T23:59:59.000Z

    energy created through burning fossil fuels, leading to an estimated equivalent waste of approximately 200 million gallons of gasoline from light

  14. Spatially localized measurement of thermal conductivity using a hybrid photothermal technique

    SciTech Connect (OSTI)

    David H Hurley; Marat Khafizov; Zilong Hua; Rory Kennedy; Heng Ban

    2012-05-01T23:59:59.000Z

    A photothermal technique capable of measuring thermal conductivity with micrometer lateral resolution is presented. This technique involves measuring separately the thermal diffusivity, D, and thermal effusivity, e, to extract the thermal conductivity, k=(e2/D)1/2. To generalize this approach, sensitivity analysis was conducted for materials having a range of thermal conductivities. Experimental validation was sought using two substrate materials, SiO2 and CaF2, both coated with thin titanium films. The measured conductivities compare favorably with literature values.

  15. Measurement of the thermoelectric properties of quasicrystalline AlPdRe and AlCuFe alloys

    SciTech Connect (OSTI)

    Wilson, M.L.; LeGault, S.; Stroud, R.M.; Tritt, T.M.

    1997-07-01T23:59:59.000Z

    The authors report the measurement of the thermal conductivity, electrical resistivity, and thermoelectric power on two quasicrystalline compounds, Al{sub 70}Pd{sub 20}Re{sub 10} and Al{sub 62.5}Cu{sub 25}Fe{sub 12.5}. These materials are found to possess a thermal conductivity of order 1 W/m{center{underscore}dot}K, while retaining their semimetallic conductivity. These features coupled with moderately large thermopowers, up to 55 {micro}V/K, imply that the general class of quasicrystalline compounds warrants careful investigation for their potential as new thermoelectric materials.

  16. MODEL FOR DETERMINING THE EFFECTIVE THERMAL CONDUCTIVITY OF PARTICLE BEDS WITH HIGH SOLID-TO-GAS THERMAL

    E-Print Network [OSTI]

    Abdou, Mohamed

    -TO-GAS THERMAL CONDUCTIVITY RATIO A.R. Raffray, Z. Gorbis, A. Badawi, M.S. Tillack, A.Y. Ying, and M. A. Abdou

  17. Solid state transport-based thermoelectric converter

    DOE Patents [OSTI]

    Hu, Zhiyu

    2010-04-13T23:59:59.000Z

    A solid state thermoelectric converter includes a thermally insulating separator layer, a semiconducting collector and an electron emitter. The electron emitter comprises a metal nanoparticle layer or plurality of metal nanocatalyst particles disposed on one side of said separator layer. A first electrically conductive lead is electrically coupled to the electron emitter. The collector layer is disposed on the other side of the separator layer, wherein the thickness of the separator layer is less than 1 .mu.m. A second conductive lead is electrically coupled to the collector layer.

  18. Anomalous thermal conduction characteristics of phase change composites with single walled carbon nanotube inclusions

    E-Print Network [OSTI]

    Maruyama, Shigeo

    , solar energy storage, etc.1, 2 The latent heat energy storages requires high thermal conductivity to the presence of exfoliated graphite nanoplatelets. Thermal energy storages using phase change materials of the phase change materials, because low thermal conductivity hinders the rate of energy storage and release

  19. ENS'07 Paris, France, 3-4 December 2007 MEASUREMENTS OF THERMAL CONDUCTIVITY OF ALUMINUM NANOPOWDERS

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    ENS'07 Paris, France, 3-4 December 2007 MEASUREMENTS OF THERMAL CONDUCTIVITY OF ALUMINUM spectroscopy (PAS) as a powerful technique to estimate thermal properties of aluminum nanosized powders. Aluminum nanopowders are considered as effective constituents of energetic materials. Thermal conductivity

  20. Thermoelectric Behavior of Flexible Organic Nanocomposites with Carbon Nanotubes 

    E-Print Network [OSTI]

    Choi, Kyung Who

    2013-12-03T23:59:59.000Z

    There have been significant researches about thermoelectric behaviors by applying carbon nanotube (CNT)/polymer nanocomposites. Due to its thermally disconnected but electrically connected junctions between CNTs, the thermoelectric properties were...

  1. Evaluation of Candidate In-Pile Thermal Conductivity Techniques

    SciTech Connect (OSTI)

    B. Fox; H. Ban; J. Daw; K. Condie; D. Knudson; J. Rempe

    2009-05-01T23:59:59.000Z

    Thermophysical properties of materials must be known for proper design, test, and application of new fuels and structural properties in nuclear reactors. In the case of nuclear fuels during irradiation, the physical structure and chemical composition change as a function of time and position within the rod. Typically, thermal conductivity changes, as well as other thermophysical properties being evaluated during irradiation in a materials and test reactor, are measured out-of-pile in “hot-cells.” Repeatedly removing samples from a test reactor to make out-of-pile measurements is expensive, has the potential to disturb phenomena of interest, and only provide understanding of the sample's end state at the time each measurement is made. There are also limited thermophysical property data for advanced fuels. Such data are needed for the development of next generation reactors and advanced fuels for existing nuclear plants. Having the capacity to effectively and quickly characterize fuels and material properties during irradiation has the potential to improve the fidelity of nuclear fuel data and reduce irradiation testing costs.

  2. Thermal conductivity measurements of insulators for fusion blankets

    SciTech Connect (OSTI)

    Horn, F.L.; Fillo, J.A.; Powell, J.R.

    1981-01-01T23:59:59.000Z

    Alumina-silica mat (8 lb/ft/sup 3/) varied in thermal conductivity in air and Ar from 0.06 W/m- K at 300/sup 0/C to 0.22 W/m- K at 1000/sup 0/C, but in He it increased to 0.24 W/m- K at 300/sup 0/C and 0.54 W/m- K at 1000/sup 0/C, while in steam it was about midway between these values. The carbon and graphite felts behaved similarly, but the rigid and denser (24 lb/ft/sup 3/) zirconia fiberboard exhibited superior insulating properties: 0.07 W/m- K at 300/sup 0/C and 0.14 W/m- K at 1000/sup 0/C in air and Ar, and 0.13 W/m- K at 300/sup 0/C and 0.17 W/m- K at 1000/sup 0/C in steam, but rising to 0.15 W/m- K at 300/sup 0/C and 0.49 W/m- K at 1000/sup 0/C in He. The lighter zirconia felt (14 lb/ft/sup 3/) in steam at 1000/sup 0/C was thought to be best at 0.23 W/m- K and only 0.40 W/m- K in He at 1000/sup 0/C.

  3. Reexamination of Basal Plane Thermal Conductivity of Suspended Graphene Samples Measured by Electro-Thermal Micro-Bridge Methods

    SciTech Connect (OSTI)

    Jo, Insun [University of Texas at Austin; Pettes, Michael [University of Connecticut, Storrs; Lindsay, Lucas R [ORNL; Ou, Eric [University of Texas at Austin; Weathers, Annie [University of Texas at Austin; Moore, Arden [Louisiana Tech University; Yao, Zhen [University of Texas at Austin; Shi, Li [University of Texas at Austin

    2015-01-01T23:59:59.000Z

    Thermal transport in suspended graphene samples has been measured in prior works and this work with the use of a suspended electro-thermal micro-bridge method. These measurement results are analyzed here to evaluate and eliminate the errors caused by the extrinsic thermal contact resistance. It is noted that the thermal resistance measured in a recent work increases linearly with the suspended length of the single-layer graphene samples synthesized by chemical vapor deposition (CVD), and that such a feature does not reveal the failure of Fourier s law despite the increase in the apparent thermal conductivity with length. The re-analyzed thermal conductivity of a single-layer CVD graphene sample reaches about ( 1680 180 )Wm-1K-1 at room temperature, which is close to the highest value reported for highly oriented pyrolytic graphite. In comparison, the thermal conductivity values measured for two suspended exfoliated bi-layer graphene samples are about ( 880 60 ) and ( 730 60 ) Wm-1K-1 at room temperature, and approach that of the natural graphite source above room temperature. However, the low-temperature thermal conductivities of these suspended graphene samples are still considerably lower than the graphite values, with the peak thermal conductivities shifted to much higher temperatures. Analysis of the thermal conductivity data reveals that the low temperature behavior is dominated by phonon scattering by polymer residue instead of by the lateral boundary.

  4. Semiconducting glasses: A new class of thermoelectric materials?

    SciTech Connect (OSTI)

    Goncalves, A.P., E-mail: apg@itn.pt [Instituto Tecnologico e Nuclear, Instituto Superior Tecnico, Universidade Tecnica de Lisboa/CFMC-UL, P-2686-953 Sacavem (Portugal); Lopes, E.B. [Instituto Tecnologico e Nuclear, Instituto Superior Tecnico, Universidade Tecnica de Lisboa/CFMC-UL, P-2686-953 Sacavem (Portugal)] [Instituto Tecnologico e Nuclear, Instituto Superior Tecnico, Universidade Tecnica de Lisboa/CFMC-UL, P-2686-953 Sacavem (Portugal); Delaizir, G. [SPCTS, UMR CNRS 7315, Centre Europeen de la Ceramique, 12 rue Atlantis, 87068 Limoges (France)] [SPCTS, UMR CNRS 7315, Centre Europeen de la Ceramique, 12 rue Atlantis, 87068 Limoges (France); Vaney, J.B.; Lenoir, B. [Institut Jean Lamour, UMR 7198 CNRS-Nancy Universite-UPVM, Ecole Nationale Superieure des Mines de Nancy, Parc de Saurupt, F-54042 Nancy (France)] [Institut Jean Lamour, UMR 7198 CNRS-Nancy Universite-UPVM, Ecole Nationale Superieure des Mines de Nancy, Parc de Saurupt, F-54042 Nancy (France); Piarristeguy, A.; Pradel, A. [Institut Charles Gerhardt (ICG), UMR 5253 CNRS, Universite de Montpellier 2, 34095 Montpellier (France)] [Institut Charles Gerhardt (ICG), UMR 5253 CNRS, Universite de Montpellier 2, 34095 Montpellier (France); Monnier, J.; Ochin, P.; Godart, C. [CNRS, ICMPE, CMTR, 2/8 rue Henri Dunant, 94320 Thiais (France)] [CNRS, ICMPE, CMTR, 2/8 rue Henri Dunant, 94320 Thiais (France)

    2012-09-15T23:59:59.000Z

    The deeper understanding of the factors that affect the dimensionless figure of merit, ZT, and the use of new synthetic methods has recently led to the development of novel systems with improved thermoelectric performances. Albeit up to now with ZT values lower than the conventional bulk materials, semiconducting glasses have also emerged as a new family of potential thermoelectric materials. This paper reviews the latest advances on semiconducting glasses for thermoelectric applications. Key examples of tellurium-based glasses, with high Seebeck coefficients, very low thermal conductivities and tunable electrical conductivities, are presented. ZT values as high as 0.2 were obtained at room temperature for several tellurium-based glasses with high copper concentrations, confirming chalcogenide semiconducting glasses as good candidates for high-performance thermoelectric materials. However, the temperature stability and electrical conductivity of the reported glasses are still not good enough for practical applications and further studies are still needed to enhance them. - Graphical abstract: Power factor as a function of the temperature for the Cu{sub 27.5}Ge{sub 2.5}Te{sub 70} and Cu{sub 30}As{sub 15}Te{sub 55} seniconducting glasses. Highlights: Black-Right-Pointing-Pointer A review of semiconducting glasses for thermoelectrics applications is presented. Black-Right-Pointing-Pointer The studied semiconducting glasses present very low thermal conductivities. Black-Right-Pointing-Pointer Composition can tune electrical conductivity and Seebeck coefficient. Black-Right-Pointing-Pointer ZT=0.2 is obtained at 300 K for different semiconducting glasses.

  5. Fractal-like tree networks reducing the thermal conductivity Boming Yu1,

    E-Print Network [OSTI]

    Li, Baowen

    Fractal-like tree networks reducing the thermal conductivity Boming Yu1, * and Baowen Li1,2 1 conductivity of composites with embedded self-similar H-shaped fractal-like tree networks is studied that the thermal conductivity of the H-shaped fractal-like tree networks does not obey Murray's law. The present

  6. Computational modeling of thermal conductivity of single walled carbon nanotube polymer composites

    E-Print Network [OSTI]

    Maruyama, Shigeo

    was developed to study the thermal conductivity of single walled carbon nanotube (SWNT)-polymer composites1 Computational modeling of thermal conductivity of single walled carbon nanotube polymer resistance on effective conductivity of composites were quantified. The present model is a useful tool

  7. Thermoelectric module

    DOE Patents [OSTI]

    Kortier, William E. (Columbus, OH); Mueller, John J. (Columbus, OH); Eggers, Philip E. (Columbus, OH)

    1980-07-08T23:59:59.000Z

    A thermoelectric module containing lead telluride as the thermoelectric mrial is encapsulated as tightly as possible in a stainless steel canister to provide minimum void volume in the canister. The lead telluride thermoelectric elements are pressure-contacted to a tungsten hot strap and metallurgically bonded at the cold junction to iron shoes with a barrier layer of tin telluride between the iron shoe and the p-type lead telluride element.

  8. Ceramic materials with low thermal conductivity and low coefficients of thermal expansion

    DOE Patents [OSTI]

    Brown, Jesse (Christiansburg, VA); Hirschfeld, Deidre (Elliston, VA); Liu, Dean-Mo (Blacksburg, VA); Yang, Yaping (Blacksburg, VA); Li, Tingkai (Blacksburg, VA); Swanson, Robert E. (Blacksburg, VA); Van Aken, Steven (Blacksburg, VA); Kim, Jin-Min (Seoul, KR)

    1992-01-01T23:59:59.000Z

    Compositions having the general formula (Ca.sub.x Mg.sub.1-x)Zr.sub.4 (PO.sub.4).sub.6 where x is between 0.5 and 0.99 are produced by solid state and sol-gel processes. In a preferred embodiment, when x is between 0.5 and 0.8, the MgCZP materials have near-zero coefficients of thermal expansion. The MgCZPs of the present invention also show unusually low thermal conductivities, and are stable at high temperatures. Macrostructures formed from MgCZP are useful in a wide variety of high-temperature applications. In a preferred process, calcium, magnesium, and zirconium nitrate solutions have their pH adjusted to between 7 and 9 either before or after the addition of ammonium dihydrogen phosphate. After dehydration to a gel, and calcination at temperatures in excess of 850.degree. C. for approximately 16 hours, single phase crystalline MgCZP powders with particle sizes ranging from approximately 20 nm to 50 nm result. The MgCZP powders are then sintered at temperatures ranging from 1200.degree. C. to 1350.degree. C. to form solid macrostructures with near-zero bulk coefficients of thermal expansion and low thermal conductivities. Porous macrostructures of the MgCZP powders of the present invention are also formed by combination with a polymeric powder and a binding agent, and sintering at high temperatures. The porosity of the resulting macrostructures can be adjusted by varying the particle size of the polymeric powder used.

  9. New equation calculates thermal conductivities of C[sub 1]-C[sub 4] gases

    SciTech Connect (OSTI)

    Yaws, C.L.; Lin, X.; Bu, L.; Nijhawan, S. (Lamar Univ., Beaumont, TX (United States))

    1994-04-18T23:59:59.000Z

    In the design of heat exchangers, heat-transfer coefficients are commonly calculated for individual items. These calculations require knowledge of the thermal conductivities of the species involved. The calculation require knowledge of the thermal conductivities of the species involved. The calculation of the overall heat-transfer coefficient for a heat exchanger also requires thermal conductivity data for the individual species. In fact, thermal conductivity is the fundamental property involved in heat transfer. Ordinarily, thermal conductivities are either measured experimentally or estimated using complex correlations and models. Engineers must search existing literature for the values needed. Here, a compilation of thermal conductivity data for gases is presented for a wide temperature range. Using these data with the accompanying equation will enable engineers to quickly determine values at the desired temperatures. The results are provided in an easy-to-use tabular format, which is especially helpful for rapid calculations using a personal computer or hand-held calculator.

  10. The measurement of thermal conductivity of jelly from 25 to 95 C

    E-Print Network [OSTI]

    Chen, Yih-Rong

    1985-01-01T23:59:59.000Z

    line heat source method, the thermal con- ductivities of a jelly model (unflavored jelly), sugar solution and some commercial jelly products were measured. The studies were conducted in the temperature range from 25 to 95 'C. Thermal conductivity... were developed from experimental data for unflavored jelly and sugar solutions to predict the thermal conductivity of commercially available fruit jellies at various moisture contents. The predicted values obtained were statistically compared...

  11. Thermal conductivity of configurable two-dimensional carbon nanotube architecture and strain modulation

    SciTech Connect (OSTI)

    Zhan, H. F.; Bell, J. M.; Gu, Y. T., E-mail: yuantong.gu@qut.edu.au [School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, 2 George St., Brisbane, Queensland 4000 (Australia); Zhang, G. [Institute of High Performance Computing, Agency for Science, Technology and Research, 1 Fusionopolis Way, Singapore 138632 (Singapore)

    2014-10-13T23:59:59.000Z

    We reported the thermal conductivity of the two-dimensional carbon nanotube (CNT)-based architecture, which can be constructed through welding of single-wall CNTs by electron beam. Using large-scale nonequilibrium molecular dynamics simulations, the thermal conductivity is found to vary with different junction types due to their different phonon scatterings at the junction. The strong length and strain dependence of the thermal conductivity suggests an effective avenue to tune the thermal transport properties of the CNT-based architecture, benefiting the design of nanoscale thermal rectifiers or phonon engineering.

  12. Thermoelectric materials -- New directions and approaches. Materials Research Society symposium proceedings, Volume 478

    SciTech Connect (OSTI)

    Tritt, T.M.; Kanatzidis, M.G.; Lyon, H.B. Jr.; Mahan, G.D. [eds.

    1997-07-01T23:59:59.000Z

    Thermoelectric materials are utilized in a wide variety of applications related to solid-state refrigeration or small-scale power generation. Thermoelectric cooling is an environmentally friendly method of small-scale cooling in specific applications such as cooling computer chips and laser diodes. Thermoelectric materials are used in a wide range of applications from beverage coolers to power generation for deep-space probes such as the Voyager missions. Over the past thirty years, alloys based on the Bi-Te systems {l{underscore}brace}(Bi{sub 1{minus}x}Sb{sub x}){sub 2} (Te{sub 1{minus}x}Se{sub x}){sub 3}{r{underscore}brace} and Si{sub 1{minus}x}Ge{sub x} systems have been extensively studied and optimized for their use as thermoelectric materials to perform a variety of solid-state thermoelectric refrigeration and power generation tasks. Despite this extensive investigation of the traditional thermoelectric materials, there is still a substantial need and room for improvement, and thus, entirely new classes of compounds will have to be investigated. Over the past two-to-three years, research in the field of thermoelectric materials has been undergoing a rapid rebirth. The enhanced interest in better thermoelectric materials has been driven by the need for much higher performance and new temperature regimes for thermoelectric devices in many applications. The essence of a good thermoelectric is given by the determination of the material's dimensionless figure of merit, ZT = ({alpha}{sup 2}{sigma}/{lambda})T, where {alpha} is the Seebeck coefficient, {sigma} the electrical conductivity and {lambda} the total thermal conductivity. The best thermoelectric materials have a value of ZT = 1. This ZT = 1 has been an upper limit for more than 30 years, yet no theoretical or thermodynamic reason exits for why it can not be larger. The focus of the symposium is embodied in the title, Thermoelectric Materials: New Directions and Approaches. Many of the researchers in the field believe that future advances in thermoelectric applications will come through research in new materials. The authors have many new methods of materials synthesis and much more rapid characterization of these materials than were available 20--30 years ago. They have tried to focus the symposium on new directions and new materials such as skutterudites, quantum well and superlattice structures, new metal chalcogenides, rare earth systems, and quasicrystals. Other new materials are also presented in these proceedings. Separate abstracts were prepared for all the papers in this volume.

  13. Anomalously increased effective thermal conductivities of ethylene glycol-based nanofluids containing copper nanoparticles

    SciTech Connect (OSTI)

    Eastman, J. A.; Choi, S. U. S.; Li, S.; Yu, W.; Thompson, L. J.

    2001-02-05T23:59:59.000Z

    It is shown that a ''nanofluid'' consisting of copper nanometer-sized particles dispersed in ethylene glycol has a much higher effective thermal conductivity than either pure ethylene glycol or ethylene glycol containing the same volume fraction of dispersed oxide nanoparticles. The effective thermal conductivity of ethylene glycol is shown to be increased by up to 40% for a nanofluid consisting of ethylene glycol containing approximately 0.3 vol% Cu nanoparticles of mean diameter <10 nm. The results are anomalous based on previous theoretical calculations that had predicted a strong effect of particle shape on effective nanofluid thermal conductivity, but no effect of either particle size or particle thermal conductivity.

  14. Thermoelectric measurement equipments This instrument is designed for simultaneous measurement of Seebeck coefficient and

    E-Print Network [OSTI]

    Taya, Minoru

    measurement of Seebeck coefficient and electric conductivity for the evaluation of thermoelectric electromotive force. · Employment of an infrared gold image heating furnace that excels in temperature.1 msec/0.3 msec or less Sensor Thermocouple Thermocouple, IR detector Measurement Thermal diffusivity

  15. angle-resolved thermal conductivity: Topics by E-print Network

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    conductivity in the range (4.84 ( 0.44) ? 103 to (5.30 ( 0 72 THERMAL CONDUCTIVITY OF HEMP CONCRETES: VARIATION WITH FORMULATION, DENSITY AND Mathematics Websites Summary:...

  16. Tuning Interfacial Thermal Conductance of Graphene Embedded in Soft Materials by Vacancy Defects

    SciTech Connect (OSTI)

    Liu, Ying [Clemson University; Hu, Chongze [Clemson University; Huang, Jingsong [ORNL; Sumpter, Bobby G [ORNL; Qiao, Rui [Engineering Science and Mechanics Department, Virginia Tech, Blacksburg, VA, USA

    2015-01-01T23:59:59.000Z

    Nanocomposites based on graphene dispersed in matrices of soft materials are promising thermal management materials. Their effective thermal conductivity depends on both the thermal conductivity of graphene and the conductance of the thermal transport across graphene-matrix interfaces. Here we report on molecular dynamics simulations of the thermal transport across the interfaces between defected graphene and soft materials in two different modes: in the across mode, heat enters graphene from one side of its basal plane and leaves through the other side; in the non-across mode, heat enters or leaves a graphene simultaneously from both sides of its basal plane. We show that, as the density of vacancy defects in graphene increases from 0 to 8%, the conductance of the interfacial thermal transport in the across mode increases from 160.4 16 to 207.8 11 MW/m2K, while that in the non-across mode increases from 7.2 0.1 to 17.8 0.6 MW/m2K. The molecular mechanisms for these variations of thermal conductance are clarified by using the phonon density of states and structural characteristics of defected graphenes. On the basis of these results and effective medium theory, we show that it is possible to enhance the effective thermal conductivity of thermal nanocomposites by tuning the density of vacancy defects in graphene despite the fact that graphene s thermal conductivity always decreases as vacancy defects are introduced.

  17. Electrical properties and figures of merit for new chalcogenide-based thermoelectric materials

    SciTech Connect (OSTI)

    Schindler, J.L.; Hogan, T.P.; Brazis, P.W.; Kannewurf, C.R.; Chung, D.Y.; Kanatzidis, M.G.

    1997-07-01T23:59:59.000Z

    New Bi-based chalcogenide compounds have been prepared using the polychalcogenide flux technique for crystal growth. These materials exhibit characteristics of good thermoelectric materials. Single crystals of the compound CsBi{sub 4}Te{sub 6} have shown conductivity as high as 2440 S/cm with a p-type thermoelectric power of {approx}+110 {micro}V/K at room temperature. A second compound, {beta}-K{sub 2}Bi{sub 8}Se{sub 13} shows lower conductivity {approx}240 S/cm, but a larger n-type thermopower {approx}{minus}200 {micro}V/K. Thermal transport measurements have been performed on hot-pressed pellets of these materials and the results show comparable or lower thermal conductivities than Bi{sub 2}Te{sub 3}. This improvement may reflect the reduced lattice symmetry of the new chalcogenide thermoelectrics. The thermoelectric figure of merit for CsBi{sub 4}Te{sub 6} reaches ZT {approx} 0.32 at 260 K and for {beta}-K{sub 2}Bi{sub 8}Se{sub 13} ZT {approx} 0.32 at room temperature, indicating that these compounds are viable candidates for thermoelectric refrigeration applications.

  18. Finding New Thermoelectric Compounds Using Crystallographic Data: Atomic Displacement Parameters

    SciTech Connect (OSTI)

    Chakoumakos, B.C.; Mandrus, D.G.; Sales, B.C.; Sharp, J.W.

    1999-08-29T23:59:59.000Z

    A new structure-property relationship is discussed which links atomic displacement parameters (ADPs) and the lattice thermal conductivity of clathrate-like compounds. For many clathrate-like compounds, in which one of the atom types is weakly bound and ''rattles'' within its atomic cage, room temperature ADP information can be used to estimate the room temperature lattice thermal conductivity, the vibration frequency of the ''rattler'', and the temperature dependence of the heat capacity. Neutron data and X-ray crystallography data, reported in the literature, are used to apply this analysis to several promising classes of thermoelectric materials.

  19. NSF/DOE Thermoelectrics Partnership: Thermoelectrics for Automotive...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Thermoelectrics for Automotive Waste Heat Recovery NSFDOE Thermoelectrics Partnership: Thermoelectrics for Automotive Waste Heat Recovery Development for commercialization of...

  20. Sound Waves, Thermal Conduction, and the Continuity Equation Carl Sovinec, T-15 LANL

    E-Print Network [OSTI]

    Sovinec, Carl

    Sound Waves, Thermal Conduction, and the Continuity Equation Carl Sovinec, T-15 LANL 8 to sound waves when we use thermal conduction in our system of equations without continuity. The fluid definitions 0 02 p c , defining c as the adiabatic sound speed, kc 1 , the time for the adiabatic wave

  1. Thermal conductivity of nitrogenated ultrananocrystalline diamond films M. Shamsa,1,a

    E-Print Network [OSTI]

    , polycrystalline diamond PCD , diamondlike carbon DLC , carbon nanotubes, and single-layer graphene, have recentlyThermal conductivity of nitrogenated ultrananocrystalline diamond films on silicon M. Shamsa,1,a S of nitrogenated ultrananocrystalline diamond UNCD films on silicon. For better accuracy, the thermal conductivity

  2. Computational analysis of the thermal conductivity of the carboncarbon composite materials

    E-Print Network [OSTI]

    Grujicic, Mica

    Computational analysis of the thermal conductivity of the carbon­carbon composite materials M Abstract Experimental data for carbon­carbon con- stituent materials are combined with a three and longitudinal thermal conductivities in carbon­carbon composites. Particular attention is given in elucidating

  3. Study of thermal conductivity in organic solid wastes before composting J. HUET, C. Druilhe, G. Debenest

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Study of thermal conductivity in organic solid wastes before composting J. HUET, C. Druilhe, G. Debenest ORBIT2012 1 STUDY OF THERMAL CONDUCTIVITY IN ORGANIC SOLID WASTES BEFORE COMPOSTING J. Huet and disposal. Composting can be defined as the process whereby aerobic micro-organisms convert organic

  4. Role of Brownian motion hydrodynamics on nanofluid thermal conductivity William Evans

    E-Print Network [OSTI]

    Fish, Jacob

    Role of Brownian motion hydrodynamics on nanofluid thermal conductivity William Evans Lockheed of solid nanoparticles nanofluids to demonstrate that the hydrodynamics effects associated with Brownian motion have only a minor effect on the thermal conductivity of the nanofluid. This analysis is supported

  5. ENHANCED THERMAL CONDUCTIVITY IN NANOFLUIDS UNDER THE ACTION OF OSCILLATING FORCE FIELDS

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    ENHANCED THERMAL CONDUCTIVITY IN NANOFLUIDS UNDER THE ACTION OF OSCILLATING FORCE FIELDS Clément Le forces in the radio frequency and microwave ranges, we show that the thermal conductivity of nanofluids. Active control of transport coefficients. Nanocolloïds. Cooling system Introduction Nanofluids (Eastman

  6. Computerized, Transient Hot-Wire Thermal Conductivity (HWTC) Apparatus for Nanofluids

    E-Print Network [OSTI]

    Kostic, Milivoje M.

    Computerized, Transient Hot-Wire Thermal Conductivity (HWTC) Apparatus for Nanofluids M. KOSTIC for thermal conductivity measurements of common fluids and nanofluids has been recently developed, designed nanofluids of 1 % volumetric concentration of 35 nm size copper nanoparticles in ethylene glycol and in water

  7. Effect of bending buckling of carbon nanotubes on thermal conductivity of carbon nanotube materials

    E-Print Network [OSTI]

    Zhigilei, Leonid V.

    Effect of bending buckling of carbon nanotubes on thermal conductivity of carbon nanotube materials and lateral lattice strain states under a tensile load in as-reacted and prebent CuNb/Nb3Sn wires using;Effect of bending buckling of carbon nanotubes on thermal conductivity of carbon nanotube materials

  8. Discrete thermal element modelling of heat conduction in particle systems: Basic formulations

    E-Print Network [OSTI]

    Martin, Ralph R.

    methodology, termed the discrete thermal element method (DTEM), for the effec- tive modelling of heat rights reserved. Keywords: Discrete thermal element method; Circular particle; Thermal contact; Heat conduction; Boundary (integral) equation/element 1. Introduction Heat transfer in particle systems can

  9. Communication: Minimum in the thermal conductivity of supercooled water: A computer simulation study

    SciTech Connect (OSTI)

    Bresme, F., E-mail: f.bresme@imperial.ac.uk [Chemical Physics Section, Department of Chemistry, Imperial College, London SW7 2AZ, United Kingdom and Department of Chemistry, Norwegian University of Science and Technology, Trondheim 7491 (Norway); Biddle, J. W.; Sengers, J. V.; Anisimov, M. A. [Institute for Physical Science and Technology, and Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20742 (United States)] [Institute for Physical Science and Technology, and Department of Chemical and Biomolecular Engineering, University of Maryland, College Park, Maryland 20742 (United States)

    2014-04-28T23:59:59.000Z

    We report the results of a computer simulation study of the thermodynamic properties and the thermal conductivity of supercooled water as a function of pressure and temperature using the TIP4P-2005 water model. The thermodynamic properties can be represented by a two-structure equation of state consistent with the presence of a liquid-liquid critical point in the supercooled region. Our simulations confirm the presence of a minimum in the thermal conductivity, not only at atmospheric pressure, as previously found for the TIP5P water model, but also at elevated pressures. This anomalous behavior of the thermal conductivity of supercooled water appears to be related to the maximum of the isothermal compressibility or the minimum of the speed of sound. However, the magnitudes of the simulated thermal conductivities are sensitive to the water model adopted and appear to be significantly larger than the experimental thermal conductivities of real water at low temperatures.

  10. An Analytical Study Of A 2-Layer Transient Thermal Conduction...

    Open Energy Info (EERE)

    Typical interpretation schemes are based on simple, one-layer solutions to the Fourier conduction equation using the annual solar cycle as a surface heat source. We present...

  11. Computational modeling and analysis of thermoelectric properties of nanoporous silicon

    SciTech Connect (OSTI)

    Li, H.; Yu, Y.; Li, G., E-mail: gli@clemson.edu [Department of Mechanical Engineering, Clemson University, Clemson, South Carolina 29634-0921 (United States)

    2014-03-28T23:59:59.000Z

    In this paper, thermoelectric properties of nanoporous silicon are modeled and studied by using a computational approach. The computational approach combines a quantum non-equilibrium Green's function (NEGF) coupled with the Poisson equation for electrical transport analysis, a phonon Boltzmann transport equation (BTE) for phonon thermal transport analysis and the Wiedemann-Franz law for calculating the electronic thermal conductivity. By solving the NEGF/Poisson equations self-consistently using a finite difference method, the electrical conductivity ? and Seebeck coefficient S of the material are numerically computed. The BTE is solved by using a finite volume method to obtain the phonon thermal conductivity k{sub p} and the Wiedemann-Franz law is used to obtain the electronic thermal conductivity k{sub e}. The figure of merit of nanoporous silicon is calculated by ZT=S{sup 2}?T/(k{sub p}+k{sub e}). The effects of doping density, porosity, temperature, and nanopore size on thermoelectric properties of nanoporous silicon are investigated. It is confirmed that nanoporous silicon has significantly higher thermoelectric energy conversion efficiency than its nonporous counterpart. Specifically, this study shows that, with a n-type doping density of 10{sup 20}?cm{sup –3}, a porosity of 36% and nanopore size of 3 nm ×?3?nm, the figure of merit ZT can reach 0.32 at 600?K. The results also show that the degradation of electrical conductivity of nanoporous Si due to the inclusion of nanopores is compensated by the large reduction in the phonon thermal conductivity and increase of absolute value of the Seebeck coefficient, resulting in a significantly improved ZT.

  12. Hot wire needle probe for in-reactor thermal conductivity measurement

    SciTech Connect (OSTI)

    JE Daw; JL Rempe; DL Knudson

    2012-08-01T23:59:59.000Z

    Thermal conductivity is a key property that must be known for proper design, test, and application of new fuels and structural materials in nuclear reactors. Thermal conductivity is highly dependent on the physical structure, chemical composition, and the state of the material. Typically, thermal conductivity changes that occur during irradiation are measured out-of-pile by Post Irradiated Examination (PIE) using a “cook and look” approach in hot-cells. Repeatedly removing samples from a test reactor to make out-of-pile measurements is expensive, has the potential to disturb phenomena of interest, and only provides understanding of the sample's end state at the time each measurement is made. There are also limited thermophysical property data for advanced fuels. Such data are needed for simulation design codes, the development of next generation reactors, and advanced fuels for existing nuclear plants. Being able to quickly characterize fuel thermal conductivity during irradiation can improve the fidelity of data, reduce costs of post-irradiation examinations, increase understanding of how fuels behave under irradiation, and confirm or improve existing thermal conductivity measurement techniques. This paper discusses recent efforts to develop and evaluate an in-pile thermal conductivity sensor based on a hot wire needle probe. Testing has been performed on samples with thermal conductivities ranging from 0.2 W/m-K to 22 W-m-K in temperatures ranging from 20 °C to 600 °C. Thermal conductivity values measured using the needle probe match data found in the literature to within 5% for samples tested at room temperature, 5.67% for low thermal conductivity samples tested at high temperatures, and 10% for high thermal conductivity samples tested at high temperatures. Experimental results also show that this sensor is capable of operating in various test conditions and of surviving long duration irradiations.

  13. Thermal conductivity changes upon neutron transmutation of {sup 10}B doped diamond

    SciTech Connect (OSTI)

    Jagannadham, K., E-mail: jag-kasichainula@ncsu.edu [Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Verghese, K. [Nuclear Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States); Butler, J. E. [Code 6174, Naval research Laboratory, Washington, District of Columbia 20375 (United States)

    2014-08-28T23:59:59.000Z

    {sup 10}B doped p-type diamond samples were subjected to neutron transmutation reaction using thermal neutron flux of 0.9 × 10{sup 13} cm{sup ?2} s{sup ?1} and fast neutron flux of 0.09 × 10{sup 13} cm{sup ?2} s{sup ?1}. Another sample of epilayer grown on type IIa (110) single crystal diamond substrate was subjected to equal thermal and fast neutron flux of 10{sup 14}?cm{sup ?2} s{sup ?1}. The defects in the diamond samples were previously characterized by different methods. In the present work, thermal conductivity of these diamond samples was determined at room temperature by transient thermoreflectance method. The thermal conductivity change in the samples as a function of neutron fluence is explained by the phonon scattering from the point defects and disordered regions. The thermal conductivity of the diamond samples decreased more rapidly initially and less rapidly for larger neutron fluence. In addition, the thermal conductivity in type IIb diamond decreased less rapidly with thermal neutron fluence compared to the decrease in type IIa diamond subjected to fast neutron fluence. It is concluded that the rate of production of defects during transmutation reaction is slower when thermal neutrons are used. The thermal conductivity of epilayer of diamond subjected to high thermal and fast neutron fluence is associated with the covalent carbon network in the composite structure consisting of disordered carbon and sp{sup 2} bonded nanocrystalline regions.

  14. Thermoelectric properties of Weyl and Dirac semimetals

    E-Print Network [OSTI]

    Rex Lundgren; Pontus Laurell; Gregory A. Fiete

    2014-10-14T23:59:59.000Z

    We study the electronic contribution to the thermal conductivity and the thermopower of Weyl and Dirac semimetals using a semiclassical Boltzmann approach. We investigate the effect of various relaxation processes including disorder and interactions on the thermoelectric properties, and also consider doping away from the Weyl or Dirac point. We find that the thermal conductivity and thermopower have an interesting dependence on the chemical potential that is characteristic of the linear electronic dispersion, and that the electron-electron interactions modify the Lorenz number. For the interacting system, we also use the Kubo formalism to obtain the transport coefficients. We find exact agreement between the Kubo and Boltzmann approaches at high temperatures. We also consider the effect of electric and magnetic fields on the thermal conductivity in various orientations with respect to the temperature gradient. Notably, when the temperature gradient and magnetic field are parallel, we find a large contribution to the longitudinal thermal conductivity that is quadratic in the magnetic field strength, similar to the magnetic field dependence of the longitudinal electrical conductivity due to the presence of the chiral anomaly when no thermal gradient is present.

  15. Thermoelectric system

    DOE Patents [OSTI]

    Reiners, Eric A. (Washington, IL); Taher, Mahmoud A. (Peoria, IL); Fei, Dong (Peoria, IL); McGilvray, Andrew N. (East Peoria, IL)

    2007-10-30T23:59:59.000Z

    In one particular embodiment, an internal combustion engine is provided. The engine comprises a block, a head, a piston, a combustion chamber defined by the block, the piston, and the head, and at least one thermoelectric device positioned between the combustion chamber and the head. In this particular embodiment, the thermoelectric device is in direct contact with the combustion chamber. In another particular embodiment, a cylinder head configured to sit atop a cylinder bank of an internal combustion engine is provided. The cylinder head comprises a cooling channel configured to receive cooling fluid, valve seats configured for receiving intake and exhaust valves, and thermoelectric devices positioned around the valve seats.

  16. 1-Dimensional Numerical Model of Thermal Conduction and Vapor Diffusion

    E-Print Network [OSTI]

    Schörghofer, Norbert

    developed by Samar Khatiwala, 2001 extended to variable thermal properties and irregular grid by Norbert Sch for c. Upper boundary condition: a) Radiation Q + k T z z=0 = T4 z=0 Q is the incoming solar flux of Water Vapor with Phase Transitions developed by Norbert Sch¨orghofer, 2003­2004 3 phases: vapor, free

  17. Thermal conductivity profile determination in proton-irradiated ZrC by spatial and frequency scanning thermal wave methods

    SciTech Connect (OSTI)

    Jensen, C. [GRESPI, Multiscale Thermophysics Lab., Université de Reims Champagne-Ardenne URCA, Moulin de la Housse BP 1039, Reims 51687 (France) [GRESPI, Multiscale Thermophysics Lab., Université de Reims Champagne-Ardenne URCA, Moulin de la Housse BP 1039, Reims 51687 (France); Department of Mechanical and Aerospace Engineering, Utah State University, Logan, Utah 84322 (United States); Chirtoc, M.; Horny, N.; Antoniow, J. S.; Pron, H. [GRESPI, Multiscale Thermophysics Lab., Université de Reims Champagne-Ardenne URCA, Moulin de la Housse BP 1039, Reims 51687 (France)] [GRESPI, Multiscale Thermophysics Lab., Université de Reims Champagne-Ardenne URCA, Moulin de la Housse BP 1039, Reims 51687 (France); Ban, H. [Department of Mechanical and Aerospace Engineering, Utah State University, Logan, Utah 84322 (United States)] [Department of Mechanical and Aerospace Engineering, Utah State University, Logan, Utah 84322 (United States)

    2013-10-07T23:59:59.000Z

    Using complementary thermal wave methods, the irradiation damaged region of zirconium carbide (ZrC) is characterized by quantifiably profiling the thermophysical property degradation. The ZrC sample was irradiated by a 2.6 MeV proton beam at 600 °C to a dose of 1.75 displacements per atom. Spatial scanning techniques including scanning thermal microscopy (SThM), lock-in infrared thermography (lock-in IRT), and photothermal radiometry (PTR) were used to directly map the in-depth profile of thermal conductivity on a cross section of the ZrC sample. The advantages and limitations of each system are discussed and compared, finding consistent results from all techniques. SThM provides the best resolution finding a very uniform thermal conductivity envelope in the damaged region measuring ?52 ± 2 ?m deep. Frequency-based scanning PTR provides quantification of the thermal parameters of the sample using the SThM measured profile to provide validation of a heating model. Measured irradiated and virgin thermal conductivities are found to be 11.9 ± 0.5 W m{sup ?1} K{sup ?1} and 26.7 ±1 W m{sup ?1} K{sup ?1}, respectively. A thermal resistance evidenced in the frequency spectra of the PTR results was calculated to be (1.58 ± 0.1) × 10{sup ?6} m{sup 2} K W{sup ?1}. The measured thermal conductivity values compare well with the thermal conductivity extracted from the SThM calibrated signal and the spatially scanned PTR. Combined spatial and frequency scanning techniques are shown to provide a valuable, complementary combination for thermal property characterization of proton-irradiated ZrC. Such methodology could be useful for other studies of ion-irradiated materials.

  18. Thermal Conductivity Spectroscopy Technique to Measure Phonon Mean Free Paths

    E-Print Network [OSTI]

    Schmidt, A. J.

    Size effects in heat conduction, which occur when phonon mean free paths (MFPs) are comparable to characteristic lengths, are being extensively explored in many nanoscale systems for energy applications. Knowledge of MFPs ...

  19. Duality of the Interfacial Thermal Conductance in Graphene-based Nanocomposites

    SciTech Connect (OSTI)

    Liu, Ying [Clemson University] [Clemson University; Huang, Jingsong [ORNL] [ORNL; Yang, Bao [University of Maryland] [University of Maryland; Sumpter, Bobby G [ORNL] [ORNL; Qiao, Rui [Clemson University] [Clemson University

    2014-01-01T23:59:59.000Z

    The thermal conductance of graphene-matrix interfaces plays a key role in controlling the thermal transport properties of graphene-based nanocomposites. Using classical molecular dynamics simulations, we found that the interfacial thermal conductance depends strongly on the mode of heat transfer at the graphene-matrix interfaces: if heat enters graphene from one side of its basal plane and immediately leaves the graphene through the other side, the corresponding interfacial thermal conductance, G(across), is large; if heat enters graphene from both sides of its basal plane and leaves the graphene at a position far away on its basal plane, the corresponding interfacial thermal conductance, G(non-across), is small. For a single-layer graphene immersed in liquid octane, G(across) is ~150 MW/m2K while Gnon-across is ~5 MW/m2K. G(across) decreases with increasing multi-layer graphene thickness (i.e., number of layers in graphene) and approaches an asymptotic value of 100 MW/m2K for 7-layer graphenes. G(non-across) increases only marginally as the graphene sheet thickness increases. Such a duality of the interface thermal conductance for different probing methods and its dependence on graphene sheet thickness can be traced ultimately to the unique physical and chemical structure of graphene materials. The ramifications of these results in areas such as experimental measurement of thermal conductivity of graphene and the design of graphene-based thermal nanocomposites are discussed.

  20. Computational Efficient Upscaling Methodology for Predicting Thermal Conductivity of Nuclear Waste forms

    SciTech Connect (OSTI)

    Li, Dongsheng; Sun, Xin; Khaleel, Mohammad A.

    2011-09-28T23:59:59.000Z

    This study evaluated different upscaling methods to predict thermal conductivity in loaded nuclear waste form, a heterogeneous material system. The efficiency and accuracy of these methods were compared. Thermal conductivity in loaded nuclear waste form is an important property specific to scientific researchers, in waste form Integrated performance and safety code (IPSC). The effective thermal conductivity obtained from microstructure information and local thermal conductivity of different components is critical in predicting the life and performance of waste form during storage. How the heat generated during storage is directly related to thermal conductivity, which in turn determining the mechanical deformation behavior, corrosion resistance and aging performance. Several methods, including the Taylor model, Sachs model, self-consistent model, and statistical upscaling models were developed and implemented. Due to the absence of experimental data, prediction results from finite element method (FEM) were used as reference to determine the accuracy of different upscaling models. Micrographs from different loading of nuclear waste were used in the prediction of thermal conductivity. Prediction results demonstrated that in term of efficiency, boundary models (Taylor and Sachs model) are better than self consistent model, statistical upscaling method and FEM. Balancing the computation resource and accuracy, statistical upscaling is a computational efficient method in predicting effective thermal conductivity for nuclear waste form.

  1. eXtremes of heat conduction: Pushing the boundaries of the thermal

    E-Print Network [OSTI]

    Braun, Paul

    -called "nanofluids" (suspensions in liquids) ­ polymer composites and coatings Fischer (2007) Lehman (2005) #12;Critical aspect ratio for a fiber composite · Isotropic fiber composite with high conductivity fibers (andeXtremes of heat conduction: Pushing the boundaries of the thermal conductivity of materials David

  2. Proximity nanovalve with large phase-tunable thermal conductance

    SciTech Connect (OSTI)

    Strambini, E., E-mail: e.strambini@sns.it; Giazotto, F., E-mail: f.giazotto@sns.it [NEST Istituto Nanoscienze-CNR and Scuola Normale Superiore, I-56127 Pisa (Italy); Bergeret, F. S., E-mail: sebastian-bergeret@ehu.es [Centro de Física de Materiales (CFM-MPC), Centro Mixto CSIC-UPV/EHU, Manuel de Lardizabal 4, E-20018 San Sebastián (Spain); Donostia International Physics Center (DIPC), Manuel de Lardizabal 5, E-20018 San Sebastián (Spain); Institut für Physik, Carl von Ossietzky Universität, D-26111 Oldenburg (Germany)

    2014-08-25T23:59:59.000Z

    We propose a phase-controlled heat-flux quantum valve based on the proximity effect driven by a superconducting quantum interference proximity transistor (SQUIPT). Its operation relies on the phase-dependent quasiparticle density of states in the Josephson weak-link of the SQUIPT which controls thermal transport across the device. In a realistic Al/Cu-based setup the structure can provide efficient control of thermal current inducing temperature swings exceeding ?100?mK, and flux-to-temperature transfer coefficients up to ?500?mK/?{sub 0} below 100?mK. The nanovalve performances improve by lowering the bath temperature, making the proposed structure a promising building-block for the implementation of coherent caloritronic devices operating below 1?K.

  3. The thermal conductivity of rock under hydrothermal conditions: measurements and applications

    SciTech Connect (OSTI)

    Williams, Colin F.; Sass, John H.

    1996-01-24T23:59:59.000Z

    The thermal conductivities of most major rock-forming minerals vary with both temperature and confining pressure, leading to substantial changes in the thermal properties of some rocks at the high temperatures characteristic of geothermal systems. In areas with large geothermal gradients, the successful use of near-surface heat flow measurements to predict temperatures at depth depends upon accurate corrections for varying thermal conductivity. Previous measurements of the thermal conductivity of dry rock samples as a function of temperature were inadequate for porous rocks and susceptible to thermal cracking effects in nonporous rocks. We have developed an instrument for measuring the thermal conductivity of water-saturated rocks at temperatures from 20 to 350 °C and confining pressures up to 100 MPa. A transient line-source of heat is applied through a needle probe centered within the rock sample, which in turn is enclosed within a heated pressure vessel with independent controls on pore and confining pressure. Application of this technique to samples of Franciscan graywacke from The Geysers reveals a significant change in thermal conductivity with temperature. At reservoir-equivalent temperatures of 250 °C, the conductivity of the graywacke decreases by approximately 25% relative to the room temperature value. Where heat flow is constant with depth within the caprock overlying the reservoir, this reduction in conductivity with temperature leads to a corresponding increase in the geothermal gradient. Consequently, reservoir temperature are encountered at depths significantly shallower than those predicted by assuming a constant temperature gradient with depth. We have derived general equations for estimating the thermal conductivity of most metamorphic and igneous rocks and some sedimentary rocks at elevated temperature from knowledge of the room temperature thermal conductivity. Application of these equations to geothermal exploration should improve estimates of subsurface temperatures derived from heat flow measurements.

  4. 0-7803-XXXX-X/06/$20.00 2006 IEEE 22nd IEEE SEMI-THERM Symposium Hot Spot Cooling using Embedded Thermoelectric Coolers

    E-Print Network [OSTI]

    Thermoelectric Coolers G. Jeffrey Snyder, Marco Soto, Randy Alley, David Koester, Bob Conner Nextreme Thermal spot temperatures when efficiently integrated with a heat spreader. Embedded thermoelectric cooling (e by today's advanced processors. Keywords Localized hot spot cooling. Thermoelectric, Peltier Cooling

  5. Overview of Thermoelectric Power Generation Technologies in Japan...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    in Japan Discusses thermoelectric power generation technologies as applied to waste heat recovery, renewable thermal energy sources, and energy harvesting kajikawa.pdf...

  6. Misfit layer compounds and ferecrystals: Model systems for thermoelectric nanocomposites

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Merrill, Devin R. [Univ. of Oregon, Eugene, OR (United States); Moore, Daniel B. [Univ. of Oregon, Eugene, OR (United States); Bauers, Sage R. [Univ. of Oregon, Eugene, OR (United States); Falmbigl, Matthias [Univ. of Oregon, Eugene, OR (United States); Johnson, David C. [Univ. of Oregon, Eugene, OR (United States)

    2015-04-01T23:59:59.000Z

    A basic summary of thermoelectric principles is presented in a historical context, following the evolution of the field from initial discovery to modern day high-zT materials. A specific focus is placed on nanocomposite materials as a means to solve the challenges presented by the contradictory material requirements necessary for efficient thermal energy harvest. Misfit layer compounds are highlighted as an example of a highly ordered anisotropic nanocomposite system. Their layered structure provides the opportunity to use multiple constituents for improved thermoelectric performance, through both enhanced phonon scattering at interfaces and through electronic interactions between the constituents. Recently, a class of metastable, turbostratically-disordered misfit layer compounds has been synthesized using a kinetically controlled approach with low reaction temperatures. The kinetically stabilized structures can be prepared with a variety of constituent ratios and layering schemes, providing an avenue to systematically understand structure-function relationships not possible in the thermodynamic compounds. We summarize the work that has been done to date on these materials. The observed turbostratic disorder has been shown to result in extremely low cross plane thermal conductivity and in plane thermal conductivities that are also very small, suggesting the structural motif could be attractive as thermoelectric materials if the power factor could be improved. The first 10 compounds in the [(PbSe)1+?]m(TiSe?)n family (m, n ? 3) are reported as a case study. As n increases, the magnitude of the Seebeck coefficient is significantly increased without a simultaneous decrease in the in-plane electrical conductivity, resulting in an improved thermoelectric power factor.

  7. Misfit layer compounds and ferecrystals: Model systems for thermoelectric nanocomposites

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Merrill, Devin R.; Moore, Daniel B.; Bauers, Sage R.; Falmbigl, Matthias; Johnson, David C.

    2015-04-01T23:59:59.000Z

    A basic summary of thermoelectric principles is presented in a historical context, following the evolution of the field from initial discovery to modern day high-zT materials. A specific focus is placed on nanocomposite materials as a means to solve the challenges presented by the contradictory material requirements necessary for efficient thermal energy harvest. Misfit layer compounds are highlighted as an example of a highly ordered anisotropic nanocomposite system. Their layered structure provides the opportunity to use multiple constituents for improved thermoelectric performance, through both enhanced phonon scattering at interfaces and through electronic interactions between the constituents. Recently, a class ofmore »metastable, turbostratically-disordered misfit layer compounds has been synthesized using a kinetically controlled approach with low reaction temperatures. The kinetically stabilized structures can be prepared with a variety of constituent ratios and layering schemes, providing an avenue to systematically understand structure-function relationships not possible in the thermodynamic compounds. We summarize the work that has been done to date on these materials. The observed turbostratic disorder has been shown to result in extremely low cross plane thermal conductivity and in plane thermal conductivities that are also very small, suggesting the structural motif could be attractive as thermoelectric materials if the power factor could be improved. The first 10 compounds in the [(PbSe)1+?]m(TiSe?)n family (m, n ? 3) are reported as a case study. As n increases, the magnitude of the Seebeck coefficient is significantly increased without a simultaneous decrease in the in-plane electrical conductivity, resulting in an improved thermoelectric power factor.« less

  8. Nanostructured Thermoelectric Materials: From Superlattices to Nanocomposites Ronggui Yang1

    E-Print Network [OSTI]

    Chen, Gang

    Nanostructured Thermoelectric Materials: From Superlattices to Nanocomposites Ronggui Yang1 conductivity led to a large increase in the thermoelectric figure of merit in several superlattice systems. Materials with a large thermoelectric figure of merit can be used to develop efficient solid-state devices

  9. Thermal conductivity of self-assembled nano-structured ZnO bulk ceramics

    SciTech Connect (OSTI)

    Zhao, Yu [Bio-Inspired Materials and Devices Laboraory (BMDL); Yan, Yongke [Bio-Inspired Materials and Devices Laboraory (BMDL); Kumar, Ashok [Bio-Inspired Materials and Devices Laboraory (BMDL); Wang, Hsin [ORNL; Porter, Wallace D [ORNL

    2012-01-01T23:59:59.000Z

    In this study, we describe the changes in thermal conductivity behavior of ZnO-Al micro- and nano-two-phase self-assembled composites with varying grain sizes. The reduction in thermal conductivity values of micro-composites was limited to {approx}15% for ZnO-4% Al. However, nano-composites exhibited large reduction, by a factor of about three, due to uniform distribution of nano-precipitates (ZnAl2O4) and large grain boundary area. Interestingly, the micro-composites revealed continuous decrease in thermal conductivity with increase in Al substitution while the nano-composites exhibited the lowest magnitudes for 2% Al concentration. Raman spectra indicated that phonon confinement in ZnO-Al nano-composites causes drastic decrease in the value of thermal conductivity.

  10. Thermal conductivity studies of metal dispersed multiwalled carbon nanotubes in water and ethylene glycol based nanofluids

    SciTech Connect (OSTI)

    Jha, Neetu; Ramaprabhu, S. [Department of Physics, Alternative Energy and Nanotechnology Laboratory (AENL), Nano Functional Materials Technology Centre (NFMTC), Indian Institute of Technology Madras, Chennai 600036 (India)

    2009-10-15T23:59:59.000Z

    High thermal conducting metal nanoparticles have been dispersed on the multiwalled carbon nanotubes (MWNTs) outer surface. Structural and morphological characterizations of metal dispersed MWNTs have been carried out using x-ray diffraction analysis, high resolution transmission electron microscopy, energy dispersive x-ray analysis, and Fourier transform infrared spectroscopy. Nanofluids have been synthesized using metal-MWNTs in de-ionized water (DI water) and ethylene glycol (EG) base fluids. It has been observed that nanofluids maintain the same sequence of thermal conductivity as that of metal nanoparticles Ag-MWNTs>Au-MWNTs>Pd-MWNTs. A maximum enhancement of 37.3% and 11.3% in thermal conductivity has been obtained in Ag-MWNTs nanofluid with DI water and EG as base fluids, respectively, at a volume fraction of 0.03%. Temperature dependence study also shows enhancement of thermal conductivity with temperature.

  11. Effective thermal conductivity measurements relevant to deep borehole nuclear waste disposal

    E-Print Network [OSTI]

    Shaikh, Samina

    2007-01-01T23:59:59.000Z

    The objective of this work was to measure the effective thermal conductivity of a number of materials (particle beds, and fluids) proposed for use in and around canisters for disposal of high level nuclear waste in deep ...

  12. Geometry and temperature dependent thermal conductivity of diamond nanowires: A non-equilibrium molecular dynamics study

    E-Print Network [OSTI]

    Melnik, Roderick

    plasma etching of polycrystalline diamond films [7], microwave plasma assisted chemical vapor deposition. For theoretical calculations of proper- ties of nanosized diamond materials, polycrystalline diamond thin filmsGeometry and temperature dependent thermal conductivity of diamond nanowires: A non

  13. Analysis of the Temporal Evolution of Thermal Conductivity in Alumina-Water Nanofluid 

    E-Print Network [OSTI]

    Fortenberry, Stephen

    2009-09-30T23:59:59.000Z

    In this effort, the temporal behavior of a manufactured alumina (Al2O3) – water nanofluid was evaluated. Measurements of nanofluid effective thermal conductivity were acquired over an extended time period. Analysis of acquired measurements...

  14. Thermal and electrical conduction in the compaction direction of exfoliated graphite

    E-Print Network [OSTI]

    Chung, Deborah D.L.

    Thermal and electrical conduction in the compaction direction of exfoliated graphite in the compaction direction of graphite-flake-based exfoliated graphite have been decoupled. The compact Exfoliated graphite is elongated graphite particles obtained by the exfoliation (typically involving rapid

  15. LARGE SCALE PERMEABILITY TEST OF THE GRANITE IN THE STRIPA MINE AND THERMAL CONDUCTIVITY TEST

    E-Print Network [OSTI]

    Lundstrom, L.

    2011-01-01T23:59:59.000Z

    No.2 LARGE SCALE PERMEABILITY TEST OF THE GRANITE' IN THEMINE AND, THERMAL CONDUCTIVITY TEST Lars Lundstrom and HakanSUMMARY REPORT Background TEST SITE Layout of test places

  16. Mixed ionic and electronic conducting electrode studies for an alkali metal thermal to electric converter

    E-Print Network [OSTI]

    Guo, Yuyan

    2009-05-15T23:59:59.000Z

    This research focuses on preparation, kinetics, and performance studies of mixed ionic and electronic conducting electrodes (MIEE) applied in an alkali metal thermal to electric converter (AMTEC). Two types of MIEE, metal/sodium titanate and metal...

  17. Thermal conductivity of fluids containing suspension of nanometer-sized particles

    E-Print Network [OSTI]

    Ma, Jack Jeinhao

    2006-01-01T23:59:59.000Z

    Nanofluids, which are fluids containing suspension of nanometer-sized particles, have been reported to possess substantially higher thermal conductivity than their respective base fluids. This thesis reports on an experimental ...

  18. Enhancing thermal conductivity of fluids with graphite nanoparticles and carbon nanotube

    DOE Patents [OSTI]

    Zhang, Zhiqiang (Lexington, KY); Lockwood, Frances E. (Georgetown, KY)

    2008-03-25T23:59:59.000Z

    A fluid media such as oil or water, and a selected effective amount of carbon nanomaterials necessary to enhance the thermal conductivity of the fluid. One of the preferred carbon nanomaterials is a high thermal conductivity graphite, exceeding that of the neat fluid to be dispersed therein in thermal conductivity, and ground, milled, or naturally prepared with mean particle size less than 500 nm, and preferably less than 200 nm, and most preferably less than 100 nm. The graphite is dispersed in the fluid by one or more of various methods, including ultrasonication, milling, and chemical dispersion. Carbon nanotubes with graphitic structure is another preferred source of carbon nanomaterial, although other carbon nanomaterials are acceptable. To confer long term stability, the use of one or more chemical dispersants is preferred. The thermal conductivity enhancement, compared to the fluid without carbon nanomaterial, is proportional to the amount of carbon nanomaterials (carbon nanotubes and/or graphite) added.

  19. Lattice thermal conductivity of UO{sub 2} using ab-initio and classical molecular dynamics

    SciTech Connect (OSTI)

    Kim, Hyoungchul [Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); High-Temperature Energy Materials Research Center, Korea Institute of Science and Technology, Seoul 136–791 (Korea, Republic of); Kim, Moo Hwan [Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of); Kaviany, Massoud, E-mail: kaviany@umich.edu [Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109 (United States); Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang 790-784 (Korea, Republic of)

    2014-03-28T23:59:59.000Z

    We applied the non-equilibrium ab-initio molecular dynamics and predict the lattice thermal conductivity of the pristine uranium dioxide for up to 2000?K. We also use the equilibrium classical molecular dynamics and heat-current autocorrelation decay theory to decompose the lattice thermal conductivity into acoustic and optical components. The predicted optical phonon transport is temperature independent and small, while the acoustic component follows the Slack relation and is in good agreement with the limited single-crystal experimental results. Considering the phonon grain-boundary and pore scatterings, the effective lattice thermal conductivity is reduced, and we show it is in general agreement with the sintered-powder experimental results. The charge and photon thermal conductivities are also addressed, and we find small roles for electron, surface polaron, and photon in the defect-free structures and for temperatures below 1500?K.

  20. Basal-plane thermal conductivity of few-layer molybdenum disulfide

    SciTech Connect (OSTI)

    Jo, Insun; Ou, Eric; Shi, Li, E-mail: lishi@mail.utexas.edu [Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); Pettes, Michael Thompson [Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas 78712 (United States); Department of Mechanical Engineering and the Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States); Wu, Wei [Department of Mechanical Engineering and the Institute of Materials Science, University of Connecticut, Storrs, Connecticut 06269 (United States)

    2014-05-19T23:59:59.000Z

    We report the in-plane thermal conductivity of suspended exfoliated few-layer molybdenum disulfide (MoS{sub 2}) samples that were measured by suspended micro-devices with integrated resistance thermometers. The obtained room-temperature thermal conductivity values are (44–50) and (48–52) W m{sup ?1} K{sup ?1} for two samples that are 4 and 7 layers thick, respectively. For both samples, the peak thermal conductivity occurs at a temperature close to 120?K, above which the thermal conductivity is dominated by intrinsic phonon-phonon scattering although phonon scattering by surface disorders can still play an important role in these samples especially at low temperatures.

  1. Temperature dependent thermal conductivity increase of aqueous nanofluid with single walled carbon nanotube inclusions

    E-Print Network [OSTI]

    Maruyama, Shigeo

    1 Temperature dependent thermal conductivity increase of aqueous nanofluid with single walled nanofluids, which we then thoroughly characterized by microscopic and spectroscopic methods. Electrical of the nanofluid was also found to increase with increasing temperature. Viscosity of the nanofluids showed

  2. Analysis of the Temporal Evolution of Thermal Conductivity in Alumina-Water Nanofluid

    E-Print Network [OSTI]

    Fortenberry, Stephen

    2009-09-30T23:59:59.000Z

    In this effort, the temporal behavior of a manufactured alumina (Al2O3) – water nanofluid was evaluated. Measurements of nanofluid effective thermal conductivity were acquired over an extended time period. Analysis of acquired measurements...

  3. DEVELOPMENT OF AN IN-PILE TECHNIQUE FOR THERMAL CONDUCTIVITY MEASUREMENT

    SciTech Connect (OSTI)

    Brandon Fox; Heng Ban; Joy L. Rempe; Joshua E. Daw; Keith G. Condie; Darrell L. Knudson

    2009-04-01T23:59:59.000Z

    Thermophysical properties of advanced fuels and materials during irradiation must be known prior to their use in existing, advanced, or next generation reactors. Fuel thermal conductivity is one of the most important properties for predicting fuel performance and reactor safety. This paper discusses a joint Utah State University (USU)/Idaho National Laboratory (INL) project to investigate an in-pile fuel thermal conductivity measurement technique using a surrogate fuel rod. The method used a surrogate fuel rod with Joule heating to simulate volumetric heat generation as a proof-of-concept test in-pile application. Carbon structural foam, CFOAM®, a product of Touchtone Research Laboratory was chosen as the surrogate material because of the variable electrical and thermal properties upon fabrication. To stay within the surrogate fuel rod requirements, electrical and thermal properties were tailored by Touchtone Research Laboratory to match required values. This paper describes are the techniques used for quantifying thermal conductivity. A description of the test setup and preliminary results are presented. Two thermocouples are inserted into a 1-inch diameter, 6-inch long rod of CFOAM® at known locations. Knowing the applied volumetric heat to the rod by electrical resistance heating, the thermal conductivity can be calculated. Sensitivities of this measurement can also found by analysis and testing of different configurations of the sample setup. Verification of thermal conductivity is found by measuring the thermal properties of the CFOAM® using different methods. Thermal properties including thermal conductivity, specific heat capacity, and expansion coefficient of two types of CFOAM®, CFOAM20 and CFOAM25, were characterized using standard measurement techniques, such as laser flash, differential scanning calorimetry, and pushrod dilatometry.

  4. Thermal contact conductance of metallic coated superconductor/copper interfaces at cryogenic temperatures

    E-Print Network [OSTI]

    Ochterbeck, Jay Matthew

    1990-01-01T23:59:59.000Z

    THERMAL CONTACT CONDUCTANCE OF METALLIC COATED SUPERCONDUCTOR/COPPER INTERFACES AT CRYOGENIC TEMPERATURES A Thesis by JAY MATTHEW OCHTERBECK Submitted to the 0%ce of Graduate Studies of Texas AJrM IJniversity in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE August 1990 Major Subject: Mechanical Engineering THERMAL CONTACT CONDUCTANCE OF METALLIC COATED SUPERCONDUCTOR/COPPER INTERFACES AT CRYOGENIC TEMPERATURES A Thesis JA'r '(IATTHEW OCHTERBECK Approved...

  5. Thermal contact conductance of metallic coated superconductor/copper interfaces at cryogenic temperatures 

    E-Print Network [OSTI]

    Ochterbeck, Jay Matthew

    1990-01-01T23:59:59.000Z

    THERMAL CONTACT CONDUCTANCE OF METALLIC COATED SUPERCONDUCTOR/COPPER INTERFACES AT CRYOGENIC TEMPERATURES A Thesis by JAY MATTHEW OCHTERBECK Submitted to the 0%ce of Graduate Studies of Texas AJrM IJniversity in partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE August 1990 Major Subject: Mechanical Engineering THERMAL CONTACT CONDUCTANCE OF METALLIC COATED SUPERCONDUCTOR/COPPER INTERFACES AT CRYOGENIC TEMPERATURES A Thesis JA'r '(IATTHEW OCHTERBECK Approved...

  6. Thermal Conductivity in Nanoporous Gold Films during Electron-Phonon Nonequilibrium

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Hopkins, Patrick E.; Norris, Pamela M.; Phinney, Leslie M.; Policastro, Steven A.; Kelly, Robert G.

    2008-01-01T23:59:59.000Z

    The reduction of nanodevices has given recent attention to nanoporous materials due to their structure and geometry. However, the thermophysical properties of these materials are relatively unknown. In this article, an expression for thermal conductivity of nanoporous structures is derived based on the assumption that the finite size of the ligaments leads to electron-ligament wall scattering. This expression is then used to analyze the thermal conductivity of nanoporous structures in the event of electron-phonon nonequilibrium.

  7. An experimental measurement of the thermal conductivity and diffusivity of a porous solid-liquid system 

    E-Print Network [OSTI]

    Dunn, James Elliott

    1959-01-01T23:59:59.000Z

    AN EXPERIMENTAL MEASUREMENT QF THE THERMAL CONDUCTIVITY AND DIFFUSIVITY OF A POROUS SOLID LIQUID SYSTEM By James Elliott Dunn A Thesis Submitted to the Graduate School of the Agricultural and Mechanical College of Texas in partial... fulfillment of the reQuirements for the degree of MASTER OF SCIENCE August 1959 Major Sub)ect: Mechanical Engineering AN EXPERIMENTAL MEASURFJ1ENT OF THE THERMAL CONDUCTIVITY AND DIFFUSIVITY OF A POROUS SOLID LIQUID SYSTEM A Thesis James Elliott Dunn...

  8. Propagation of three--dimensional Alfv'en waves in a stratified, thermally conducting solar wind

    E-Print Network [OSTI]

    Propagation of three--dimensional Alfv'en waves in a stratified, thermally conducting solar wind S to the well--known thermal expansion of the solar corona [Parker, 1958, 1963, 1991]. In particular Alfv'en waves in the solar atmosphere and wind, taking into account relevant physical effects

  9. Influence of Chemisorption on the Thermal Conductivity of Single-Wall

    E-Print Network [OSTI]

    Brenner, Donald W.

    composites. However, direct ex- perimental measurements of the thermal properties of CNT- polymer composites to a polymer matrix greatly improves the system's thermal conductivity,8,9 while others report that the effect transfer in CNT-polymer composites without significantly sacrificing the high axial Young's modulus of CNTs

  10. Thermoelectric transport through strongly correlated quantum dots

    E-Print Network [OSTI]

    Costi, T A; 10.1103/PhysRevB.81.235127

    2010-01-01T23:59:59.000Z

    The thermoelectric properties of strongly correlated quantum dots, described by a single level Anderson model coupled to conduction electron leads, is investigated using Wilson's numerical renormalization group method. We calculate the electronic contribution, $K_{\\rm e}$, to the thermal conductance, the thermopower, $S$, and the electrical conductance, $G$, of a quantum dot as a function of both temperature, $T$, and gate voltage, ${\\rm v}_g$, for strong, intermediate and weak Coulomb correlations, $U$, on the dot. For strong correlations and in the Kondo regime, we find that the thermopower exhibits two sign changes, at temperatures $T_{1}({\\rm v}_g)$ and $T_{2}({\\rm v}_g)$ with $T_{1}law in ...

  11. New materials and devices for thermoelectric applications

    SciTech Connect (OSTI)

    Fleurial, J.P.; Borshchevsky, A.; Caillat, T.; Ewell, R. [California Inst. of Tech., Pasadena, CA (United States). Jet Propulsion Lab.

    1997-12-31T23:59:59.000Z

    The development of new, more efficient materials and devices is the key to expanding the range of application of thermoelectric generators and coolers. In the last couple of years, efforts to discover breakthrough thermoelectric materials have intensified, in particular in the US. Recent results on novel materials have already demonstrated that dimensionless figure of merit ZT values 40 to 50% larger than 1.0, the current limit, could be obtained in the 475 to 950 K temperature range. New terrestrial power generation applications have been recently described in the literature. There exists a wide range of heat source temperatures for these applications, from low grade waste heat, at 325--350 K, up to 850 to 1,100 K, such as in the heat recovery from a processing plant of combustible solid waste. The automobile industry has also recently developed a strong interest in a waste exhaust heat recovery power source operating in the 375--750 K temperature range to supplement or replace the alternator and thus decrease fuel consumption. Based on results achieved to date at the Jet Propulsion Laboratory (JPL) on novel materials, the performance of an advanced segmented generator design operating in a large 300--945 K temperature gradient is predicted to achieve about 15% conversion efficiency. This would be a very substantial improvement over state-of-the-art (SOA) thermoelectric power converters. Such a terrestrial power generator could be using waste heat or liquid fuels as a heat source. High performance radioisotope generators (RTG) are still of interest for deep space missions but the shift towards small, light spacecraft has developed a need for advanced power sources in the watt to milliwatt range. The powerstick concept would provide a study, compact, lightweight and low cost answer to this need. The development of thin film thermoelectric devices also offer attractive possibilities. The combination of semiconductor technology, thermoelectric films and high thermal conductivity materials could lead to the fabrication of light weight, high voltage devices with high cooling or high electrical power density characteristics. The use of microcoolers for the thermal management of power electronics is of particular interest.

  12. Photoacoustic measurement of bandgaps of thermoelectric materials

    E-Print Network [OSTI]

    Ni, George (George Wei)

    2014-01-01T23:59:59.000Z

    Thermoelectric materials are a promising class of direct energy conversion materials, usually consisting of highly doped semiconductors. The key to maximizing their thermal to electrical energy conversion lies in optimizing ...

  13. Theoretical efficiency of solar thermoelectric energy generators

    E-Print Network [OSTI]

    Chen, Gang

    This paper investigates the theoretical efficiency of solar thermoelectric generators (STEGs). A model is established including thermal concentration in addition to optical concentration. Based on the model, the maximum ...

  14. Modeling of concentrating solar thermoelectric generators

    E-Print Network [OSTI]

    Ren, Zhifeng

    The conversion of solar power into electricity is dominated by non-concentrating photovoltaics and concentrating solar thermal systems. Recently, it has been shown that solar thermoelectric generators (STEGs) are a viable ...

  15. Effects of neutron irradiation on thermal conductivity of SiC-based composites and monolithic ceramics

    SciTech Connect (OSTI)

    Senor, D.J.; Youngblood, G.E. [Pacific Northwest National Lab., Richland, WA (United States); Moore, C.E. [Auburn Univ., AL (United States); Trimble, D.J. [Westinghouse Hanford Co., Richland, WA (United States); Woods, J.J. [Lockheed Martin, Schenectady, NY (United States)

    1996-06-01T23:59:59.000Z

    A variety of SiC-based composites and monolithic ceramics were characterized by measuring their thermal diffusivity in the unirradiated, thermal annealed, and irradiated conditions over the temperature range 400 to 1,000 C. The irradiation was conducted in the EBR-II to doses of 33 and 43 dpa-SiC (185 EFPD) at a nominal temperature of 1,000 C. The annealed specimens were held at 1,010 C for 165 days to approximately duplicate the thermal exposure of the irradiated specimens. Thermal diffusivity was measured using the laser flash method, and was converted to thermal conductivity using density data and calculated specific heat values. Exposure to the 165 day anneal did not appreciably degrade the conductivity of the monolithic or particulate-reinforced composites, but the conductivity of the fiber-reinforced composites was slightly degraded. The crystalline SiC-based materials tested in this study exhibited thermal conductivity degradation of irradiation, presumably caused by the presence of irradiation-induced defects. Irradiation-induced conductivity degradation was greater at lower temperatures, and was typically more pronounced for materials with higher unirradiated conductivity. Annealing the irradiated specimens for one hour at 150 C above the irradiation temperature produced an increase in thermal conductivity, which is likely the result of interstitial-vacancy pair recombination. Multiple post-irradiation anneals on CVD {beta}-SiC indicated that a portion of the irradiation-induced damage was permanent. A possible explanation for this phenomenon was the formation of stable dislocation loops at the high irradiation temperature and/or high dose that prevented subsequent interstitial/vacancy recombination.

  16. Effects of neutron irradiation on thermal conductivity of SiC-based composites and monolithic ceramics

    SciTech Connect (OSTI)

    Senor, D.J.; Youngblood, G.E. [Pacific Northwest National Lab., Richland, WA (United States); Moore, C.E. [Auburn Univ., AL (United States); Trimble, D.J. [Westinghouse Hanford Co., Richland, WA (United States); Woods, J.J. [Lockheed Martin, Schenectady, NY (United States)

    1997-05-01T23:59:59.000Z

    A variety of SiC-based composites and monolithic ceramics were characterized by measuring their thermal diffusivity in the unirradiated, thermal annealed, and irradiated conditions over the temperature range 400 to 1,000 C. The irradiation was conducted in the EBR-II to doses of 33 and 43 dpa-SiC (185 EFPD) at a nominal temperature of 1,000 C. The annealed specimens were held at 1,010 C for 165 days to approximately duplicate the thermal exposure of the irradiated specimens. Thermal diffusivity was measured using the laser flash method, and was converted to thermal conductivity using density data and calculated specific heat values. Exposure to the 165 day anneal did not appreciably degrade the conductivity of the monolithic or particulate-reinforced composites, but the conductivity of the fiber-reinforced composites was slightly degraded. The crystalline SiC-based materials tested in this study exhibited thermal conductivity degradation after irradiation, presumably caused by the presence of irradiation-induced defects. Irradiation-induced conductivity degradation was greater at lower temperatures, and was typically more pronounced for materials with higher unirradiated conductivity. Annealing the irradiated specimens for one hour at 150 C above the irradiation temperature produced an increase in thermal conductivity, which is likely the result of interstitial-vacancy pair recombination. Multiple post-irradiation anneals on CVD {beta}-SiC indicated that a portion of the irradiation-induced damage was permanent. A possible explanation for this phenomenon was the formation of stable dislocation loops at the high irradiation temperature and/or high dose that prevented subsequent interstitial/vacancy recombination.

  17. EFFECTIVE THERMAL CONDUCTIVITY OF LITHIUM CERAMIC PEBBLE BEDS FOR FUSION BLANKETS: A REVIEW

    E-Print Network [OSTI]

    Abdou, Mohamed

    a significant interest as solid breeders for the fusion blankets during the last three decades. The solid for the fusion solid breeder blankets. In order to study the heat transfer in the blanket, effective conductivityEFFECTIVE THERMAL CONDUCTIVITY OF LITHIUM CERAMIC PEBBLE BEDS FOR FUSION BLANKETS: A REVIEW A. ABOU

  18. Enhanced thermal conductivity and viscosity of copper nanoparticles in ethylene glycol nanofluid

    E-Print Network [OSTI]

    Enhanced thermal conductivity and viscosity of copper nanoparticles in ethylene glycol nanofluid J conductivity and viscosity of copper nanoparticles in ethylene glycol. The nanofluid was prepared calculations suggest that this nanofluid would not be beneficial as a coolant in heat exchangers without

  19. Computational Analysis of Factors Influencing Enhancement of Thermal Conductivity of Nanofluids

    E-Print Network [OSTI]

    Okeke, George; Antony, Joseph; Ding, Yulong; 10.1007/s11051-011-0389-9

    2012-01-01T23:59:59.000Z

    Numerical investigations are conducted to study the effect of factors such as particle clustering and interfacial layer thickness on thermal conductivity of nanofluids. Based on this, parameters including Kapitza radius, and fractal and chemical dimension which have received little attention by previous research are rigorously investigated. The degree of thermal enhancement is analysed for increasing aggregate size, particle concentration, interfacial thermal resistance, and fractal and chemical dimensions. This analysis is conducted for water-based nanofluids of Alumina (Al2O3), CuO and Titania (TiO2) nanoparticles where the particle concentrations are varied up to 4vol%. Results from the numerical work are validated using available experimental data. For the case of aggregate size, particle concentration and interfacial thermal resistance; the aspect ratio (ratio of radius of gyration of aggregate to radius of primary particle, Rg/a) is varied between 2 to 60. It was found that the enhancement decreases wit...

  20. Regulation of thermal conductivity in hot galaxy clusters by MHD turbulence

    E-Print Network [OSTI]

    Steven A. Balbus; Christopher S. Reynolds

    2008-06-05T23:59:59.000Z

    The role of thermal conduction in regulating the thermal behavior of cooling flows in galaxy clusters is reexamined. Recent investigations have shown that the anisotropic Coulomb heat flux caused by a magnetic field in a dilute plasma drives a dynamical instability. A long standing problem of cooling flow theory has been to understand how thermal conduction can offset radiative core losses without completely preventing them. In this Letter we propose that magnetohydrodynamic turbulence driven by the heat flux instability regulates field-line insulation and drives a reverse convective thermal flux, both of which may mediate the stabilization of the cooling cores of hot clusters. This model suggests that turbulent mixing should accompany strong thermal gradients in cooling flows. This prediction seems to be supported by the spatial distribution of metals in the central galaxies of clusters, which shows a much stronger correlation with the ambient hot gas temperature gradient than with the parent stellar population.

  1. Thermoelectric effect in molecular electronics

    E-Print Network [OSTI]

    M. Paulsson; S. Datta

    2003-01-14T23:59:59.000Z

    We provide a theoretical estimate of the thermoelectric current and voltage over a Phenyldithiol molecule. We also show that the thermoelectric voltage is (1) easy to analyze, (2) insensitive to the detailed coupling to the contacts, (3) large enough to be measured and (4) give valuable information, which is not readily accessible through other experiments, on the location of the Fermi energy relative to the molecular levels. The location of the Fermi-energy is poorly understood and controversial even though it is a central factor in determining the nature of conduction (n- or p-type). We also note that the thermoelectric voltage measured over Guanine molecules with an STM by Poler et al., indicate conduction through the HOMO level, i.e., p-type conduction.

  2. Nanoscale size dependence parameters on lattice thermal conductivity of Wurtzite GaN nanowires

    SciTech Connect (OSTI)

    Mamand, S.M., E-mail: soran.mamand@univsul.net [Department of Physics, College of Science, University of Sulaimani, Sulaimanyah, Iraqi Kurdistan (Iraq); Omar, M.S. [Department of Physics, College of Science, University of Salahaddin, Arbil, Iraqi Kurdistan (Iraq)] [Department of Physics, College of Science, University of Salahaddin, Arbil, Iraqi Kurdistan (Iraq); Muhammad, A.J. [Department of Physics, College of Science, University of Kirkuk, Kirkuk (Iraq)] [Department of Physics, College of Science, University of Kirkuk, Kirkuk (Iraq)

    2012-05-15T23:59:59.000Z

    Graphical abstract: Temperature dependence of calculated lattice thermal conductivity of Wurtzite GaN nanowires. Highlights: Black-Right-Pointing-Pointer A modified Callaway model is used to calculate lattice thermal conductivity of Wurtzite GaN nanowires. Black-Right-Pointing-Pointer A direct method is used to calculate phonon group velocity for these nanowires. Black-Right-Pointing-Pointer 3-Gruneisen parameter, surface roughness, and dislocations are successfully investigated. Black-Right-Pointing-Pointer Dislocation densities are decreases with the decrease of wires diameter. -- Abstract: A detailed calculation of lattice thermal conductivity of freestanding Wurtzite GaN nanowires with diameter ranging from 97 to 160 nm in the temperature range 2-300 K, was performed using a modified Callaway model. Both longitudinal and transverse modes are taken into account explicitly in the model. A method is used to calculate the Debye and phonon group velocities for different nanowire diameters from their related melting points. Effect of Gruneisen parameter, surface roughness, and dislocations as structure dependent parameters are successfully used to correlate the calculated values of lattice thermal conductivity to that of the experimentally measured curves. It was observed that Gruneisen parameter will decrease with decreasing nanowire diameters. Scattering of phonons is assumed to be by nanowire boundaries, imperfections, dislocations, electrons, and other phonons via both normal and Umklapp processes. Phonon confinement and size effects as well as the role of dislocation in limiting thermal conductivity are investigated. At high temperatures and for dislocation densities greater than 10{sup 14} m{sup -2} the lattice thermal conductivity would be limited by dislocation density, but for dislocation densities less than 10{sup 14} m{sup -2}, lattice thermal conductivity would be independent of that.

  3. Effective Thermal Conductivity of Lithium Ceramic Pebble Beds for Fusion Blankets: A Review

    SciTech Connect (OSTI)

    Abou-Sena, A.; Ying, A.; Abdou, M. [University of California, Los Angeles (United States)

    2005-05-15T23:59:59.000Z

    The use of lithium ceramic pebble beds has been considered in many blanket designs for the fusion reactors. Lithium ceramics have received a significant interest as tritium breeders for the fusion blankets during the last three decades. The thermal performance of the lithium ceramic pebble beds plays a key role for the fusion blankets. In order to study the heat transfer in the blanket, the effective thermal conductivity of the lithium ceramics pebble beds has to be well measured and characterized. The data of effective thermal conductivity of lithium ceramic pebble beds is important for the blanket design. Several studies have been dedicated to investigate the effective conductivity of the lithium ceramics pebble beds. The objective of this work is to review and compare the available data, presented by various studies, of effective conductivity of lithium ceramic pebble beds in order to address the current status of these data.

  4. Composite material having high thermal conductivity and process for fabricating same

    DOE Patents [OSTI]

    Colella, N.J.; Davidson, H.L.; Kerns, J.A.; Makowiecki, D.M.

    1998-07-21T23:59:59.000Z

    A process is disclosed for fabricating a composite material such as that having high thermal conductivity and having specific application as a heat sink or heat spreader for high density integrated circuits. The composite material produced by this process has a thermal conductivity between that of diamond and copper, and basically consists of coated diamond particles dispersed in a high conductivity metal, such as copper. The composite material can be fabricated in small or relatively large sizes using inexpensive materials. The process basically consists, for example, of sputter coating diamond powder with several elements, including a carbide forming element and a brazeable material, compacting them into a porous body, and infiltrating the porous body with a suitable braze material, such as copper-silver alloy, thereby producing a dense diamond-copper composite material with a thermal conductivity comparable to synthetic diamond films at a fraction of the cost. 7 figs.

  5. Convection in nanofluids with a particle-concentration-dependent thermal conductivity

    E-Print Network [OSTI]

    Glässl, Martin; Zimmermann, Walter

    2010-01-01T23:59:59.000Z

    Thermal convection in nanofluids is investigated by means of a continuum model for binary-fluid mixtures, with a thermal conductivity depending on the local concentration of colloidal particles. The applied temperature difference between the upper and the lower boundary leads via the Soret effect to a variation of the colloid concentration and therefore to a spatially varying heat conductivity. An increasing difference between the heat conductivity of the mixture near the colder and the warmer boundary results in a shift of the onset of convection to higher values of the Rayleigh number for positive values of the separation ratio $\\psi>0$ and to smaller values in the range $\\psi0$. This range can be extended by increasing the difference in the thermal conductivity and it is bounded by two codimension-2 bifurcations.

  6. Convection in nanofluids with a particle-concentration-dependent thermal conductivity

    E-Print Network [OSTI]

    Martin Glässl; Markus Hilt; Walter Zimmermann

    2011-03-09T23:59:59.000Z

    Thermal convection in nanofluids is investigated by means of a continuum model for binary-fluid mixtures, with a thermal conductivity depending on the local concentration of colloidal particles. The applied temperature difference between the upper and the lower boundary leads via the Soret effect to a variation of the colloid concentration and therefore to a spatially varying heat conductivity. An increasing difference between the heat conductivity of the mixture near the colder and the warmer boundary results in a shift of the onset of convection to higher values of the Rayleigh number for positive values of the separation ratio psi>0 and to smaller values in the range psi0. This range can be extended by increasing the difference in the thermal conductivity and it is bounded by two codimension-2 bifurcations.

  7. High temperature thermoelectrics

    DOE Patents [OSTI]

    Moczygemba, Joshua E.; Biershcenk, James L.; Sharp, Jeffrey W.

    2014-09-23T23:59:59.000Z

    In accordance with one embodiment of the present disclosure, a thermoelectric device includes a plurality of thermoelectric elements that each include a diffusion barrier. The diffusion barrier includes a refractory metal. The thermoelectric device also includes a plurality of conductors coupled to the plurality of thermoelectric elements. The plurality of conductors include aluminum. In addition, the thermoelectric device includes at least one plate coupled to the plurality of thermoelectric elements using a braze. The braze includes aluminum.

  8. Composite Thermal Conductivity in a Large Heterogeneous PorousMethane Hydrate Sample

    SciTech Connect (OSTI)

    Gupta, Arvind; Kneafsey, Timothy J.; Moridis George J.; Seol,Yongkoo; Kowalsky, Michael B.; Sloan Jr., E.D.

    2006-08-01T23:59:59.000Z

    By employing inverse modeling to analyze the laboratorydata, we determined the composite thermal conductivity (k theta W/m/K) ofa porous methane hydrate sample ranged between 0.25 and 0.58 W/m/K as afunction of density. The calculated composite thermal diffusivities ofporous hydrate sample ranged between 2.59x10-7 m2/s and 3.71x10-7 m2/s.The laboratory study involved a large heterogeneous sample (composed ofhydrate, water, and methane gas). The measurements were conductedisobarically at 4.98 MPa over a temperature range of 277.3-279.1 K.Pressure and temperature were monitored at multiple locations in thesample. X-ray computed tomography (CT) was used to visualize and quantifythe density changes that occurred during hydrate formation from granularice. CT images showed that methane hydrate formed from granular ice washeterogeneous and provided an estimate of the sample density variation inthe radial direction. This facilitated quantifying the density effect oncomposite thermal conductivity. This study showed that the sampleheterogeneity should be considered in thermal conductivity measurementsof hydrate systems. Mixing models (i.e., arithmetic, harmonic, geometricmean, and square root models) were compared to the estimated compositethermal conductivity determined by inverse modeling. The results of thearithmetic mean model showed the best agreement with the estimatedcomposite thermal conductivity.

  9. Coherent Thermoelectric Effects in Mesoscopic Andreev Interferometers

    E-Print Network [OSTI]

    Ph. Jacquod; R. S. Whitney

    2009-10-15T23:59:59.000Z

    We investigate thermoelectric transport through Andreev interferometers. We show that the ratio of the thermal and the charge conductance exhibits large oscillations with the phase difference $\\phi$ between the two superconducting contacts, and that the Wiedemann-Franz law holds only when $\\phi=\\pi$. A large average thermopower furthermore emerges whenever there is an asymmetry in the dwell times to reach the superconducting contacts. When this is the case, the thermopower is odd in $\\phi$. In contrast, when the average times to reach either superconducting contact are the same, the average thermopower is zero, however mesoscopic effects (analogous to universal conductance fluctuations) lead to a sample-dependent thermopower which is systematically even in $\\phi$.

  10. Thermal Transport Measurement of Silicon-Germanium Nanowires 

    E-Print Network [OSTI]

    Gwak, Yunki

    2010-10-12T23:59:59.000Z

    Thermal properties of one dimensional nanostructures are of interest for thermoelectric energy conversion. Thermoelectric efficiency is related to non dimensional thermoelectric figure of merit, ZT=S^2 o T/k, where S ,o , k and T are Seebeck...

  11. Thermal Energy Harvesting with Thermoelectrics for Self-powered Sensors: With Applications to Implantable Medical Devices, Body Sensor Networks and Aging in Place

    E-Print Network [OSTI]

    Chen, Alic

    2011-01-01T23:59:59.000Z

    market for MEMS and micro-scale thermoelectric heating andheating and cooling mattress called the YuMe Climate Control Bed, albeit for the luxury mattress market [

  12. Thermal Conductivity and Large Isotope Effect in GaN from First Principles

    SciTech Connect (OSTI)

    Lindsay, L. [Naval Research Lab. (NRL), Washington, DC (United States); Broido, D. A. [Boston College, Chestnut Hill, MA (United States); Reinecke, T. L. [Naval Research Lab. (NRL), Washington, DC (United States)

    2012-08-01T23:59:59.000Z

    We present atomistic first principles results for the lattice thermal conductivity of GaN and compare them to those for GaP, GaAs, and GaSb. In GaN we find a large increase to the thermal conductivity with isotopic enrichment, ~65% at room temperature. We show that both the high thermal conductivity and its enhancement with isotopic enrichment in GaN arise from the weak coupling of heat-carrying acoustic phonons with optic phonons. This weak scattering results from stiff atomic bonds and the large Ga to N mass ratio, which give phonons high frequencies and also a pronounced energy gap between acoustic and optic phonons compared to other materials. Rigorous understanding of these features in GaN gives important insights into the interplay between intrinsic phonon-phonon scattering and isotopic scattering in a range of materials.

  13. Thermal Conductivity and Seebeck Coefficients of Icosahedral Boron Arsenide Films on Silicon Carbide

    SciTech Connect (OSTI)

    Y Gong; Y Zhang; M Dudley; Y Zhang; J Edgar; P Heard; M Kuball

    2011-12-31T23:59:59.000Z

    The thermal conductivity of icosahedral boron arsenide (B{sub 12}As{sub 2}) films grown on (0001) 6H-SiC substrates by chemical vapor deposition was studied by the 3{omega} technique. The room temperature thermal conductivity decreased from 27.0 to 15.3 W/m K as the growth temperature was decreased from 1450 to 1275 C. This is mainly attributed to the differences in the impurity concentration and microstructure, determined from secondary ion mass spectrometry and high resolution transmission electron microscopy, respectively. Callaway's theory was applied to calculate the temperature-dependent thermal conductivity, and the results are in good agreement with the experimental data. Seebeck coefficients were determined as 107 {micro}V/K and 136 {micro}V/K for samples grown at 1350 C with AsH{sub 3}/B{sub 2}H{sub 6} flow ratio equals to 1:1 and 3:5, respectively.

  14. Role of anisotropic thermal conductivity in the reversed-field pinch dynamics

    SciTech Connect (OSTI)

    Onofri, M.; Malara, F.; Veltri, P. [Dipartimento di Fisica, Universita della Calabria, ponte P. Bucci, Cubo 31C, 87036 Rende (Italy)

    2011-05-15T23:59:59.000Z

    Two compressible magnetohydrodynamics simulations of the reversed-field pinch are performed, with isotropic and anisotropic thermal conductivity. We describe in detail the numerical method we use to reproduce the effect of a large parallel thermal conductivity, which makes magnetic field lines almost isothermal. We compare the results of the two simulations, showing that the anisotropic thermal conductivity causes the formation of a hot island when closed magnetic surfaces exist, while temperature becomes almost uniform when the magnetic field is chaotic. After a transient single-helicity state that is formed in the initial phase, a stationary state is reached where the RFP configuration exists in a multiple helicity state, even though the Hartmann number is below the threshold found in previous simulations for the formation of multiple helicity states.

  15. Dispersion stability and thermal conductivity of propylene glycol-based nanofluids

    E-Print Network [OSTI]

    Palabiyik, Ibrahim; Witharana, Sanjeeva; Ding, Yulong; 10.1007/s11051-011-0485-x

    2012-01-01T23:59:59.000Z

    The dispersion stability and thermal conductivity of propylene glycol based nanofluids containing Al2O3 and TiO2 nanoparticles were studied in the temperature range of 20 to 80 {\\deg}C. Nanofluids with different concentrations of nanoparticles were formulated by the two-step method without use of dispersants. In contrast to the common belief the average particle size of nanofluids was observed to decrease with increasing temperature. The nanofluids showed excellent stability over the temperature range of interest. Thermal conductivity enhancement for both of studied nanofluids was a non-linear function of concentration while was temperature independent. Theoretical analyses were performed using existing models and comparisons were made with experimental results. The model based on the aggregation theory appears to yield the best fit. Keywords: Nanofluids, Propylene glycol, Alumina nanoparticles, Titania nanoparticles, Thermal conductivity, Dispersion stability.

  16. Dispersion stability and thermal conductivity of propylene glycol-based nanofluids

    E-Print Network [OSTI]

    Ibrahim Palabiyik; Zenfira Musina; Sanjeeva Witharana; Yulong Ding

    2012-05-09T23:59:59.000Z

    The dispersion stability and thermal conductivity of propylene glycol based nanofluids containing Al2O3 and TiO2 nanoparticles were studied in the temperature range of 20 to 80 {\\deg}C. Nanofluids with different concentrations of nanoparticles were formulated by the two-step method without use of dispersants. In contrast to the common belief the average particle size of nanofluids was observed to decrease with increasing temperature. The nanofluids showed excellent stability over the temperature range of interest. Thermal conductivity enhancement for both of studied nanofluids was a non-linear function of concentration while was temperature independent. Theoretical analyses were performed using existing models and comparisons were made with experimental results. The model based on the aggregation theory appears to yield the best fit. Keywords: Nanofluids, Propylene glycol, Alumina nanoparticles, Titania nanoparticles, Thermal conductivity, Dispersion stability.

  17. NSF/DOE Thermoelectric Partnership: High-Performance Thermoelectric...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    High-Performance Thermoelectric Devices Based on Abundant Silicide Materials for Vehicle Waste Heat Recovery NSFDOE Thermoelectric Partnership: High-Performance Thermoelectric...

  18. Pump-probe measurements of the thermal conductivity tensor for materials lacking in-plane symmetry

    SciTech Connect (OSTI)

    Feser, Joseph P. [Department of Mechanical Engineering, University of Delaware, Newark, Delaware 19716 (United States); Liu, Jun; Cahill, David G. [Department of Materials Science and Engineering, and Frederick-Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801 (United States)

    2014-10-15T23:59:59.000Z

    We previously demonstrated an extension of time-domain thermoreflectance (TDTR) which utilizes offset pump and probe laser locations to measure in-plane thermal transport properties of multilayers. However, the technique was limited to systems of transversely isotropic materials studied using axisymmetric laser intensities. Here, we extend the mathematics so that data reduction can be performed on non-transversely isotropic systems. An analytic solution of the diffusion equation for an N-layer system is given, where each layer has a homogenous but otherwise arbitrary thermal conductivity tensor and the illuminating spots have arbitrary intensity profiles. As a demonstration, we use both TDTR and time-resolved magneto-optic Kerr effect measurements to obtain thermal conductivity tensor elements of <110> ?-SiO{sub 2}. We show that the out-of-phase beam offset sweep has full-width half-maxima that contains nearly independent sensitivity to the in-plane thermal conductivity corresponding to the scanning direction. Also, we demonstrate a Nb-V alloy as a low thermal conductivity TDTR transducer layer that helps improve the accuracy of in-plane measurements.

  19. Computational Analysis of Factors Influencing Enhancement of Thermal Conductivity of Nanofluids

    E-Print Network [OSTI]

    George Okeke; Sanjeeva Witharana; Joseph Antony; Yulong Ding

    2012-05-09T23:59:59.000Z

    Numerical investigations are conducted to study the effect of factors such as particle clustering and interfacial layer thickness on thermal conductivity of nanofluids. Based on this, parameters including Kapitza radius, and fractal and chemical dimension which have received little attention by previous research are rigorously investigated. The degree of thermal enhancement is analysed for increasing aggregate size, particle concentration, interfacial thermal resistance, and fractal and chemical dimensions. This analysis is conducted for water-based nanofluids of Alumina (Al2O3), CuO and Titania (TiO2) nanoparticles where the particle concentrations are varied up to 4vol%. Results from the numerical work are validated using available experimental data. For the case of aggregate size, particle concentration and interfacial thermal resistance; the aspect ratio (ratio of radius of gyration of aggregate to radius of primary particle, Rg/a) is varied between 2 to 60. It was found that the enhancement decreases with interfacial layer thickness. Also the rate of decrease is more significant after a given aggregate size. For a given interfacial resistance, the enhancement is mostly sensitive to Rg/a <20 indicated by the steep gradients of data plots. Predicted and experimental data for thermal conductivity enhancement are in good agreement.

  20. Thermal Conductivity of Thermally-Isolating Polymeric and Composite Structural Support Materials Between 0.3 and 4 K

    E-Print Network [OSTI]

    M. C. Runyan; W. C. Jones

    2008-06-11T23:59:59.000Z

    We present measurements of the low-temperature thermal conductivity of a number of polymeric and composite materials from 0.3 to 4 K. The materials measured are Vespel SP-1, Vespel SP-22, unfilled PEEK, 30% carbon fiber-filled PEEK, 30% glass-filled PEEK, carbon fiber Graphlite composite rod, Torlon 4301, G-10/FR-4 fiberglass, pultruded fiberglass composite, Macor ceramic, and graphite rod. These materials have moderate to high elastic moduli making them useful for thermally-isolating structural supports.

  1. An experimental measurement of the thermal conductivity and diffusivity of a porous solid-liquid system

    E-Print Network [OSTI]

    Dunn, James Elliott

    1959-01-01T23:59:59.000Z

    . 6. The Relation of to SE for Values of K Calculated by the Heat Neter K SE Nethod 10 13 15 17 22 7. The Relation of the Thermal Conductivity of Fluid Saturated Sandstone to the Thermal Conductivity of the Saturating Fluid 8. The Variation... of pressures and temperatures and at flow and non-flow states (3)~(6), (7), The advent of widespread interest in increasing petroleum recovery from subterranean reservoirs by applying heat to an oil-bearing for- mation (8), (9), (10) has created a need...

  2. Predicting Thermal Conductivity Evolution of Polycrystalline Materials Under Irradiation Using Multiscale Approach

    SciTech Connect (OSTI)

    Li, Dongsheng; Li, Yulan; Hu, Shenyang Y.; Sun, Xin; Khaleel, Mohammad A.

    2012-03-01T23:59:59.000Z

    A multiscale methodology was developed to predict the evolution of thermal conductivity of polycrystalline fuel under irradiation. In the mesoscale level, phase field model was used to predict the evolution of gas bubble microstructure. Generation of gas atoms and vacancies were taken into consideration. In the macroscopic scale, a statistical continuum mechanics model was applied to predict the anisotropic thermal conductivity evolution during irradiation. Microstructure predicted by phase field model was fed into statistical continuum mechanics model to predict properties and behavior. Influence of irradiation intensity, exposition time and morphology were investigated. This approach provides a deep understanding on microstructure evolution and property prediction from a basic scientific viewpoint.

  3. Estimation of composite thermal conductivity of a heterogeneousmethane hydrate sample using iTOUGH2

    SciTech Connect (OSTI)

    Gupta, Arvind; Kneafsey, Timothy J.; Moridis, George J.; Seol,Yongkoo; Kowalsky, Michael B.; Sloan Jr., E.D.

    2006-05-15T23:59:59.000Z

    We determined the composite thermal conductivity (ktheta) ofa porous methanehydrate sample (composedof hydrate, water, and methan egas) as a function of density using iTOUGH2. X-ray computed tomography(CT) was used to visualize and quantify the density changes that occurredduring hydrate formation from granular ice. The composite thermalconductivity was estimated and validated by minimizing the differencesbetween the observed and the predicted thermal response using historymatching. The estimated density-dependent composite thermal conductivityranged between 0.25 and 0.58 W/m/K.

  4. MESO-SCALE MODELING OF THE INFLUENCE OF INTERGRANULAR GAS BUBBLES ON EFFECTIVE THERMAL CONDUCTIVITY

    SciTech Connect (OSTI)

    Paul C. Millett; Michael Tonks

    2011-06-01T23:59:59.000Z

    Using a mesoscale modeling approach, we have investigated how intergranular fission gas bubbles, as observed in high-burnup nuclear fuel, modify the effective thermal conductivity in a polycrystalline material. The calculations reveal that intergranular porosity has a significantly higher resistance to heat transfer compared to randomly-distributed porosity. A model is developed to describe this conductivity reduction that considers an effective grain boundary Kapitza resistance as a function of the fractional coverage of grain boundaries by bubbles.

  5. Synthesis and transport property of AgSbTe{sub 2} as a promising thermoelectric compound

    SciTech Connect (OSTI)

    Wang Heng; Li Jingfeng; Zou Minmin; Sui Tao [State Key Laboratory of New Ceramics and Fine Processing, Department of Materials Science and Engineering, Tsinghua University, Beijing 100084 (China)

    2008-11-17T23:59:59.000Z

    Polycrystalline AgSbTe{sub 2} ternary compound materials with high phase purity were fabricated using a combined process of mechanical alloying and spark plasma sintering. It was found that stoichiometric AgSbTe{sub 2} is a promising composition for low-and-mediate temperature applications, whose ZT reaches 1.59 at 673 K, benefiting from its extremely low thermal conductivity (0.30 W/mK) in addition to its low electrical resistivity (<1.1x10{sup -4} {omega} m) and large positive Seebeck coefficient (260 {mu}V/K). On the other hand, deviating from this formula would lead to unstable phase structures and higher thermal conductivity, which make the samples less attractive as thermoelectric materials or components of thermoelectric systems.

  6. Concentrated Thermoelectric Power

    Broader source: Energy.gov [DOE]

    This fact sheet describes a concentrated solar hydroelectric power project awarded under the DOE's 2012 SunShot Concentrating Solar Power R&D award program. The team, led by MIT, is working to demonstrate concentrating solar thermoelectric generators with >10% solar-to-electrical energy conversion efficiency while limiting optical concentration to less than a factor of 10 and potentially less than 4. When combined with thermal storage, CSTEGs have the potential to provide electricity day and night using no moving parts at both the utility and distributed scale.

  7. Tuning thermal conductivity of nanoporous crystalline silicon by surface passivation: A molecular dynamics study

    E-Print Network [OSTI]

    Pilon, Laurent

    ) Electron-dependent thermoelectric properties in Si/Si1-xGex heterostructures and Si1-xGex alloys from first dynamics study Jin Fang and Laurent Pilona) Mechanical and Aerospace Engineering Department, Henry Samueli

  8. Isotope Effect on the Thermal Conductivity of Boron Nitride Nanotubes C. W. Chang,1,5

    E-Print Network [OSTI]

    Zettl, Alex

    been achieved in Si and Ge via isotopic enrichment [7,8], with enriched carbon (diamond) showing that an enhancement of due to isotope enrichment could be large in boron nitride nanotubes [20]. Although previousIsotope Effect on the Thermal Conductivity of Boron Nitride Nanotubes C. W. Chang,1,5 A. M

  9. Coupled vibrational modes in multiple-filled skutterudites and the effects on lattice thermal conductivity reduction

    E-Print Network [OSTI]

    Xu, Xianfan

    of studies including Raman spectroscopy,9 inelastic neutron scattering, heat capacity measurements,10, which scatter phonons in different spectral spans. Using a Debye model for the measured lattice thermal conductivity together with the measured vibration frequencies and scattering rates, it is shown that scattering

  10. Enhanced Thermal Conductivity of Water with Surfactant Encapsulated and Individualized Single-Walled Carbon Nanotube Dispersions

    E-Print Network [OSTI]

    Maruyama, Shigeo

    experimentally using a transient hot wire technique at room temperature. Single-walled carbon nanotubes (SWNTs] Maruyama.S, Kojima.R, Miyauchi.Y, Chiashi.S, Kohno.M, Low temperature synthesis of high purity singleEnhanced Thermal Conductivity of Water with Surfactant Encapsulated and Individualized Single

  11. Connection between elastic moduli and thermal conductivities of anisotropic short fiber reinforced thermoplastics: theory and

    E-Print Network [OSTI]

    Sevostianov, Igor

    Elsevier B.V. All rights reserved. Keywords: Polymer matrix composites; Short-fiber composite; ElasticConnection between elastic moduli and thermal conductivities of anisotropic short fiber reinforced form 29 May 2003 Abstract Cross-property connections for two phase composites derived recently

  12. Measurement of the electronic thermal conductance channels and heat capacity of graphene at low temperature

    E-Print Network [OSTI]

    Measurement of the electronic thermal conductance channels and heat capacity of graphene at low, Gwf , test the Wiedemann-Franz (wf) law, and infer the electronic heat capacity, with a minimum value of a Coulomb-interacting electron-hole plasma may result in deviations from the Fermi-liquid values of the Mott

  13. Effect of aggregation on thermal conduction in colloidal nanofluids Ravi Prashera ,b

    E-Print Network [OSTI]

    Fish, Jacob

    Effect of aggregation on thermal conduction in colloidal nanofluids Ravi Prashera ,b Intel of nanofluids can be significantly enhanced by the aggregation of nanoparticles into clusters. Predictions of the effective medium theory are in excellent agreement with detailed numerical calculation on model nanofluids

  14. Tunable electronic properties and low thermal conductivity in synthetic colusites Cu{sub 26?x}Zn{sub x}V{sub 2}M{sub 6}S{sub 32} (x ? 4, M = Ge, Sn)

    SciTech Connect (OSTI)

    Suekuni, K., E-mail: ksuekuni@jaist.ac.jp; Kim, F. S. [Department of Quantum Matter, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8530 (Japan); Takabatake, T. [Department of Quantum Matter, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8530 (Japan); Institute for Advanced Materials Research, Hiroshima University, Higashi-Hiroshima 739-8530 (Japan)

    2014-08-14T23:59:59.000Z

    We have first synthesized Cu{sub 26?x}Zn{sub x}V{sub 2}M{sub 6}S{sub 32} (x???4, M?=?Ge, Sn) with the cubic colusite structure and measured the thermoelectric properties. For both M?=?Ge and Sn, the samples with x?=?0 show moderately large thermopower of +27 ?V/K at 300?K. The metallic conduction of p-type carriers and Pauli-paramagnetic behavior are consistent with the electron-deficient character expected from the formal charge Cu{sub 26}{sup 1+}V{sub 2}{sup 5+}M{sub 6}{sup 4+}S{sub 32}{sup 2?}. The substitution of Zn for Cu results in significant increases in both the electrical resistivity and thermopower. The resistivity of the samples with x?=?4 displays a three-dimensional variable-range hopping behavior at low temperatures. These facts indicate that the doped electrons fill the unoccupied states in the valence band and thereby the Fermi level moves to the localized electronic states at the top of the band. The lattice thermal conductivity is as low as ?1?W/Km at 300?K for all samples. The structural and thermoelectric properties of the colusites are discussed in comparison with those of doped tetrahedrite Cu{sub 12?x}Zn{sub x}Sb{sub 4}S{sub 13}.

  15. Field test of a new method for determining soil formation thermal conductivity and borehole resistance

    SciTech Connect (OSTI)

    Shonder, J.A.; Beck, J.V.

    2000-07-01T23:59:59.000Z

    A new method of determining soil thermal properties from in-situ tests has been developed. Based on a one-dimensional numerical heat transfer model, the method uses parameter estimation techniques to determine soil thermal conductivity and borehole resistance from field-collected data. This paper presents the results of analysis of data from three tests performed in Lincoln, Nebraska, in order to validate the method. The one-dimensional method was found to agree well with line source and cylindrical source thermal conductivity estimates derived from the same data sets. The method was also able to measure the resistance of the three borehole heat exchangers. The measured resistances lie within the expected range of resistances for the given grouting materials. A further benefit of the method is its relative insensitivity to changes in power input caused by short-term voltage fluctuations.

  16. Thermal conductivity of the one-dimensional Fermi-Hubbard model

    E-Print Network [OSTI]

    C. Karrasch; D. M. Kennes; F. Heidrich-Meisner

    2015-06-18T23:59:59.000Z

    We study the thermal conductivity of the one-dimensional Fermi-Hubbard model at finite temperature using a density matrix renormalization group approach. The integrability of this model gives rise to ballistic thermal transport. We calculate the temperature dependence of the thermal Drude weight at half filling for various interactions and moreover, we compute its filling dependence at infinite temperature. The finite-frequency contributions originating from the fact that the energy current is not a conserved quantity are investigated as well. We report evidence that breaking the integrability through a nearest-neighbor interaction leads to vanishing Drude weights and diffusive energy transport. Moreover, we demonstrate that energy spreads ballistically in local quenches with initially inhomogeneous energy density profiles in the integrable case. We discuss the relevance of our results for thermalization in ultra-cold quantum gas experiments and for transport measurements with quasi-one dimensional materials.

  17. Thermoelectric transport through strongly correlated quantum dots

    E-Print Network [OSTI]

    T. A. Costi; V. Zlatic

    2010-07-08T23:59:59.000Z

    The thermoelectric properties of strongly correlated quantum dots, described by a single level Anderson model coupled to conduction electron leads, is investigated using Wilson's numerical renormalization group method. We calculate the electronic contribution, $K_{\\rm e}$, to the thermal conductance, the thermopower, $S$, and the electrical conductance, $G$, of a quantum dot as a function of both temperature, $T$, and gate voltage, ${\\rm v}_g$, for strong, intermediate and weak Coulomb correlations, $U$, on the dot. For strong correlations and in the Kondo regime, we find that the thermopower exhibits two sign changes, at temperatures $T_{1}({\\rm v}_g)$ and $T_{2}({\\rm v}_g)$ with $T_{1}< T_{2}$. Such sign changes in $S(T)$ are particularly sensitive signatures of strong correlations and Kondo physics. The relevance of this to recent thermopower measurements of Kondo correlated quantum dots is discussed. We discuss the figure of merit, power factor and the degree of violation of the Wiedemann-Franz law in quantum dots. The extent of temperature scaling in the thermopower and thermal conductance of quantum dots in the Kondo regime is also assessed.

  18. Thermoelectric Materials, Devices and Systems:

    Broader source: Energy.gov (indexed) [DOE]

    -DRAFT - FOR OFFICIAL USE ONLY - DRAFT Thermoelectric Materials, Devices and Systems: 1 Technology Assessment 2 Contents 3 1. Thermoelectric Generation ......

  19. Combustion Synthesis of Doped Thermoelectric Oxides

    SciTech Connect (OSTI)

    Selig, Jiri [Lamar University; Lin, Sidney [Lamar University; Lin, Hua-Tay [ORNL; Johnson, D Ray [ORNL

    2012-01-01T23:59:59.000Z

    Self-propagating high-temperature synthesis (SHS) was used to prepare silver doped calcium cobaltates (Ca1.24- xAgxCo1.62O3.86, x = 0.03 - 0.12) powders. SHS is a simple and economic process to synthesize ceramic materials with minimum energy requirements. The heat generated by the SHS reaction can sustain the propagation of the reaction front and convert reactants to desired products. The effect of doping level on thermoelectric properties was investigated in this study. Results show the substitution of calcium by silver decreases the thermal conductivity significantly. XRD and surface area measurements show synthesized powders are phase pure and have large specific surface areas.

  20. Polarization field engineering of GaN/AlN/AlGaN superlattices for enhanced thermoelectric properties

    SciTech Connect (OSTI)

    Sztein, Alexander, E-mail: asztein@umail.ucsb.edu [Materials Department, University of California, Santa Barbara, California 93106 (United States); Bowers, John E.; DenBaars, Steven P.; Nakamura, Shuji [Materials Department, University of California, Santa Barbara, California 93106 (United States); Electrical and Computer Engineering Department, University of California, Santa Barbara, California 93106 (United States)

    2014-01-27T23:59:59.000Z

    A novel polarization field engineering based strategy to simultaneously achieve high electrical conductivity and low thermal conductivity in thermoelectric materials is demonstrated. Polarization based electric fields are used to confine electrons into two-dimensional electron gases in GaN/AlN/Al{sub 0.2}Ga{sub 0.8}N superlattices, resulting in improved electron mobilities as high as 1176 cm{sup 2}/Vs and in-plane thermal conductivity as low as 8.9?W/mK. The resulting room temperature ZT values reach 0.08, a factor of four higher than InGaN and twelve higher than GaN, demonstrating the potential benefits of this polarization based engineering strategy for improving the ZT and efficiencies of thermoelectric materials.

  1. Scalable Routes to Efficient Thermoelectric Materials

    E-Print Network [OSTI]

    Feser, Joseph Patrick

    2010-01-01T23:59:59.000Z

    thermoelectric materials consisting of epitaxially-grownefficient thermoelectric materials," Nature, vol. 451, pp.superlattice thermoelectric materials and devices," Science,

  2. Waste Heat Recovery Opportunities for Thermoelectric Generators...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Waste Heat Recovery Opportunities for Thermoelectric Generators Waste Heat Recovery Opportunities for Thermoelectric Generators Thermoelectrics have unique advantages for...

  3. Thermal Conductivity of SiC/Si Composites – Porting PNNL EMTA Code for Fusion Analyses

    SciTech Connect (OSTI)

    Henager, Charles H.; Nguyen, Ba Nghiep

    2013-04-19T23:59:59.000Z

    An existing modeling method, the EMTA (Eshelby-Mori-Tanaka approach) modeling approach [1], is applied to the study of SiC/SiC 2D woven composites for fusion reactor applications for the first time, to the best of our knowledge, with excellent results. We compare EMTA model results to existing thermal conductivity data for these materials and suggest that in the future this approach can be beneficial by providing us with tools to further optimize these composite materials for fusion energy applications since the EMTA method and code can address both thermal and mechanical properties with the same framework.

  4. Thermal and Electric Conductivities of Coulomb Crystals in the Inner Crust of a Neutron Star

    E-Print Network [OSTI]

    D. A. Baiko; D. G. Yakovlev

    1996-04-28T23:59:59.000Z

    Thermal and electric conductivities of relativistic degenerate electrons are calculated for the case when electrons scatter by phonons in Coulomb crystals made of spherical finite--size nuclei at densities $10^{11}$~g/cm$^3 neutron star. In combination with the results of the previous article (for lower $\\rho$), simple unified fits are obtained which describe the kinetic coefficients in the range $10^3$~g/cm$^3 neutron stars and evolution of their magnetic fields. The difference between the kinetic coefficients in the neutron star crust composed of ground state and accreted matters is analyzed. Thermal drift of the magnetic field in the neutron star crust is discussed.

  5. Thermal conductivity of ultra-thin chemical vapor deposited hexagonal boron nitride films

    SciTech Connect (OSTI)

    Alam, M. T.; Haque, M. A., E-mail: mah37@psu.edu [Mechanical and Nuclear Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States); Bresnehan, M. S.; Robinson, J. A. [Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA and The Center for Two-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)] [Materials Science and Engineering, The Pennsylvania State University, University Park, Pennsylvania 16802, USA and The Center for Two-Dimensional and Layered Materials, The Pennsylvania State University, University Park, Pennsylvania 16802 (United States)

    2014-01-06T23:59:59.000Z

    Thermal conductivity of freestanding 10?nm and 20?nm thick chemical vapor deposited hexagonal boron nitride films was measured using both steady state and transient techniques. The measured value for both thicknesses, about 100?±?10?W m{sup ?1} K{sup ?1}, is lower than the bulk basal plane value (390?W m{sup ?1} K{sup ?1}) due to the imperfections in the specimen microstructure. Impressively, this value is still 100 times higher than conventional dielectrics. Considering scalability and ease of integration, hexagonal boron nitride grown over large area is an excellent candidate for thermal management in two dimensional materials-based nanoelectronics.

  6. Analytical evaluation of thermal conductance and heat capacities of one-dimensional material systems

    SciTech Connect (OSTI)

    Saygi, Salih [Department of Physics, Gaziosmanpasa University, Tokat, 60200 Turkey (Turkey)] [Department of Physics, Gaziosmanpasa University, Tokat, 60200 Turkey (Turkey)

    2014-02-15T23:59:59.000Z

    We theoretically predict some thermal properties versus temperature dependence of one dimensional (1D) material nanowire systems. A known method is used to provide an efficient and reliable analytical procedure for wide temperature range. Predicted formulas are expressed in terms of Bloch-Grüneisen functions and Debye functions. Computing results has proved that the expressions are in excellent agreement with the results reported in the literature even if it is in very low dimension limits of nanowire systems. Therefore the calculation method is a fully predictive approach to calculate thermal conductivity and heat capacities of nanowire material systems.

  7. Thermoelectric Properties of p-Type PbSe Nanowires Wenjie Liang1,3

    E-Print Network [OSTI]

    Yang, Peidong

    Thermoelectric Properties of p-Type PbSe Nanowires Wenjie Liang1,3 , Oded Rabin1,4 , Allon I-009-9039-2 Research Article Address correspondence to p_yang@berkeley.edu ABSTRACT The thermoelectric properties to 300 K. Thermal annealing of the PbSe nanowires allowed their thermoelectric properties

  8. An apparatus for the measurement of thermal conductivity of liquid neon 

    E-Print Network [OSTI]

    Jensen, Jerald Norman

    1967-01-01T23:59:59.000Z

    AN APPARATUS FOR THE MEASUREMENT OF THERMAL CONDUCTIVITY OF LIQUID NEON A Thesis By JERALD NORMAN JENSEN Submitted. to the Graduate College of the Texas A & M University in partial fulfillment of the requirements for the degree of MASTER... OF SCIENCE May 1967 Ma)or Su'bisect: Physics AN APPAHATUS FOH THE J'lEASURENENT OF THEHiiLM CONDUCTIVITY OF LIQUID NEOiV A Thesis JEHALD NOLAN JENSEN Approved as to style and content by: tH *i *f D p tm~t (I"ember) , i~ember Nay 1967 !$ ~c g tg...

  9. Effect of alkali addition on DC conductivity and thermal properties of vanadium-bismo-borate glasses

    SciTech Connect (OSTI)

    Khasa, S., E-mail: skhasa@rediff.com; Dahiya, M. S., E-mail: skhasa@rediff.com [Physics Department, Deenbandhu Chhotu Ram University of Science and Technology, Murthal-131039 (India); Agarwal, A. [Physics Department, Guru Jambheshwara University of Science and Technology, Hisar-125001 (India)

    2014-04-24T23:59:59.000Z

    The DC Conductivity and Differential Thermal Analysis of glasses with composition (30?x)Li{sub 2}O?xV{sub 2}O{sub 5}?20Bi{sub 2}O{sub 3}?50B{sub 2}O{sub 3}(x=15, 10, 5) has been carried out in order to study the effect of replacing the Transition Metal Oxide (TMO) with alkali oxide. A significant increase in the DC conductivity has been observed with increase in alkali content. Again the thermal measurements have shown the decrease in both glass transition temperature (T{sub g}) and crystallization temperature (T{sub x}). The Glass Stability (GS) and Glass Forming Ability (GFA) have also been calculated and these also were found to decrease with increase in alkali oxide content at the cost of TMO.

  10. Uncertainty Analysis on the Design of Thermal Conductivity Measurement by a Guarded Cut-Bar Technique

    SciTech Connect (OSTI)

    Jeff Phillips; Changhu Xing; Colby Jensen; Heng Ban1

    2011-07-01T23:59:59.000Z

    A technique adapted from the guarded-comparative-longitudinal heat flow method was selected for the measurement of the thermal conductivity of a nuclear fuel compact over a temperature range characteristic of its usage. This technique fulfills the requirement for non-destructive measurement of the composite compact. Although numerous measurement systems have been created based on the guarded comparative method, comprehensive systematic (bias) and measurement (precision) uncertainty associated with this technique have not been fully analyzed. In addition to the geometric effect in the bias error, which has been analyzed previously, this paper studies the working condition which is another potential error source. Using finite element analysis, this study showed the effect of these two types of error sources in the thermal conductivity measurement process and the limitations in the design selection of various parameters by considering their effect on the precision error. The results and conclusions provide valuable reference for designing and operating an experimental measurement system using this technique.

  11. Effect of phonon confinement on lattice thermal conductivity of lead Telluride quantum well structure

    SciTech Connect (OSTI)

    Tripathi, Madhvendra Nath, E-mail: ommadhav27@gmail.com [Department of Pure and Applied Physics, Guru Ghasidas Vishwavidyalaya, Bilaspur-495009, Chhattisgarh (India)

    2014-04-24T23:59:59.000Z

    The paper examines the effect of spatial confinement of acoustic phonons on average group velocity and consequently the lattice thermal conductivity of a free-standing PbTe quantum well structure and their temperature dependence. The average group velocity at 100 Å decreases 30% to the bulk value and falls more rapidly on reducing the width of quantum well. Moreover, the lattice thermal conductivity of 100 Å wide PbTe quantum well with value of 0.60 W/mK shows considerable decrease of 70% compared to it’s bulk value. It is observed that the effect of reduction in well width is less pronounce as temperature increases. This appears mainly due to dominance of umklapp processes over the confinement effects.

  12. Thermal Energy Harvesting with Thermoelectrics for Self-powered Sensors: With Applications to Implantable Medical Devices, Body Sensor Networks and Aging in Place

    E-Print Network [OSTI]

    Chen, Alic

    2011-01-01T23:59:59.000Z

    13! 1.4.2.3. Design of Wearable TEG’thermoelectric materials for TEGs can be utilized for low-14], [15]. 5. While the TEG shown in this work demonstrates

  13. Anomalous pressure dependence of thermal conductivities of large mass ratio compounds

    SciTech Connect (OSTI)

    Lindsay, Lucas R [ORNL; Broido, David [Boston College, Chestnut Hill; Carrete, Jesus [French Alternative Energies and Atomic Energy Commission (CEA), Grenoble; Mingo, Natalio [French Alternative Energies and Atomic Energy Commission (CEA), Grenoble; Reinecke, Tom [Naval Research Laboratory, Washington, D.C.

    2015-01-01T23:59:59.000Z

    The lattice thermal conductivities ( ) of binary compound materials are examined as a function of hydrostatic pressure, P, using a first-principles approach. Compound materials with relatively small mass ratios, such as MgO, show an increase in with P, consistent with measurements. Conversely, compounds with large mass ratios (e.g., BSb, BAs, BeTe, BeSe) exhibit decreasing with increasing P, a behavior that cannot be understood using simple theories of . This anomalous P dependence of arises from the fundamentally different nature of the intrinsic scattering processes for heat-carrying acoustic phonons in large mass ratio compounds compared to those with small mass ratios. This work demonstrates the power of first principles methods for thermal properties and advances the understanding of thermal transport in non-metals.

  14. Accepted by the Journal of Building Physics (2007) Microstructure and Thermal Conductivity of Hydrated Calcium Silicate Board Materials

    E-Print Network [OSTI]

    Bentz, Dale P.

    of Hydrated Calcium Silicate Board Materials Chi T. Do, Dale P. Bentz1 , and Paul E. Stutzman Building and pore size are examined for two calcium silicate boards of different densities. Thermal conductivities; radiation; thermal conductivity. Introduction In recent years, a variety of low-density calcium silicate

  15. PHYSICAL REVIEW B 84, 054203 (2011) Electrical and thermal conductivity of liquid sodium from first-principles calculations

    E-Print Network [OSTI]

    Alfè, Dario

    2011-01-01T23:59:59.000Z

    and technological point of view. For example, it is used as coolant in fast-breeding nuclear reactors, and in heatPHYSICAL REVIEW B 84, 054203 (2011) Electrical and thermal conductivity of liquid sodium from first on the electrical and thermal conductivity of liquid sodium at 400 K, calculated using density functional theory

  16. Effect of nanodot areal density and period on thermal conductivity in SiGe/Si nanodot superlattices

    E-Print Network [OSTI]

    Haller, Gary L.

    Effect of nanodot areal density and period on thermal conductivity in SiGe/Si nanodot superlattices-plane thermal conductivity in SiGe/Si nanodot superlattices NDSLs . For all ND areal densities considered, we found that in SiGe/Si NDSLs decreased monotonically with decreasing period and reached values lower than

  17. Unglazed transpired solar collector having a low thermal-conductance absorber

    DOE Patents [OSTI]

    Christensen, Craig B. (Boulder, CO); Kutscher, Charles F. (Golden, CO); Gawlik, Keith M. (Boulder, CO)

    1997-01-01T23:59:59.000Z

    An unglazed transpired solar collector using solar radiation to heat incoming air for distribution, comprising an unglazed absorber formed of low thermal-conductance material having a front surface for receiving the solar radiation and openings in the unglazed absorber for passage of the incoming air such that the incoming air is heated as it passes towards the front surface of the absorber and the heated air passes through the openings in the absorber for distribution.

  18. Unglazed transpired solar collector having a low thermal-conductance absorber

    DOE Patents [OSTI]

    Christensen, C.B.; Kutscher, C.F.; Gawlik, K.M.

    1997-12-02T23:59:59.000Z

    An unglazed transpired solar collector using solar radiation to heat incoming air for distribution, comprises an unglazed absorber formed of low thermal-conductance material having a front surface for receiving the solar radiation and openings in the unglazed absorber for passage of the incoming air such that the incoming air is heated as it passes towards the front surface of the absorber and the heated air passes through the openings in the absorber for distribution. 3 figs.

  19. Thermoelectric materials ternary penta telluride and selenide compounds

    DOE Patents [OSTI]

    Sharp, Jeffrey W. (Richardson, TX)

    2001-01-01T23:59:59.000Z

    Ternary tellurium compounds and ternary selenium compounds may be used in fabricating thermoelectric devices with a thermoelectric figure of merit (ZT) of 1.5 or greater. Examples of such compounds include Tl.sub.2 SnTe.sub.5, Tl.sub.2 GeTe.sub.5, K.sub.2 SnTe.sub.5 and Rb.sub.2 SnTe.sub.5. These compounds have similar types of crystal lattice structures which include a first substructure with a (Sn, Ge) Te.sub.5 composition and a second substructure with chains of selected cation atoms. The second substructure includes selected cation atoms which interact with selected anion atoms to maintain a desired separation between the chains of the first substructure. The cation atoms which maintain the desired separation between the chains occupy relatively large electropositive sites in the resulting crystal lattice structure which results in a relatively low value for the lattice component of thermal conductivity (.kappa..sub.g). The first substructure of anion chains indicates significant anisotropy in the thermoelectric characteristics of the resulting semiconductor materials.

  20. Thermoelectric materials: ternary penta telluride and selenide compounds

    DOE Patents [OSTI]

    Sharp, Jeffrey W. (Richardson, TX)

    2002-06-04T23:59:59.000Z

    Ternary tellurium compounds and ternary selenium compounds may be used in fabricating thermoelectric devices with a thermoelectric figure of merit (ZT) of 1.5 or greater. Examples of such compounds include Tl.sub.2 SnTe.sub.5, Tl.sub.2 GeTe.sub.5, K.sub.2 SnTe.sub.5 and Rb.sub.2 SnTe.sub.5. These compounds have similar types of crystal lattice structures which include a first substructure with a (Sn, Ge) Te.sub.5 composition and a second substructure with chains of selected cation atoms. The second substructure includes selected cation atoms which interact with selected anion atoms to maintain a desired separation between the chains of the first substructure. The cation atoms which maintain the desired separation between the chains occupy relatively large electropositive sites in the resulting crystal lattice structure which results in a relatively low value for the lattice component of thermal conductivity (.kappa..sub.g). The first substructure of anion chains indicates significant anisotropy in the thermoelectric characteristics of the resulting semiconductor materials.

  1. The role of interfacial layers in the enhanced thermal conductivity of nanofluids : a renovated Hamilton-Crosser model.

    SciTech Connect (OSTI)

    Yu, W.; Choi, S. U.-S.; Energy Technology

    2004-08-01T23:59:59.000Z

    We previously developed a renovated Maxwell model for the effective thermal conductivity of nanofluids and determined that the solid/liquid interfacial layers play an important role in the enhanced thermal conductivity of nanofluids. However, this renovated Maxwell model is limited to suspensions with spherical particles. Here, we extend the Hamilton--Crosser model for suspensions of nonspherical particles to include the effect of a solid/liquid interface. The solid/liquid interface is described as a confocal ellipsoid with a solid particle. The new model for the three-phase suspensions is mathematically expressed in terms of the equivalent thermal conductivity and equivalent volume fraction of anisotropic complex ellipsoids, as well as an empirical shape factor. With a generalized empirical shape factor, the renovated Hamilton-Crosser model correctly predicts the magnitude of the thermal conductivity of nanotube-in-oil nanofluids. At present, this new model is not able to predict the nonlinear behavior of the nanofluid thermal conductivity.

  2. Probing thermoelectric transport with cold atoms

    E-Print Network [OSTI]

    Charles Grenier; Corinna Kollath; Antoine Georges

    2013-11-10T23:59:59.000Z

    We propose experimental protocols to reveal thermoelectric and thermal effects in the transport properties of ultracold fermionic atoms, using the two-terminal setup recently realized at ETH. We show in particular that, for two reservoirs having equal particle numbers but different temperatures initially, the observation of a transient particle number imbalance during equilibration is a direct evidence of thermoelectric (off-diagonal) transport coefficients. This is a time-dependent analogue of the Seebeck effect, and a corresponding analogue of the Peltier effect can be proposed. We reveal that in addition to the thermoelectric coupling of the constriction a thermoelectric coupling also arises due to the finite dilatation coefficient of the reservoirs. We present a theoretical analysis of the protocols, and assess their feasibility by estimating the corresponding temperature and particle number imbalances in realistic current experimental conditions.

  3. Magneto thermal conductivity of superconducting Nb with intermediate level of impurity

    SciTech Connect (OSTI)

    L.S. Sharath Chandra, M.K. Chattopadhyay, S.B. Roy, V.C. Sahni, G.R. Myneni

    2012-03-01T23:59:59.000Z

    Niobium materials with intermediate purity level are used for fabrication of superconducting radio frequency cavities (SCRF), and thermal conductivity is an important parameter influencing the performance of such SCRF cavities. We report here the temperature and magnetic field dependence of thermal conductivity {kappa} for superconducting niobium (Nb) samples, for which the electron mean free path I{sub e}, the phonon mean free path I{sub g}, and the vortex core diameter 2r{sub C} are of the same order of magnitude. The measured thermal conductivity is analyzed using the effective gap model (developed for I{sub e} >> 2r{sub C} (Dubeck et al 1963 Phys. Rev. Lett. 10 98)) and the normal core model (developed for I{sub e} << 2r{sub C} (Ward and Dew-Hughes 1970 J. Phys. C: Solid St. Phys. 3 2245)). However, it is found that the effective gap model is not suitable for low temperatures when I{sub e} {approx} 2r{sub C}. The normal core model, on the other hand, is able to describe {kappa}(T,H) over the entire temperature range except in the field regime between H{sub C1} and H{sub C2} i.e. in the mixed state. It is shown that to understand the complete behavior of {kappa} in the mixed state, the scattering of quasi-particles from the vortex cores and the intervortex quasi-particle tunneling are to be invoked. The quasi-particle scattering from vortices for the present system is understood in terms of the framework of Sergeenkov and Ausloos (1995 Phys. Rev. B 52 3614) extending their approach to the case of Nb. The intervortex tunneling is understood within the framework of Schmidbauer et al (1970 Z. Phys. 240 30). Analysis of the field dependence of thermal conductivity shows that while the quasi-particle scattering from vortices dominates in the low fields, the intervortex quasi-particle tunneling dominates in high fields. Analysis of the temperature dependence of thermal conductivity shows that while the quasi-particle scattering is dominant at low temperatures, the intervortex quasi-particle tunneling is dominant at high temperatures.

  4. Determination of temperature-dependent heat conductivity and thermal diffusivity of waste glass melter feed

    SciTech Connect (OSTI)

    Pokorny, Richard; Rice, Jarrett A.; Schweiger, Michael J.; Hrma, Pavel R.

    2013-06-01T23:59:59.000Z

    The cold cap is a layer of reacting glass batch floating on the surface of melt in an all-electric continuous glass melter. The heat needed for the conversion of the melter feed to molten glass must be transferred to and through the cold cap. Since the heat flux into the cold cap determines the rate of melting, the heat conductivity is a key property of the reacting feed. We designed an experimental setup consisting of a large cylindrical crucible with an assembly of thermocouples that monitors the evolution of the temperature field while the crucible is heated at a constant rate. Then we used two methods to calculate the heat conductivity and thermal diffusivity of the reacting feed: the approximation of the temperature field by polynomial functions and the finite-volume method coupled with least-squares analysis. Up to 680°C, the heat conductivity of the reacting melter feed was represented by a linear function of temperature.

  5. A Low Hysteresis NiTiFe Shape Memory Alloy Based Thermal Conduction Switch

    SciTech Connect (OSTI)

    Lemanski, J. L.; Krishnan, V. B.; Manjeri, R. Mahadevan; Vaidyanathan, R. [University of Central Florida, Orlando, Florida, 32816 (United States); Notardonato, W. U. [National Aeronautics and Space Administration, Kennedy Space Center, Florida, 32899 (United States)

    2006-03-31T23:59:59.000Z

    Shape memory alloys possess the ability to return to a preset shape by undergoing a solid state phase transformation at a particular temperature. This work reports on the development and testing of a low temperature thermal conduction switch that incorporates a NiTiFe shape memory element for actuation. The switch was developed to provide a variable conductive pathway between liquid methane and liquid oxygen dewars in order to passively regulate the temperature of methane. The shape memory element in the switch undergoes a rhombohedral or R-phase transformation that is associated with a small hysteresis (typically 1-2 deg. C) and offers the advantage of precision control over a set temperature range. For the NiTiFe alloy used, its thermomechanical processing, subsequent characterization using dilatometry, differential scanning calorimetry and implementation in the conduction switch configuration are addressed.

  6. Nanocomposites as thermoelectric materials

    E-Print Network [OSTI]

    Hao, Qing

    2010-01-01T23:59:59.000Z

    Thermoelectric materials have attractive applications in electric power generation and solid-state cooling. The performance of a thermoelectric device depends on the dimensionless figure of merit (ZT) of the material, ...

  7. Thermal Transport Measurement of Silicon-Germanium Nanowires

    E-Print Network [OSTI]

    Gwak, Yunki

    2010-10-12T23:59:59.000Z

    to the enhanced boundary scattering. Among the nanoscale semiconductor materials, Silicon-Germanium(SiGe) alloy nanowire is a promising candidate for thermoelectric materials The thermal conductivities of SiGe core-shell nanowires with core diameters of 96nm, 129...

  8. High-Throughput Computational Screening of thermal conductivity, Debye temperature and Gruneisen parameter

    E-Print Network [OSTI]

    Curtarolo, Stefano

    , such us the development of new thermoelectric materials1,2 , heat sink materials for ther- mal management and Materials Science, Duke University, Durham, North Carolina 27708, USA 2 Department of Materials Science Department of Physics and Department of Chemistry, University of North Texas, Denton TX 4 Materials Science

  9. Analysis of Thermoelectric Properties of Scaled Silicon Nanowires Using an Atomistic Tight-Binding Model

    E-Print Network [OSTI]

    1 Analysis of Thermoelectric Properties of Scaled Silicon Nanowires Using an Atomistic Tight Abstract Low dimensional materials provide the possibility of improved thermoelectric performance due. As a result of suppressed phonon conduction, large improvements on the thermoelectric figure of merit, ZT

  10. Measurement of temperature-dependent thermal conductivity and viscosity of TiO{sub 2}-water nanofluids

    SciTech Connect (OSTI)

    Duangthongsuk, Weerapun; Wongwises, Somchai [Fluid Mechanics, Thermal Engineering and Multiphase Flow Research Lab. (FUTURE), Department of Mechanical Engineering, King Mongkut's University of Technology Thonburi, 126 Bangmod, Bangkok 10140 (Thailand)

    2009-04-15T23:59:59.000Z

    Nanofluid is an innovative heat transfer fluid with superior potential for enhancing the heat transfer performance of conventional fluids. Many attempts have been made to investigate its thermal conductivity and viscosity, which are important thermophysical properties. No definitive agreements have emerged, however, about these properties. This article reports the thermal conductivity and dynamic viscosity of nanofluids experimentally. TiO{sub 2} nanoparticles dispersed in water with volume concentration of 0.2-2 vol.% are used in the present study. A transient hot-wire apparatus is used for measuring the thermal conductivity of nanofluids whereas the Bohlin rotational rheometer (Malvern Instrument) is used to measure the viscosity of nanofluids. The data are collected for temperatures ranging from 15 C to 35 C. The results show that the measured viscosity and thermal conductivity of nanofluids increased as the particle concentrations increased and are higher than the values of the base liquids. Furthermore, thermal conductivity of nanofluids increased with increasing nanofluid temperatures and, conversely, the viscosity of nanofluids decreased with increasing temperature of nanofluids. Moreover, the measured thermal conductivity and viscosity of nanofluids are quite different from the predicted values from the existing correlations and the data reported by other researchers. Finally, new thermophysical correlations are proposed for predicting the thermal conductivity and viscosity of nanofluids. (author)

  11. Transport in Charged Colloids Driven by Thermoelectricity

    E-Print Network [OSTI]

    Alois Würger

    2014-01-29T23:59:59.000Z

    We study the thermal diffusion coefficient DT of a charged colloid in a temperature gradient, and find that it is to a large extent determined by the thermoelectric response of the electrolyte solution. The thermally induced salinity gradient leads in general to a strong increase with temperature. The difference of the heat of transport of coions and counterions gives rise to a thermoelectric field that drives the colloid to the cold or to the warm, depending on the sign of its charge. Our results provide an explanation for recent experimental findings on thermophoresis in colloidal suspensions.

  12. Prediction of Thermal Conductivity for Irradiated SiC/SiC Composites by Informing Continuum Models with Molecular Dynamics Data

    SciTech Connect (OSTI)

    Nguyen, Ba Nghiep; Gao, Fei; Henager, Charles H.; Kurtz, Richard J.

    2014-05-01T23:59:59.000Z

    This article proposes a new method to estimate the thermal conductivity of SiC/SiC composites subjected to neutron irradiation. The modeling method bridges different scales from the atomic scale to the scale of a 2D SiC/SiC composite. First, it studies the irradiation-induced point defects in perfect crystalline SiC using molecular dynamics (MD) simulations to compute the defect thermal resistance as a function of vacancy concentration and irradiation dose. The concept of defect thermal resistance is explored explicitly in the MD data using vacancy concentrations and thermal conductivity decrements due to phonon scattering. Point defect-induced swelling for chemical vapor deposited (CVD) SiC as a function of irradiation dose is approximated by scaling the corresponding MD results for perfect crystal ?-SiC to experimental data for CVD-SiC at various temperatures. The computed thermal defect resistance, thermal conductivity as a function of grain size, and definition of defect thermal resistance are used to compute the thermal conductivities of CVD-SiC, isothermal chemical vapor infiltrated (ICVI) SiC and nearly-stoichiometric SiC fibers. The computed fiber and ICVI-SiC matrix thermal conductivities are then used as input for an Eshelby-Mori-Tanaka approach to compute the thermal conductivities of 2D SiC/SiC composites subjected to neutron irradiation within the same irradiation doses. Predicted thermal conductivities for an irradiated Tyranno-SA/ICVI-SiC composite are found to be comparable to available experimental data for a similar composite ICVI-processed with these fibers.

  13. Thermal interface conductance across a graphene/hexagonal boron nitride heterojunction

    SciTech Connect (OSTI)

    Chen, Chun-Chung; Li, Zhen; Cronin, Stephen B. [Department of Electrical Engineering, University of Southern California, Los Angeles, California 90089 (United States); Shi, Li [Department of Mechanical Engineering and Texas Materials Institute, University of Texas at Austin, Austin, Texas 78712 (United States)

    2014-02-24T23:59:59.000Z

    We measure thermal transport across a graphene/hexagonal boron nitride (h-BN) interface by electrically heating the graphene and measuring the temperature difference between the graphene and BN using Raman spectroscopy. Because the temperature of the graphene and BN are measured optically, this approach enables nanometer resolution in the cross-plane direction. A temperature drop of 60?K can be achieved across this junction at high electrical powers (14 mW). Based on the temperature difference and the applied power data, we determine the thermal interface conductance of this junction to be 7.4?×?10{sup 6}?Wm{sup ?2}K{sup ?1}, which is below the 10{sup 7}–10{sup 8}?Wm{sup ?2}K{sup ?1} values previously reported for graphene/SiO{sub 2} interface.

  14. Fabrication of high thermal conductivity arrays of carbon nanotubes and their composites

    DOE Patents [OSTI]

    Geohegan, David B. (Knoxville, TN) [Knoxville, TN; Ivanov, Ilya N. (Knoxville, TN) [Knoxville, TN; Puretzky, Alexander A [Knoxville, TN

    2010-07-27T23:59:59.000Z

    Methods and apparatus are described for fabrication of high thermal conductivity arrays of carbon nanotubes and their composites. A composition includes a vertically aligned nanotube array including a plurality of nanotubes characterized by a property across substantially all of the vertically aligned nanotube array. A method includes depositing a vertically aligned nanotube array that includes a plurality of nanotubes; and controlling a deposition rate of the vertically aligned nanotubes array as a function of an in situ monitored property of the plurality of nanotubes.

  15. Subsurface Temperature, Moisture, Thermal Conductivity and Heat Flux, Barrow, Area A, B, C, D

    DOE Data Explorer [Office of Scientific and Technical Information (OSTI)]

    Cable, William; Romanovsky, Vladimir

    Subsurface temperature data are being collected along a transect from the center of the polygon through the trough (and to the center of the adjacent polygon for Area D). Each transect has five 1.5m vertical array thermistor probes with 16 thermistors each. This dataset also includes soil pits that have been instrumented for temperature, water content, thermal conductivity, and heat flux at the permafrost table. Area C has a shallow borehole of 2.5 meters depth is instrumented in the center of the polygon.

  16. Thermoelectric Behavior of Flexible Organic Nanocomposites with Carbon Nanotubes

    E-Print Network [OSTI]

    Choi, Kyung Who

    2013-12-03T23:59:59.000Z

    with ~100 S/m of electrical conductivity, resulting ~10,000 µW/m-K2 of power factor. The result of this study shows that organic thermoelectric materials would be a promising approach for thermoelectric applications with light-weight and non-toxic nature....

  17. ANSYS Thermoelectric Generator (TEG) Preparing the ANSYS Workbench

    E-Print Network [OSTI]

    Lee, Ho Sung

    ANSYS Thermoelectric Generator (TEG) Tutorial Preparing the ANSYS Workbench 1) Go Start Menu All-click Thermal-Electric at the top of the Project Schematic pane and select Rename as TEG Ex 3.1 Tutorial. 4

  18. MODELING THE TRANSVERSE THERMAL CONDUCTIVITY OF 2D-SICF/SIC COMPOSITES

    SciTech Connect (OSTI)

    Youngblood, Gerald E.; Senor, David J.; Jones, Russell H.

    2002-09-01T23:59:59.000Z

    A hierarchical model was developed to describe the effective transverse thermal conductivity, K effective, of a 2D-SiC/SiC composite made from stacked and infiltrated woven fabric layers in terms of constituent properties and microstructural and architectural variables. The model includes the expected effects of fiber-matrix interfacial conductance as well as the effects of high fiber packing fractions within individual tows and the non-uniform nature of 2D-fabric layers that include a significant amount of interlayer porosity. Model predictions were obtained for two versions of DuPont 2D-Hi Nicalon(Trademark)/PyC/ICVI-SiC composite, one with a thin (0.110 micron) and the other with a thick (1.040 micron) PyC fiber coating. The model predicts that the matrix porosity content and porosity shape factor have a major influence on K effective(T) for such a composite.

  19. Thermoelectric Properties of Au- Containing Type-I Clathrates Ba8AuxGa16-3xGe30+2x

    SciTech Connect (OSTI)

    Ye, Zuxin [Optimal Inc., Plymouth, Michigan 48170, USA] [Optimal Inc., Plymouth, Michigan 48170, USA; Cho, Jung Young [Optimal Inc., Plymouth, Michigan 48170, USA] [Optimal Inc., Plymouth, Michigan 48170, USA; Tessema, Misle M. [Optimal Inc., Plymouth, Michigan 48170, USA] [Optimal Inc., Plymouth, Michigan 48170, USA; Salvador, James R. [General Motors, Global Research and Development] [General Motors, Global Research and Development; Waldo, Richard A. [General Motors, Global Research and Development] [General Motors, Global Research and Development; Yang, Jihui [University of Washington] [University of Washington; Wang, Hsin [ORNL] [ORNL; Cai, Wei [ORNL] [ORNL; Kirkham, Melanie J [ORNL] [ORNL; Yang, Jiong [Chinese Academy of Sciences (CAS)] [Chinese Academy of Sciences (CAS); Zhang, Wenqing [Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS)] [Shanghai Institute of Ceramics, Chinese Academy of Sciences (SICCAS)

    2014-01-01T23:59:59.000Z

    Type I clathrates, with compositions based on Ba8Ga16Ge30, are a class of promising thermoelectric materials due to their intrinsically low thermal conductivity. It has been demonstrated previously that the thermoelectric performance can be improved by transition metal substitution of the framework atoms. In this study, the effects of Au substitution for Ga/Ge on thermal and electrical transport properties of type I clathrate compounds have been investigated. Polycrystalline samples with a large range of Au content have been synthesized using conventional solid state techniques with the actual compositions of resulting materials approximately following Zintl-Klemm rules. The charge carrier type changes from electrons (n) to holes (p) as the Au content increases. The Seebeck coefficient (S) and power factor (S2/ where is the electrical resistivity) were improved by Au substitution and the resulting overall thermoelectric properties were enhanced by Au substitution with a thermoelectric figure of merit ZT ~ 0.63 at temperature T = 740 K for the composition Ba8Au5.47Ge39.96. The results presented herein show that Au-containing type I clathrates are promising p-type thermoelectric materials for high temperature applications.

  20. Thermal Conductivity Enhancement of High Temperature Phase Change Materials for Concentrating Solar Power Plant Applications

    E-Print Network [OSTI]

    Roshandell, Melina

    2013-01-01T23:59:59.000Z

    Proceedings on thermal energy storage and energy conversion;polymer microcomposites for thermal energy storage. SAE SocLow temperature thermal energy storage: a state of the art

  1. Thermal Conductivity Enhancement of High Temperature Phase Change Materials for Concentrating Solar Power Plant Applications

    E-Print Network [OSTI]

    Roshandell, Melina

    2013-01-01T23:59:59.000Z

    materials (PCM) in solar thermal concentrating technologyeffective and efficient solar thermal electricity generatorbeen considered for solar thermal energy storages. These are

  2. Thermal Conductivity Enhancement of High Temperature Phase Change Materials for Concentrating Solar Power Plant Applications

    E-Print Network [OSTI]

    Roshandell, Melina

    2013-01-01T23:59:59.000Z

    been considered for solar thermal energy storages. These arePCMs for thermal energy storage in solar driven residentialfluid and thermal energy storage medium in the solar heat

  3. Enhancement in figure-of-merit with superlattices structures for thin-film thermoelectric devices

    SciTech Connect (OSTI)

    Venkatasubramanian, R.; Colpitts, T.

    1997-07-01T23:59:59.000Z

    Thin-film superlattice (SL) structures in thermoelectric materials are shown to be a promising approach to obtaining an enhanced figure-of-merit, ZT, compared to conventional, state-of-the-art bulk alloyed materials. In this paper the authors describe experimental results on Bi{sub 2}Te{sub 3}/Sb{sub 2}Te{sub 3} and Si/Ge SL structures, relevant to thermoelectric cooling and power conversion, respectively. The short-period Bi{sub 2}Te{sub 3} and Si/Ge SL structures appear to indicate reduced thermal conductivities compared to alloys of these materials. From the observed behavior of thermal conductivity values in the Bi{sub 2}Te{sub 3}/Sb{sub 2}Te{sub 3} SL structures, a distinction is made where certain types of periodic structures may correspond to an ordered alloy rather than an SL, and therefore, do not offer a significant reduction in thermal conductivity values. The study also indicates that SL structures, with little or weak quantum-confinement, also offer an improvement in thermoelectric power factor over conventional alloys. They present power factor and electrical transport data in the plane of the SL interfaces to provide preliminary support for the arguments on reduced alloy scattering and impurity scattering in Bi{sub 2}Te{sub 3}/Sb{sub 2}Te{sub 3} and Si/Ge SL structures. These results, though tentative due to the possible role of the substrate and the developmental nature of the 3-{omega} method used to determine thermal conductivity values, suggest that the short-period SL structures potentially offer factorial improvements in the three-dimensional figure-of-merit (ZT3D) compared to current state-of-the-art bulk alloys. An approach to a thin-film thermoelectric device called a Bipolarity-Assembled, Series-Inter-Connected Thin-Film Thermoelectric Device (BASIC-TFTD) is introduced to take advantage of these thin-film SL structures.

  4. Preparation of silica aerogels with improved mechanical properties and extremely low thermal conductivities through modified sol-gel process

    E-Print Network [OSTI]

    Zuo, Yanjia

    2010-01-01T23:59:59.000Z

    Reported silica aerogels have a thermal conductivity as low as 15 mW/mK. The fragility of silica aerogels, however, makes them impractical for structural applications. The purpose of the study is to improve the ductility ...

  5. Evaluation of the Thermal Performance for a Wire Mesh/Hollow Glass Microsphere Composite Structure as a Conduction Barrier

    E-Print Network [OSTI]

    Mckenna, Sean

    2010-01-15T23:59:59.000Z

    An experimental investigation exploring the use of wire mesh/hollow glass microsphere combination for use as thermal insulation was conducted with the aim to conclude whether or not it represents a superior insulation technology to those...

  6. Nonlinear vs. bolometric radiation response and phonon thermal conductance in graphene-superconductor junctions

    SciTech Connect (OSTI)

    Vora, Heli; Nielsen, Bent; Du, Xu [Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York (United States)

    2014-02-21T23:59:59.000Z

    Graphene is a promising candidate for building fast and ultra-sensitive bolometric detectors due to its weak electron-phonon coupling and low heat capacity. In order to realize a practical graphene-based bolometer, several important issues, including the nature of radiation response, coupling efficiency to the radiation and the thermal conductance need to be carefully studied. Addressing these issues, we present graphene-superconductor junctions as a viable option to achieve efficient and sensitive bolometers, with the superconductor contacts serving as hot electron barriers. For a graphene-superconductor device with highly transparent interfaces, the resistance readout in the presence of radio frequency radiation is dominated by non-linear response. On the other hand, a graphene-superconductor tunnel device shows dominantly bolometric response to radiation. For graphene devices fabricated on SiO{sub 2} substrates, we confirm recent theoretical predictions of T{sup 2} temperature dependence of phonon thermal conductance in the presence of disorder in the graphene channel at low temperatures.

  7. Manipulator having thermally conductive rotary joint for transferring heat from a test specimen

    DOE Patents [OSTI]

    Haney, S.J.; Stulen, R.H.; Toly, N.F.

    1983-05-03T23:59:59.000Z

    A manipulator for rotatably moving a test specimen in an ultra-high vacuum chamber includes a translational unit movable in three mutually perpendicular directions. A manipulator frame is rigidly secured to the translational unit for rotatably supporting a rotary shaft. A first copper disc is rigidly secured to an end of the rotary shaft for rotary movement within the vacuum chamber. A second copper disc is supported upon the first disc. The second disc receives a cryogenic cold head and does not rotate with the first disc. The second disc receives a cryogenic cold head and does not rotate with the first disc. A sapphire plate is interposed between the first and second discs to prevent galling of the copper material while maintaining high thermal conductivity between the first and second discs. A spring is disposed on the shaft to urge the second disc toward the first disc and compressingly engage the interposed sapphire plate. A specimen mount is secured to the first disc for rotation within the vacuum chamber. The specimen maintains high thermal conductivity with the second disc receiving the cryogenic transfer line.

  8. Manipulator having thermally conductive rotary joint for transferring heat from a test specimen

    DOE Patents [OSTI]

    Haney, Steven J. (Tracy, CA); Stulen, Richard H. (Livermore, CA); Toly, Norman F. (Livermore, CA)

    1985-01-01T23:59:59.000Z

    A manipulator for rotatably moving a test specimen in an ultra-high vacuum chamber includes a translational unit movable in three mutually perpendicular directions. A manipulator frame is rigidly secured to the translational unit for rotatably supporting a rotary shaft. A first copper disc is rigidly secured to an end of the rotary shaft for rotary movement within the vacuum chamber. A second copper disc is supported upon the first disc. The second disc receives a cryogenic cold head and does not rotate with the first disc. A sapphire plate is interposed between the first and second discs to prevent galling of the copper material while maintaining high thermal conductivity between the first and second discs. A spring is disposed on the shaft to urge the second disc toward the first disc and compressingly engage the interposed sapphire plate. A specimen mount is secured to the first disc for rotation within the vacuum chamber. The specimen maintains high thermal conductivity with the second disc receiving the cryogenic transfer line.

  9. Polymer Composites with Enhanced Thermal Conductivity: This research is funded by Honeywell Corporation and the Florida High Tech Corridor.

    E-Print Network [OSTI]

    Harmon, Julie P.

    Polymer Composites with Enhanced Thermal Conductivity: This research is funded by Honeywell/mK (50). Earlier work with Honeywell focused on the development of boron nitride/epoxy composites. We. Encouraging results prompted Honeywell, Inc to file a patent application with us (53). #12;The target thermal

  10. Impacts of Soil and Pipe Thermal Conductivity on Performance of Horizontal Pipe in a Ground-source Heat Pump

    E-Print Network [OSTI]

    Song, Y.; Yao, Y.; Na, W.

    2006-01-01T23:59:59.000Z

    In this paper the composition and thermal property of soil are discussed. The main factors that impact the soil thermal conductivity and several commonly-used pipe materials are studied. A model of heat exchanger with horizontal pipes of ground-source...

  11. IEEE TRANSACTIONS ON COMPONENTS AND PACKAGING TECHNOLOGIES, VOL. 32, NO. 2, JUNE 2009 447 Temperature Profile Inside Microscale Thermoelectric

    E-Print Network [OSTI]

    Temperature Profile Inside Microscale Thermoelectric Module Acquired Using Near-Infrared Thermoreflectance high-resolution thermal images of the electrical contacts inside an active thermoelectric micromodule-scale thermoelectric modules. By determining localized sources of Joule heating, one can identify manufacturing errors

  12. Thermoelectric materials having porosity

    DOE Patents [OSTI]

    Heremans, Joseph P.; Jaworski, Christopher M.; Jovovic, Vladimir; Harris, Fred

    2014-08-05T23:59:59.000Z

    A thermoelectric material and a method of making a thermoelectric material are provided. In certain embodiments, the thermoelectric material comprises at least 10 volume percent porosity. In some embodiments, the thermoelectric material has a zT greater than about 1.2 at a temperature of about 375 K. In some embodiments, the thermoelectric material comprises a topological thermoelectric material. In some embodiments, the thermoelectric material comprises a general composition of (Bi.sub.1-xSb.sub.x).sub.u(Te.sub.1-ySe.sub.y).sub.w, wherein 0.ltoreq.x.ltoreq.1, 0.ltoreq.y.ltoreq.1, 1.8.ltoreq.u.ltoreq.2.2, 2.8.ltoreq.w.ltoreq.3.2. In further embodiments, the thermoelectric material includes a compound having at least one group IV element and at least one group VI element. In certain embodiments, the method includes providing a powder comprising a thermoelectric composition, pressing the powder, and sintering the powder to form the thermoelectric material.

  13. High Temperature Integrated Thermoelectric Ststem and Materials

    SciTech Connect (OSTI)

    Mike S. H. Chu

    2011-06-06T23:59:59.000Z

    The final goal of this project is to produce, by the end of Phase II, an all ceramic high temperature thermoelectric module. Such a module design integrates oxide ceramic n-type, oxide ceramic p-type materials as thermoelectric legs and oxide ceramic conductive material as metalizing connection between n-type and p-type legs. The benefits of this all ceramic module are that it can function at higher temperatures (> 700 C), it is mechanically and functionally more reliable and it can be scaled up to production at lower cost. With this all ceramic module, millions of dollars in savings or in new opportunities recovering waste heat from high temperature processes could be made available. A very attractive application will be to convert exhaust heat from a vehicle to reusable electric energy by a thermoelectric generator (TEG). Phase I activities were focused on evaluating potential n-type and p-type oxide compositions as the thermoelectric legs. More than 40 oxide ceramic powder compositions were made and studied in the laboratory. The compositions were divided into 6 groups representing different material systems. Basic ceramic properties and thermoelectric properties of discs sintered from these powders were measured. Powders with different particles sizes were made to evaluate the effects of particle size reduction on thermoelectric properties. Several powders were submitted to a leading thermoelectric company for complete thermoelectric evaluation. Initial evaluation showed that when samples were sintered by conventional method, they had reasonable values of Seebeck coefficient but very low values of electrical conductivity. Therefore, their power factors (PF) and figure of merits (ZT) were too low to be useful for high temperature thermoelectric applications. An unconventional sintering method, Spark Plasma Sintering (SPS) was determined to produce better thermoelectric properties. Particle size reduction of powders also was found to have some positive benefits. Two composition systems, specifically 1.0 SrO - 0.8 x 1.03 TiO2 - 0.2 x 1.03 NbO2.5 and 0.97 TiO2 - 0.03 NbO2.5, have been identified as good base line compositions for n-type thermoelectric compositions in future module design. Tests of these materials at an outside company were promising using that company's processing and material expertise. There was no unique p-type thermoelectric compositions identified in phase I work other than several current cobaltite materials. Ca3Co4O9 will be the primary p-type material for the future module design until alternative materials are developed. BaTiO3 and rare earth titanate based dielectric compositions show both p-type and n-type behavior even though their electrical conductivities were very low. Further research and development of these materials for thermoelectric applications is planned in the future. A preliminary modeling and optimization of a thermoelectric generator (TEG) that uses the n-type 1.0 SrO - 1.03 x 0.8 TiO2 - 1.03 x 0.2 NbO2.5 was performed. Future work will combine development of ceramic powders and manufacturing expertise at TAM, development of SPS at TAM or a partner organization, and thermoelectric material/module testing, modeling, optimization, production at several partner organizations.

  14. Microscale Thermoelectric Cooling Elements (TECs) are being proposed to cool down an integrated circuit to maintain its performance. The maximum cooling power of microscale TECs is significantly reduced by the interfacial resistance. For our

    E-Print Network [OSTI]

    ICT 2008 1 Abstract Microscale Thermoelectric Cooling Elements (TECs) are being proposed to cool act as a good guideline for two-dimensional analysis and assembly of TECs. Key Words - Thermoelectric by the thermal power at the hotspot regions. Microscale Thermoelectric Cooling Elements (TECs) or Thermoelectric

  15. Structural, electrical, and thermoelectric properties of bismuth telluride: Silicon/carbon nanocomposites thin films

    SciTech Connect (OSTI)

    Agarwal, Khushboo; Mehta, B. R., E-mail: brmehta@physics.iitd.ac.in [Thin Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016 (India)

    2014-08-28T23:59:59.000Z

    In this study, the effect of the presence of secondary phases on the structural, electrical, and thermoelectric properties of nanocomposite Bi{sub 2}Te{sub 3} films prepared by co-sputtering of silicon and carbon with Bi{sub 2}Te{sub 3} has been investigated. Growth temperature and the presence of Si and C phase are observed to have a strong effect on the topography and orientation of crystallites. X-ray diffraction study demonstrates that Bi{sub 2}Te{sub 3} and Bi{sub 2}Te{sub 3}:C samples have preferred (0 0 15) orientation in comparison to Bi{sub 2}Te{sub 3}:Si sample, which have randomly oriented crystallites. Atomic force, conducting atomic force, and scanning thermal microscopy analysis show significant differences in topographical, electrical, and thermal conductivity contrasts in Bi{sub 2}Te{sub 3}:Si and Bi{sub 2}Te{sub 3}:C samples. Due to the randomly oriented crystallites and the presence of Si along the crystallite boundaries, appreciable Seebeck coefficient, higher electrical conductivity, and lower thermal conductivity is achieved resulting in relatively higher value of power factor (3.71 mW K{sup ?2} m{sup ?1}) for Bi{sub 2}Te{sub 3}:Si sample. This study shows that by incorporating a secondary phase along crystallite boundaries, microstructural, electrical, and thermoelectric properties of the composite samples can be modified.

  16. Determination of heat conductivity and thermal diffusivity of waste glass melter feed: Extension to high temperatures

    SciTech Connect (OSTI)

    Rice, Jarrett A. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Pokorny, Richard [Inst. of Chemical Technology, Prague (Czech Republic); Schweiger, Michael J. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Hrma, Pavel R. [Pacific Northwest National Laboratory (PNNL), Richland, WA (United States); Pohang Univ. of Science and Technology (Korea, Republic of)

    2014-06-01T23:59:59.000Z

    The heat conductivity ({lambda}) and the thermal diffusivity (a) of reacting glass batch, or melter feed, control the heat flux into and within the cold cap, a layer of reacting material floating on the pool of molten glass in an all-electric continuous waste glass melter. After previously estimating {lambda} of melter feed at temperatures up to 680 deg C, we focus in this work on the {lambda}(T) function at T > 680 deg C, at which the feed material becomes foamy. We used a customized experimental setup consisting of a large cylindrical crucible with an assembly of thermocouples, which monitored the evolution of the temperature field while the crucible with feed was heated at a constant rate from room temperature up to 1100°C. Approximating measured temperature profiles by polynomial functions, we used the heat transfer equation to estimate the {lambda}(T) approximation function, which we subsequently optimized using the finite-volume method combined with least-squares analysis. The heat conductivity increased as the temperature increased until the feed began to expand into foam, at which point the conductivity dropped. It began to increase again as the foam turned into a bubble-free glass melt. We discuss the implications of this behavior for the mathematical modeling of the cold cap.

  17. High Thermal Conductivity UO2-BeO Nulcear Fuel: Neutronic Performance Assessments and Overview of Fabrication

    E-Print Network [OSTI]

    Naramore, Michael J

    2010-08-03T23:59:59.000Z

    The objective of this work was to evaluate a new high conductivity nuclear fuel form. Uranium dioxide (UO2) is a very effective nuclear fuel, but it’s performance is limited by its low thermal conductivity. The fuel concept considered here is a...

  18. High Thermal Conductivity UO2-BeO Nulcear Fuel: Neutronic Performance Assessments and Overview of Fabrication 

    E-Print Network [OSTI]

    Naramore, Michael J

    2010-08-03T23:59:59.000Z

    The objective of this work was to evaluate a new high conductivity nuclear fuel form. Uranium dioxide (UO2) is a very effective nuclear fuel, but it’s performance is limited by its low thermal conductivity. The fuel concept considered here is a...

  19. Thermoelectric properties of ZnSb films grown by MOCVD

    SciTech Connect (OSTI)

    Venkatasubramanian, R.; Watko, E.; Colpitts, T.

    1997-07-01T23:59:59.000Z

    The thermoelectric properties of ZnSb films grown by metallorganic chemical vapor deposition (MOCVD) are reported. The growth conditions necessary to obtain stoichiometric ZnSb films and the effects of various growth parameters on the electrical conductivity and Seebeck coefficients of the films are described. The as-grown ZnSb films are p-type. It was observed that the thicker ZnSb films offer improved carrier mobilities and lower free-carrier concentration levels. The Seebeck coefficient of ZnSb films was found to rise rapidly at approximately 160 C. The thicker films, due to the lower doping levels, indicate higher Seebeck coefficients between 25 to 200 C. A short annealing of the ZnSb film at temperatures of {approximately}200 C results in reduced free-carrier level. Thermal conductivity measurements of ZnSb films using the 3-{omega} method are also presented.

  20. Thermoelectric characterization of suspended single silicon%3CU%2B2010%3Egermanium alloy nanowires.

    SciTech Connect (OSTI)

    Sullivan, John Patrick; Picraux, Samuel Thomas; Martinez, Julio Alberto; Swartzentruber, Brian Shoemaker

    2010-11-01T23:59:59.000Z

    The use of nanowires for thermoelectric energy generation has gained momentum in recent years as an approach to improve the figure of merit (ZT) due in part to larger phonon scattering at the boundary resulting in reduced thermal conductivity while electrical conductivity is not significantly affected. Silicon-germanium (SiGe) alloy nanowires are promising candidates to further reduce thermal conductivity by phonon scattering because bulk SiGe alloys already have thermal conductivity comparable to reported Si nanowires. In this work, we show that thermal and electrical conductivity can be measured for the same single nanowire eliminating the uncertainties in ZT estimation due to measuring the thermal conduction on one set of wires and the electrical conduction on another set. In order to do so, we use nanomanipulation to place vapor-liquid-solid boron-doped SiGe alloy nanowires on predefined surface structures. Furthermore, we developed a contact-annealing technique to achieve negligible electrical contact resistance for the placed nanowires that allows us, for the first time, to measure electrical and thermal properties on the same device. We observe that thermal conductivity for SiGe nanowires is dominated by alloy scattering for nanowires down to 100 nm in diameter between the temperature range 40-300 K. The estimated electronic contribution of the thermal conductivity as given by the Wiedemann-Franz relationship is about 1 order of magnitude smaller than the measured thermal conductivity which indicates that phonons carry a large portion of the heat even at such small dimensions.

  1. Investigation into the effect of heat treatment on the thermal conductivity of 3-D carbon/carbon fiber composites

    SciTech Connect (OSTI)

    Dinwiddie, R.B.; Burchell, T.D. (Oak Ridge National Lab., TN (USA)); Baker, C.F. (Fiber Materials, Inc., Biddeford, ME (USA))

    1991-01-01T23:59:59.000Z

    The material used in this study was a carbon-carbon fiber composite manufactured from precursor yarn and petroleum based pitch through a process of repetitive densification of a woven preform. The resultant high temperature-high strength material exhibits relatively high thermal conductivity and is thus of interest to the fusion energy, plasma materials interactions (PMI) and plasma facing components (PFC) communities. Carbon-carbon fiber composite manufacture involves two distinct processes, preform weaving and component densification. In this study three samples were subjected to an additional heat treatment of 2550, 2750 or 3000{degree}C at Oak Ridge National Laboratory (ORNL) subsequent to their fourth graphitization at 2400{degree}C. It should be noted that no effort was made to optimize the composite for thermal conductivity, but rather only to provide a material with which to evaluate the effect of the final heat treatment temperature on the thermal conductivity. The fiber is the primary source of heat conduction in the composite. Consequently, increasing the fiber volume fraction, and/or the fiber thermal conductivity is expected to increase the composite thermal conductivity. 3 refs., 1 fig.

  2. Method of making improved gas storage carbon with enhanced thermal conductivity

    DOE Patents [OSTI]

    Burchell, Timothy D. (Oak Ridge, TN); Rogers, Michael R. (Knoxville, TN)

    2002-11-05T23:59:59.000Z

    A method of making an adsorbent carbon fiber based monolith having improved methane gas storage capabilities is disclosed. Additionally, the monolithic nature of the storage carbon allows it to exhibit greater thermal conductivity than conventional granular activated carbon or powdered activated carbon storage beds. The storage of methane gas is achieved through the process of physical adsorption in the micropores that are developed in the structure of the adsorbent monolith. The disclosed monolith is capable of storing greater than 150 V/V of methane [i.e., >150 STP (101.325 KPa, 298K) volumes of methane per unit volume of storage vessel internal volume] at a pressure of 3.5 MPa (500 psi).

  3. On linearization and preconditioning for radiation diffusion coupled to material thermal conduction equations

    SciTech Connect (OSTI)

    Feng, Tao, E-mail: fengtao2@mail.ustc.edu.cn [School of Mathematical Sciences, University of Science and Technology of China, Hefei 230052 (China) [School of Mathematical Sciences, University of Science and Technology of China, Hefei 230052 (China); Graduate School of China Academy Engineering Physics, Beijing 100083 (China); An, Hengbin, E-mail: an_hengbin@iapcm.ac.cn [National Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China)] [National Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Yu, Xijun, E-mail: yuxj@iapcm.ac.cn [National Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China)] [National Key Laboratory of Computational Physics, Institute of Applied Physics and Computational Mathematics, Beijing 100094 (China); Li, Qin, E-mail: liqin@lsec.cc.ac.cn [Chinese Academy of Mathematics and Systems Science, Beijing 100190 (China)] [Chinese Academy of Mathematics and Systems Science, Beijing 100190 (China); Zhang, Rongpei, E-mail: zhangrongpei@163.com [Graduate School of China Academy Engineering Physics, Beijing 100083 (China)] [Graduate School of China Academy Engineering Physics, Beijing 100083 (China)

    2013-03-01T23:59:59.000Z

    Jacobian-free Newton–Krylov (JFNK) method is an effective algorithm for solving large scale nonlinear equations. One of the most important advantages of JFNK method is that there is no necessity to form and store the Jacobian matrix of the nonlinear system when JFNK method is employed. However, an approximation of the Jacobian is needed for the purpose of preconditioning. In this paper, JFNK method is employed to solve a class of non-equilibrium radiation diffusion coupled to material thermal conduction equations, and two preconditioners are designed by linearizing the equations in two methods. Numerical results show that the two preconditioning methods can improve the convergence behavior and efficiency of JFNK method.

  4. Thermoelectric heat exchange element

    DOE Patents [OSTI]

    Callas, James J. (Peoria, IL); Taher, Mahmoud A. (Peoria, IL)

    2007-08-14T23:59:59.000Z

    A thermoelectric heat exchange module includes a first substrate including a heat receptive side and a heat donative side and a series of undulatory pleats. The module may also include a thermoelectric material layer having a ZT value of 1.0 or more disposed on at least one of the heat receptive side and the heat donative side, and an electrical contact may be in electrical communication with the thermoelectric material layer.

  5. Review and comparison of nanofluid thermal conductivity and heat transfer enhancements.

    SciTech Connect (OSTI)

    Yu, W.; France, D. M.; Routbort, J. L.; Choi, S. U.S.; Energy Systems; Univ. of Illinois at Chicago; Korea Inst. of Energy Research

    2008-05-01T23:59:59.000Z

    This study provides a detailed literature review and an assessment of results of the research and development work forming the current status of nanofluid technology for heat transfer applications. Nanofluid technology is a relatively new field, and as such, the supporting studies are not extensive. Specifically, experimental results were reviewed in this study regarding the enhancement of the thermal conductivity and convective heat transfer of nanofluids relative to conventional heat transfer fluids, and assessments were made as to the state-of-the-art of verified parametric trends and magnitudes. Pertinent parameters of particle volume concentration, particle material, particle size, particle shape, base fluid material, temperature, additive, and acidity were considered individually, and experimental results from multiple research groups were used together when assessing results. To this end, published research results from many studies were recast using a common parameter to facilitate comparisons of data among research groups and to identify thermal property and heat transfer trends. The current state of knowledge is presented as well as areas where the data are presently inconclusive or conflicting. Heat transfer enhancement for available nanofluids is shown to be in the 15-40% range, with a few situations resulting in orders of magnitude enhancement.

  6. Thermal and Electric Conductivities of Coulomb Crystals in Neutron Stars and White Dwarfs

    E-Print Network [OSTI]

    D. A. Baiko; D. G. Yakovlev

    1996-04-28T23:59:59.000Z

    Thermal and electric conductivities are calculated for degenerate electrons scattered by phonons in a crystal made of atomic nuclei. The exact phonon spectrum and the Debye--Waller factor are taken into account. Monte Carlo calculations are performed for body-centered cubic (bcc) crystals made of C, O, Ne, Mg, Si, S, Ca, and Fe nuclei in the density range from $10^3$ to $10^{11}$ g cm$^{-3}$ at temperatures lower than the melting temperature but higher than the temperature at which the Umklapp processes begin to be "frozen out". A simplified method of calculation is proposed, which makes it possible to describe the results in terms of simple analytic expressions, to extend these expressions to any species of nucleus, and to consider face-centered cubic (fcc) crystals. The kinetic coefficients are shown to depend tangibly on the lattice type. The results are applicable to studies of heat transfer and evolution of the magnetic field in the cores of white dwarfs and in the crusts of neutron stars. The thermal drift of the magnetic field in the crust of a neutron star is discussed.

  7. Density dependence of the room temperature thermal conductivity of atomic layer deposition-grown amorphous alumina (Al{sub 2}O{sub 3})

    SciTech Connect (OSTI)

    Gorham, Caroline S.; Gaskins, John T.; Hopkins, Patrick E., E-mail: phopkins@virginia.edu [Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States); Parsons, Gregory N.; Losego, Mark D. [Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, North Carolina 27695 (United States)

    2014-06-23T23:59:59.000Z

    We report on the thermal conductivity of atomic layer deposition-grown amorphous alumina thin films as a function of atomic density. Using time domain thermoreflectance, we measure the thermal conductivity of the thin alumina films at room temperature. The thermal conductivities vary ?35% for a nearly 15% change in atomic density and are substrate independent. No density dependence of the longitudinal sound speeds is observed with picosecond acoustics. The density dependence of the thermal conductivity agrees well with a minimum limit to thermal conductivity model that is modified with a differential effective-medium approximation.

  8. Rare earth thermoelectrics

    SciTech Connect (OSTI)

    Mahan, G.D.

    1997-07-01T23:59:59.000Z

    A review is presented of the thermoelectric properties of rare earth compounds: A discussion is presented of the prospects for future improvements in the figure of merit.

  9. Vehicular Thermoelectric Applications

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Modules Available Energy in Engine Exhaust BMW Series 5 , Model Year 2011, 3.0 Liter Gasoline Engine w Thermoelectric Generator Funding Opportunity Announcement...

  10. Solar Thermoelectric Energy Conversion

    Broader source: Energy.gov [DOE]

    Efficiencies of different types of solar thermoelectric generators were predicted using theoretical modeling and validated with measurements using constructed prototypes under different solar intensities

  11. Concentrated Solar Thermoelectric Power

    Broader source: Energy.gov (indexed) [DOE]

    CONCENTRATING SOLAR POWER PROGRAM REVIEW 2013 Concentrated Solar Thermoelectric Power Principal Investigator: Prof. Gang Chen Massachusetts Institute of Technology Cambridge, MA...

  12. Thermal conduction by dark matter with velocity and momentum-dependent cross-sections

    E-Print Network [OSTI]

    Aaron C. Vincent; Pat Scott

    2014-04-23T23:59:59.000Z

    We use the formalism of Gould and Raffelt to compute the dimensionless thermal conduction coefficients for scattering of dark matter particles with standard model nucleons via cross-sections that depend on the relative velocity or momentum exchanged between particles. Motivated by models invoked to reconcile various recent results in direct detection, we explicitly compute the conduction coefficients $\\alpha$ and $\\kappa$ for cross-sections that go as $v_{\\rm rel}^2$, $v_{\\rm rel}^4$, $v_{\\rm rel}^{-2}$, $q^2$, $q^4$ and $q^{-2}$, where $v_{\\rm rel}$ is the relative DM-nucleus velocity and $q$ is the momentum transferred in the collision. We find that a $v_{\\rm rel}^{-2}$ dependence can significantly enhance energy transport from the inner solar core to the outer core. The same can true for any $q$-dependent coupling, if the dark matter mass lies within some specific range for each coupling. This effect can complement direct searches for dark matter; combining these results with state-of-the-art Solar simulations should greatly increase sensitivity to certain DM models. It also seems possible that the so-called Solar Abundance Problem could be resolved by enhanced energy transport in the solar core due to such velocity- or momentum-dependent scatterings.

  13. Comparison of Different Upscaling Methods for Predicting Thermal Conductivity of Complex Heterogeneous Materials System: Application on Nuclear Waste Forms

    SciTech Connect (OSTI)

    Li, Dongsheng; Sun, Xin; Khaleel, Mohammad A.

    2012-06-16T23:59:59.000Z

    To develop a strategy in thermal conductivity prediction of a complex heterogeneous materials system, loaded nuclear waste forms, the computational efficiency and accuracy of different upscaling methods have been evaluated. The effective thermal conductivity, obtained from microstructure information and local thermal conductivity of different components, is critical in predicting the life and performance of waste form during storage. Several methods, including the Taylor model, Sachs model, self-consistent model, and statistical upscaling method, were developed and implemented. Microstructure based finite element method (FEM) prediction results were used to as benchmark to determine the accuracy of the different upscaling methods. Micrographs from waste forms with varying waste loadings were used in the prediction of thermal conductivity in FEM and homogenization methods. Prediction results demonstrated that in term of efficiency, boundary models (e.g., Taylor model and Sachs model) are stronger than the self-consistent model, statistical upscaling method, and finite element method. However, when balancing computational efficiency and accuracy, statistical upscaling is a useful method in predicting effective thermal conductivity for nuclear waste forms.

  14. Measurement and characterization techniques for thermoelectric materials

    SciTech Connect (OSTI)

    Tritt, T.M.

    1997-07-01T23:59:59.000Z

    Characterization of thermoelectric materials can pose many problems. A temperature difference can be established across these materials as an electrical current is passed due to the Peltier effect. The thermopower of these materials is quite large and thus large thermal voltages can contribute to many of the measurements necessary to investigate these materials. This paper will discuss the chracterization techniques necessary to investigate these materials and provide an overview of some of the potential systematic errors which can arise. It will also discuss some of the corrections one needs to consider. This should provide an introduction to the characterization and measurement of thermoelectric materials and provide references for a more in depth discussion of the concepts. It should also serve as an indication of the care that must be taken while working with thermoelectric materials.

  15. Scalable Routes to Efficient Thermoelectric Materials

    E-Print Network [OSTI]

    Feser, Joseph Patrick

    2010-01-01T23:59:59.000Z

    P. D. Yang, "Enhanced thermoelectric performance of roughHigh efficiency thermoelectric materials consisting ofG. Chen, and Z. F. Ren, "High-thermoelectric performance of

  16. Holey Silicon as an Efficient Thermoelectric Material

    E-Print Network [OSTI]

    Tang, Jinyao

    2011-01-01T23:59:59.000Z

    Silicon as Efficient Thermoelectric Material Jinyao Tang 1,This work investigated the thermoelectric properties of thinat room temperature, the thermoelectric performance of HS is

  17. Thermoelectric Properties of Scaled Silicon Nanowires Using the s*-SO Atomistic Tight-Binding Model and Boltzmann

    E-Print Network [OSTI]

    1 Thermoelectric Properties of Scaled Silicon Nanowires Using the sp3 d5 s*-SO Atomistic Tight|kosina}@iue.tuwien.ac.at Abstract As a result of suppressed phonon conduction, large improvements of the thermoelectric figure, the Seebeck coefficient, and the thermoelectric power factor. We examine n-type nanowires of diameters of 3nm

  18. Thermoelectric and micro-Raman measurements of carrier density and mobility in heavily Si-doped GaN wires

    E-Print Network [OSTI]

    Boyer, Edmond

    Thermoelectric and micro-Raman measurements of carrier density and mobility in heavily Si-doped Ga (Received 19 July 2013; accepted 28 October 2013; published online 11 November 2013) Combined thermoelectric epitaxy (MOVPE). These highly conductive Si-doped GaN wires were studied by means of thermoelectrical

  19. Numerical investigation of CO{sub 2} emission and thermal stability of a convective and radiative stockpile of reactive material in a cylindrical pipe of variable thermal conductivity

    SciTech Connect (OSTI)

    Lebelo, Ramoshweu Solomon, E-mail: sollyl@vut.ac.za [Department of Mathematics, Vaal University of Technology, Private Bag X021, Vanderbijlpark, 1911 (South Africa)

    2014-10-24T23:59:59.000Z

    In this paper the CO{sub 2} emission and thermal stability in a long cylindrical pipe of combustible reactive material with variable thermal conductivity are investigated. It is assumed that the cylindrical pipe loses heat by both convection and radiation at the surface. The nonlinear differential equations governing the problem are tackled numerically using Runge-Kutta-Fehlberg method coupled with shooting technique method. The effects of various thermophysical parameters on the temperature and carbon dioxide fields, together with critical conditions for thermal ignition are illustrated and discussed quantitatively.

  20. Thermal conductivity of the electrode gap of a thermionic converter, filled with inert gases, at low pressures

    SciTech Connect (OSTI)

    Modin, V.A.; Nikolaev, Y.V.

    1985-11-01T23:59:59.000Z

    Experimental data is presented on the thermal conductivity of the electrode gap of a thermionic converter filled with He, Ar, and Xe in the pressure range 40--550 Pa. The need to account for the coefficients of thermal accommodation of the emitter-inert-gas-collector system in this range is shown. The accommodation coefficients for different temperature regimes are measured and expressions are obtained to calculate the heat flux transported by the inert gases in the electrode gap.

  1. Design of a steady state thermal conductivity measurement device for CNT RET polymer composites

    E-Print Network [OSTI]

    Louie, Brian Ming

    2011-01-01T23:59:59.000Z

    conductive particles along with CNTs in polymer composites.polymer composites. 2,12 The combination of highly conductive

  2. Experimental Study of Thermodiffusion and Thermoelectricity in Charged Colloids

    E-Print Network [OSTI]

    B. T. Huang; M. Roger; M. Bonetti; T. J. Salez; C. Wiertel-Gasquet; E. Dubois; R. Cabreira Gomes; G. Demouchy; G. Mériguet; V. Peyre; M. Kouyaté; C. L. Filomeno; J. Depeyrot; F. A. Tourinho; R. Perzynski; S. Nakamae

    2015-03-30T23:59:59.000Z

    The Seebeck and Soret coefficients of ionically stabilized suspension of maghemite nanoparticles in dimethyl sulfoxide are experimentally studied as a function of nanoparticle volume fraction. In the presence of a temperature gradient, the charged colloidal nanoparticles experience both thermal drift due to their interactions with the solvent molecules and electric forces proportional to the internal thermoelectric field. The resulting thermodiffusion of nanoparticles is observed through Forced Rayleigh scattering, while the thermoelectric field is accessed through voltage measurements in a thermocell. Both techniques provide independent estimates of nanoparticle's entropy of transfer as high as 75 meV/K. Such a property may be used to improve the thermoelectric coefficients in liquid thermocells.

  3. Thermoelectric characteristic of the rough InN/GaN core-shell nanowires

    SciTech Connect (OSTI)

    Wu, Chao-Wei; Wu, Yuh-Renn, E-mail: yrwu@ntu.edu.tw [Graduate Institute of Photonics and Optoelectronics and Department of Electrical Engineering, National Taiwan University, Taipei 10617, Taiwan (China)

    2014-09-14T23:59:59.000Z

    An analysis to model the thermoelectric (TE) effects of the rough InN/GaN core-shell nanowires (NWs) with wire diameter ranging from 25?nm to 100?nm is proposed. The elastic continuum model is employed to calculate the phonon dispersion relation curves and the related phonon group velocity. Within the framework of Boltzmann transport equations and relaxation time approximation, the electrical conductivity, Seebeck coefficient, electronic thermal conductivity, and the lattice thermal conductivity is obtained. Simulation results indicate that TE properties of the rough InN/GaN core-shell NWs are strongly affected by the surface roughness and the diameter of NWs. The optimized condition of the proposed rough InN/GaN core-shell TE NWs is studied in this paper and the highest ZT obtained in the calculation is 0.8598 at 300?K and 1.713 at 1000?K.

  4. Effective Thermal Conductivity of a Li{sub 2}TiO{sub 3} Pebble Bed for a DEMO Blanket

    SciTech Connect (OSTI)

    Hatano, T.; Enoeda, M.; Suzuki, S.; Kosaku, Y.; Akiba, M. [Japan Atomic Energy Research Institute (Japan)

    2003-07-15T23:59:59.000Z

    In development of the ceramic breeder blanket, the effective thermal conductivity of pebble beds is an important design parameter. For thermo-mechanical design of blanket, pebble beds were investigated used for Li{sub 2}TiO{sub 3} that was a candidate for tritium breeder. Li{sub 2}TiO{sub 3} pebble beds, whose size was 0.28-1.91 mm diameter, were measured on load under no neutron irradiation. The effective thermal conductivity was increased with load increasing was obtained.

  5. Evaluation of Thermal to Electrical Energy Conversion of High...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Thermal to Electrical Energy Conversion of High Temperature Skutterudite-Based Thermoelectric Modules Evaluation of Thermal to Electrical Energy Conversion of High Temperature...

  6. Thermoelectric energy converter for generation of electricity from low-grade heat

    DOE Patents [OSTI]

    Jayadev, T.S.; Benson, D.K.

    1980-05-27T23:59:59.000Z

    A thermoelectric energy conversion device which includes a plurality of thermoelectric elements is described. A hot liquid is supplied to one side of each element and a cold liquid is supplied to the other side of each element. The thermoelectric generator may be utilized to produce power from low-grade heat sources such as ocean thermal gradients, solar ponds, and low-grade geothermal resources. (WHK)

  7. A comparison of the values of thermal conductivity of a dry porous material determined by various laboratory methods

    E-Print Network [OSTI]

    Fluker, Billie J

    1953-01-01T23:59:59.000Z

    and Accepted Standazd Values of Rhombic Sulphur Therxml Conductivity with Temperature . ~ ~. . . . . . . . . 40 Introduction There are three possibilities of obtaining numerical data for thermal conductivity of porous materials One is by the use.... It uas also necessary that tbe material selected be such that the preparation of teat specimens could be completed in the laboratory uithout specialiaed technique. Hhambic sulphur uas selected for test since it embodied each of these features...

  8. Complex oxides useful for thermoelectric energy conversion

    DOE Patents [OSTI]

    Majumdar, Arunava (Orinda, CA); Ramesh, Ramamoorthy (Moraga, CA); Yu, Choongho (College Station, TX); Scullin, Matthew L. (Berkeley, CA); Huijben, Mark (Enschede, NL)

    2012-07-17T23:59:59.000Z

    The invention provides for a thermoelectric system comprising a substrate comprising a first complex oxide, wherein the substrate is optionally embedded with a second complex oxide. The thermoelectric system can be used for thermoelectric power generation or thermoelectric cooling.

  9. Measurement of Thermal Conductivity of PbTe Nanocrystal Coated Glass Fibers by the 3 Method

    E-Print Network [OSTI]

    Ruan, Xiulin

    using the self-heated 3 method particularly at low frequency. While prior 3 measurements on wire to measure the thermal properties of wire-like samples in the axial direction. These include the self-heating and electrical thermal sensing,6 pulsed laser-assisted thermal relaxation technique,7 and the technique

  10. Electrical and thermal conductivities of reduced graphene oxide/polystyrene Wonjun Park, Jiuning Hu, Luis A. Jauregui, Xiulin Ruan, and Yong P. Chen

    E-Print Network [OSTI]

    Chen, Yong P.

    conductive polymer composites are used as heat sinks for device packaging requiring a high thermalElectrical and thermal conductivities of reduced graphene oxide/polystyrene composites Wonjun Park. The electrical conductivity (r) of RGO/PS composites with different RGO concentrations at room temperature shows

  11. Proactive Strategies for Designing Thermoelectric Materials for...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    More Documents & Publications Proactive Strategies for Designing Thermoelectric Materials for Power Generation Thermoelectric Couple Demonstration of (In,...

  12. Trends in Thermoelectric Properties with Nanostructure: Ferecrystals...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Thermoelectric Properties with Nanostructure: Ferecrystals with Designed Nanoarchitecture Trends in Thermoelectric Properties with Nanostructure: Ferecrystals with Designed...

  13. Proactive Strategies for Designing Thermoelectric Materials for...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    More Documents & Publications Proactive Strategies for Designing Thermoelectric Materials for Power Generation Proactive Strategies for Designing Thermoelectric...

  14. The Industrialization of Thermoelectric Power Generation Technology...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    The Industrialization of Thermoelectric Power Generation Technology The Industrialization of Thermoelectric Power Generation Technology Presents module and system requirements for...

  15. Ferecrystals: Thermoelectric Materials Poised Between the Crystalline...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Ferecrystals: Thermoelectric Materials Poised Between the Crystalline and Amorphous States Ferecrystals: Thermoelectric Materials Poised Between the Crystalline and Amorphous...

  16. Engineering and Materials for Automotive Thermoelectric Applications...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    and Materials for Automotive Thermoelectric Applications Engineering and Materials for Automotive Thermoelectric Applications Design and optimization of TE exhaust generator,...

  17. Skutterudite Thermoelectric Generator For Automotive Waste Heat...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Skutterudite Thermoelectric Generator For Automotive Waste Heat Recovery Skutterudite Thermoelectric Generator For Automotive Waste Heat Recovery Skutterudite TE modules were...

  18. Novel Nanostructured Interface Solution for Automotive Thermoelectric...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Nanostructured Interface Solution for Automotive Thermoelectric Modules Application Novel Nanostructured Interface Solution for Automotive Thermoelectric Modules Application...

  19. Measurements of the apparent thermal conductivity of multi-layer insulation between 20 K and 90 K

    SciTech Connect (OSTI)

    Hurd, Joseph A.; Van Sciver, Steven W. [National High Magnetic Field Laboratory Tallahassee, FL 32310 USA and FAMU-FSU College of Engineering, Department of M.E., Tallahassee, FL 32310 (United States)

    2014-01-29T23:59:59.000Z

    NASA has the need to efficiently store cryogenic propellants in space for long periods of time. One method to improve storage efficiency is to use multi-layer insulation (MLI), a technique that minimizes the boiling rate due to radiation heat transfer. Typically, the thermal performance of MLI is determined by measuring the rate of evaporation of liquid nitrogen from a calibrated cryostat. The main limitation with this method is that testing conditions are restricted by the boiling temperature of the LN{sub 2}, which may not match the requirements of the application. The Multi-Layer Insulation Thermal Conductivity Experiment (MIKE) at the National High Magnetic Field Laboratory is capable of measuring the effective thermal conductivity of MLI at variable boundary temperatures. MIKE uses cryo-refrigerators to control boundary temperatures in the calorimeter and a calibrated thermal link to measure the heat load. To make the measurements requested by NASA, MIKE needed to be recalibrated for the 20 K to 90 K range. Also, due to the expectation of a lower heat transfer rate, the heat load support rod material was changed to one with a lower thermal conductivity to ensure the temperature difference seen on the cold rod could be measurable at the estimated heat load. Presented are the alterations to MIKE including calibration data and heat load measurements on new load-bearing MLI supplied by NASA.

  20. Effective Thermal Conductivity of Soda-Lime Silicate Glassmelts with Different Iron Contents Between 1100C and 1500C

    E-Print Network [OSTI]

    Pilon, Laurent

    Effective Thermal Conductivity of Soda-Lime Silicate Glassmelts with Different Iron Contents collected for soda- lime silicate glasses with iron content ranging from 0.008 to 1.1 wt% and temperatures, refractory walls wear more rapidly for clear glassmelts compared with colored ones.1 Soda-lime silicate glass

  1. Magnetic enhancement of thermal conductivity in coppercarbon nanotube composites produced by electroless plating, freeze drying, and spark plasma sintering

    E-Print Network [OSTI]

    Meyers, Marc A.

    by electroless plating, freeze drying, and spark plasma sintering Evan Khaleghi a, , Milton Torikachvili b , Marc Available online 9 April 2012 Keywords: Magnetic Carbon nanotube Spark plasma sintering Thermal conductivity and freeze-drying for green processing, and spark plasma sintering for densification. A magnetic field of 1

  2. E. In Situ Polymerization of Cyclic Butylene Terephthalate(CBT) Oligomers with Conductive fillers for Thermal Management

    E-Print Network [OSTI]

    Harmon, Julie P.

    copolymers with Thermal conductivity Composites This research is funded by Honeywell Corporation and the Florida High Tech Corridor. NOTE: Honeywell and Julie Harmon have signed an agreement with Cyclics Corp; these materials exhibit an intrinsic fiber TC as high as 913 W/mK (51). Earlier work with Honeywell focused

  3. The thermoelectric process

    SciTech Connect (OSTI)

    Vining, C.B.

    1997-07-01T23:59:59.000Z

    The efficiency of thermoelectric technology today is limited by the properties of available thermoelectric materials and a wide variety of new approaches to developing better materials have recently been suggested. The key goal is to find a material with a large ZT, the dimensionless thermoelectric figure of merit. However, if an analogy is drawn between thermoelectric technology and gas-cycle engines then selecting different materials for the thermoelements is analogous to selecting a different working gas for the mechanical engine. And an attempt to improve ZT is analogous to an attempt to improve certain thermodynamic properties of the working-gas. An alternative approach is to focus on the thermoelectric process itself (rather than on ZT), which is analogous to considering alternate cycles such as Stirling vs. Brayton vs. Rankine etc., rather than merely considering alternative gases. Focusing on the process is a radically different approach compared to previous studies focusing on ZT. Aspects of the thermoelectric process and alternative approaches to efficient thermoelectric conversion are discussed.

  4. Significant enhancement in thermoelectric properties of polycrystalline Pr-doped SrTiO{sub 3??} ceramics originating from nonuniform distribution of Pr dopants

    SciTech Connect (OSTI)

    Dehkordi, Arash Mehdizadeh, E-mail: amehdiz@g.clemson.edu [Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634 (United States); Bhattacharya, Sriparna; He, Jian [Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634 (United States); Alshareef, Husam N. [Materials Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900 (Saudi Arabia); Tritt, Terry M., E-mail: ttritt@clemson.edu [Department of Materials Science and Engineering, Clemson University, Clemson, South Carolina 29634 (United States); Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634 (United States)

    2014-05-12T23:59:59.000Z

    Recently, we have reported a significant enhancement (>70% at 500?°C) in the thermoelectric power factor (PF) of bulk polycrystalline Pr-doped SrTiO{sub 3} ceramics employing a novel synthesis strategy which led to the highest ever reported values of PF among doped polycrystalline SrTiO{sub 3}. It was found that the formation of Pr-rich grain boundary regions gives rise to an enhancement in carrier mobility. In this Letter, we investigate the electronic and thermal transport in Sr{sub 1?x}Pr{sub x}TiO{sub 3} ceramics in order to determine the optimum doping concentration and to evaluate the overall thermoelectric performance. Simultaneous enhancement in the thermoelectric power factor and reduction in thermal conductivity in these samples resulted in more than 30% improvement in the dimensionless thermoelectric figure of merit (ZT) for the whole temperature range over all previously reported maximum values. Maximum ZT value of 0.35 was obtained at 500?°C.

  5. Thermal Energy Harvesting with Thermoelectrics for Self-powered Sensors: With Applications to Implantable Medical Devices, Body Sensor Networks and Aging in Place

    E-Print Network [OSTI]

    Chen, Alic

    2011-01-01T23:59:59.000Z

    models for conductive polymer composites,” Journal ofConductive Liquid Crystal Polymer Based Resins,” Journal of CompositeConductive composites past, present, and future,” Polymer

  6. Hyper-resistivity and electron thermal conductivity due to destroyed magnetic surfaces in axisymmetric plasma equilibria

    SciTech Connect (OSTI)

    Weening, R. H. [Department of Radiologic Sciences, Thomas Jefferson University, 901 Walnut Street, Philadelphia, Pennsylvania 19107-5233 (United States)

    2012-06-15T23:59:59.000Z

    In order to model the effects of small-scale current-driven magnetic fluctuations in a mean-field theoretical description of a large-scale plasma magnetic field B(x,t), a space and time dependent hyper-resistivity {Lambda}(x,t) can be incorporated into the Ohm's law for the parallel electric field E Dot-Operator B. Using Boozer coordinates, a theoretical method is presented that allows for a determination of the hyper-resistivity {Lambda}({psi}) functional dependence on the toroidal magnetic flux {psi} for arbitrary experimental steady-state Grad-Shafranov axisymmetric plasma equilibria, if values are given for the parallel plasma resistivity {eta}({psi}) and the local distribution of any auxiliary plasma current. Heat transport in regions of plasma magnetic surfaces destroyed by resistive tearing modes can then be modeled by an electron thermal conductivity k{sub e}({psi})=({epsilon}{sub 0}{sup 2}m{sub e}/e{sup 2}){Lambda}({psi}), where e and m{sub e} are the electron charge and mass, respectively, while {epsilon}{sub 0} is the permittivity of free space. An important result obtained for axisymmetric plasma equilibria is that the {psi}{psi}-component of the metric tensor of Boozer coordinates is given by the relation g{sup {psi}{psi}}({psi}){identical_to}{nabla}{psi} Dot-Operator {nabla}{psi}=[{mu}{sub 0}G({psi})][{mu}{sub 0}I({psi})]/{iota}({psi}), with {mu}{sub 0} the permeability of free space, G({psi}) the poloidal current outside a magnetic surface, I({psi}) the toroidal current inside a magnetic surface, and {iota}({psi}) the rotational transform.

  7. Thermal conductivity of the quark matter for the SU(2) light-flavor sector

    E-Print Network [OSTI]

    Seung-il Nam

    2015-03-04T23:59:59.000Z

    We investigate the thermal conductivity ($\\kappa$) of the quark matter at finite quark chemical potential $(\\mu)$ and temperature $(T)$, employing the Green-Kubo formula, for the SU(2) light-flavor sector with the finite current-quark mass $m=5$ MeV. As a theoretical framework, we construct an effective thermodynamic potential from the $(\\mu,T)$-modified liquid-instanton model (mLIM). Note that all the relevant model parameters are designated as functions of $T$, using the trivial-holonomy caloron solution. By solving the self-consistent equation of mLIM, we acquire the constituent-quark mass $M_0$ as a function of $T$ and $\\mu$, satisfying the universal-class patterns of the chiral phase transition. From the numerical results for $\\kappa$, we observe that there emerges a peak at $\\mu\\approx200$ MeV for the low-$T$ region, i.e. $T\\lesssim100$ MeV. As $T$ increase over $T\\approx100$ MeV, the curve for $\\kappa$ is almost saturated as a function of $T$ in the order of $\\sim10^{-1}\\,\\mathrm{GeV}^2$, and grows with respect to $\\mu$ smoothly. At the normal nuclear-matter density $\\rho_0=0.17\\,\\mathrm{fm}^{-3}$, $\\kappa$ shows its maximum $6.22\\,\\mathrm{GeV}^2$ at $T\\approx10$ MeV, then decreases exponentially down to $\\kappa\\approx0.2\\,\\mathrm{GeV}^2$. We also compute the ratio of $\\kappa$ and the entropy density, i.e. $\\kappa/s$ as a function of $(\\mu,T)$ which is a monotonically decreasing function for a wide range of $T$, then approaches a lower bound at very high $T$: $\\kappa/s_\\mathrm{min}\\gtrsim0.3\\,\\mathrm{GeV}^{-1}$ in the vicinity of $\\mu=0$.

  8. Method and apparatus for producing a carbon based foam article having a desired thermal-conductivity gradient

    DOE Patents [OSTI]

    Klett, James W. (Knoxville, TN) [Knoxville, TN; Cameron, Christopher Stan (Sanford, NC) [Sanford, NC

    2010-03-02T23:59:59.000Z

    A carbon based foam article is made by heating the surface of a carbon foam block to a temperature above its graphitizing temperature, which is the temperature sufficient to graphitize the carbon foam. In one embodiment, the surface is heated with infrared pulses until heat is transferred from the surface into the core of the foam article such that the graphitizing temperature penetrates into the core to a desired depth below the surface. The graphitizing temperature is maintained for a time sufficient to substantially entirely graphitize the portion of the foam article from the surface to the desired depth below the surface. Thus, the foam article is an integral monolithic material that has a desired conductivity gradient with a relatively high thermal conductivity in the portion of the core that was graphitized and a relatively low thermal conductivity in the remaining portion of the foam article.

  9. Thermal Conductivity Enhancement of High Temperature Phase Change Materials for Concentrating Solar Power Plant Applications

    E-Print Network [OSTI]

    Roshandell, Melina

    2013-01-01T23:59:59.000Z

    batteries. Solar Water Heater Solar water heater is becomingSolar Water Heater heaters, thermal protection for electronics, spacecrafts, and solar

  10. Energy harvesting using a thermoelectric material

    DOE Patents [OSTI]

    Nersessian, Nersesse (Van Nuys, CA); Carman, Gregory P. (Los Angeles, CA); Radousky, Harry B. (San Leandro, CA)

    2008-07-08T23:59:59.000Z

    A novel energy harvesting system and method utilizing a thermoelectric having a material exhibiting a large thermally induced strain (TIS) due to a phase transformation and a material exhibiting a stress induced electric field is introduced. A material that exhibits such a phase transformation exhibits a large increase in the coefficient of thermal expansion over an incremental temperature range (typically several degrees Kelvin). When such a material is arranged in a geometric configuration, such as, for a example, a laminate with a material that exhibits a stress induced electric field (e.g. a piezoelectric material) the thermally induced strain is converted to an electric field.

  11. System and method to improve the power output and longevity of a radioisotope thermoelectric generator

    SciTech Connect (OSTI)

    Mowery, A.L. Jr.

    1993-09-21T23:59:59.000Z

    By using the helium generated by the alpha emissions of a thermoelectric generator during space travel for cooling, the thermal degradation of the thermoelectric generator can be slowed. Slowing degradation allows missions to be longer with little additional expense or payload. 1 figures.

  12. System and method to improve the power output and longetivity of a radioisotope thermoelectric generator

    SciTech Connect (OSTI)

    Mowery, A.L. Jr.

    1992-12-31T23:59:59.000Z

    By using the helium generated by the alpha emissions of a thermoelectric generator during space travel for cooling the thermal degradation of the thermoelectric generator can be slowed. Slowing degradation allows missions to be longer with little additional expense or payload.

  13. System and method to improve the power output and longetivity of a radioisotope thermoelectric generator

    DOE Patents [OSTI]

    Mowery, Jr., Alfred L. (Potomac, MD)

    1993-01-01T23:59:59.000Z

    By using the helium generated by the alpha emissions of a thermoelectric generator during space travel for cooling, the thermal degradation of the thermoelectric generator can be slowed. Slowing degradation allows missions to be longer with little additional expense or payload.

  14. Bipolar thermoelectric devices

    E-Print Network [OSTI]

    Pipe, Kevin P. (Kevin Patrick), 1976-

    2004-01-01T23:59:59.000Z

    The work presented here is a theoretical and experimental study of heat production and transport in bipolar electrical devices, with detailed treatment of thermoelectric effects. Both homojunction and heterojunction devices ...

  15. Thermoelectric transport in superlattices

    SciTech Connect (OSTI)

    Reinecke, T.L.; Broido, D.A.

    1997-07-01T23:59:59.000Z

    The thermoelectric transport properties of superlattices have been studied using an exact solution of the Boltzmann equation. The role of heat transport along the barrier layers, of carrier tunneling through the barriers, of valley degeneracy and of the well width and energy dependences of the carrier-phonon scattering rates on the thermoelectric figure of merit are given. Calculations are given for Bi{sub 2}Te{sub 3} and for PbTe, and the results of recent experiments are discussed.

  16. A boron nitride nanotube peapod thermal rectifier

    SciTech Connect (OSTI)

    Loh, G. C., E-mail: jgloh@mtu.edu [Department of Physics, Michigan Technological University, Houghton, Michigan 49931 (United States); Institute of High Performance Computing, 1 Fusionopolis Way, #16-16 Connexis, Singapore 138632 (Singapore); Baillargeat, D. [CNRS-International-NTU-Thales Research Alliance (CINTRA), 50 Nanyang Drive, Singapore 637553 (Singapore)

    2014-06-28T23:59:59.000Z

    The precise guidance of heat from one specific location to another is paramount in many industrial and commercial applications, including thermal management and thermoelectric generation. One of the cardinal requirements is a preferential conduction of thermal energy, also known as thermal rectification, in the materials. This study introduces a novel nanomaterial for rectifying heat—the boron nitride nanotube peapod thermal rectifier. Classical non-equilibrium molecular dynamics simulations are performed on this nanomaterial, and interestingly, the strength of the rectification phenomenon is dissimilar at different operating temperatures. This is due to the contingence of the thermal flux on the conductance at the localized region around the scatterer, which varies with temperature. The rectification performance of the peapod rectifier is inherently dependent on its asymmetry. Last but not least, the favourable rectifying direction in the nanomaterial is established.

  17. Microstructure changes and thermal conductivity reduction in UO2 following 3.9 MeV He2+ ion irradiation

    SciTech Connect (OSTI)

    Janne Pakrinen; Marat Khafizov; Lingfeng He; Chris Wetland; Jian Gan; Andrew T. Nelson; David H Hurley; Anter El-Azab; Todd R Allen

    2014-11-01T23:59:59.000Z

    The microstructural changes and associated effects on thermal conductivity were examined in UO2 after irradiation using 3.9 MeV He2+ ions. Lattice expansion of UO2 was observed in x-ray diffraction after ion irradiation up to 5×1016 He2+/cm2 at low-temperature (< 200 °C). Transmission electron microscopy (TEM) showed homogenous irradiation damage across an 8 µm thick plateau region, which consisted of small dislocation loops accompanied by dislocation segments. Dome-shaped blisters were observed at the peak damage region (depth around 8.5 µm) in the sample subjected to 5×1016 He2+/cm2, the highest fluence reached, while similar features were not detected at 9×1015 He2+/cm2. Laser-based thermo-reflectance measurements showed that the thermal conductivity for the irradiated layer decreased about 55 % for the high fluence sample and 35% for the low fluence sample as compared to an un-irradiated reference sample. Detailed analysis for the thermal conductivity indicated that the conductivity reduction was caused by the irradiation induced point defects.

  18. Thermal conductivity of the electrode gap of a therminonic converter, filled with inert gases, at low pressures

    SciTech Connect (OSTI)

    Modin, V.A.; Nikolaev, Y.V.

    1986-05-01T23:59:59.000Z

    This paper presents experimental data on the thermal conductivity of the electrode gap of a thermionic converter filled with He, Ar, and Xe in the pessure range 40-550 Pa. The need to account for the coefficients of thermal accomodation of the emitter-inert-gas-collector system in this range is shown. The accomodation coefficients for different temperature regimes are measured and expressions are obtained to calculate the heat flux transported by the inert gases in the electrode gap. A diagram of the experimental thermionic converter is shown.

  19. In-line thermoelectric module

    DOE Patents [OSTI]

    Pento, Robert (Algonquin, IL); Marks, James E. (Glenville, NY); Staffanson, Clifford D. (S. Glens Falls, NY)

    2000-01-01T23:59:59.000Z

    A thermoelectric module with a plurality of electricity generating units each having a first end and a second end, the units being arranged first end to second end along an in-line axis. Each unit includes first and second elements each made of a thermoelectric material, an electrically conductive hot member arranged to heat one side of the first element, and an electrically conductive cold member arranged to cool another side of the first element and to cool one side of the second element. The hot member, the first element, the cold member and the second element are supported in a fixture, are electrically connected respectively to provide an electricity generating unit, and are arranged respectively in positions along the in-line axis. The individual components of each generating unit and the respective generating units are clamped in their in-line positions by a loading bolt at one end of the fixture and a stop wall at the other end of the fixture. The hot members may have a T-shape and the cold members an hourglass shape to facilitate heat transfer. The direction of heat transfer through the hot members may be perpendicular to the direction of heat transfer through the cold members, and both of these heat transfer directions may be perpendicular to the direction of current flow through the module.

  20. Studies of non-diffusive heat conduction through spatially periodic and time-harmonic thermal excitations

    E-Print Network [OSTI]

    Collins, Kimberlee C. (Kimberlee Chiyoko)

    2015-01-01T23:59:59.000Z

    Studies of non-diffusive heat conduction provide insight into the fundamentals of heat transport in condensed matter. The mean free paths (MFPs) of phonons that are most important for conducting heat are well represented ...

  1. Estimation of composite thermal conductivity of a heterogeneous methane hydrate sample using iTOUGH2

    E-Print Network [OSTI]

    Gupta, Arvind; Kneafsey, Timothy J.; Moridis, George J.; Seol, Yongkoo; Kowalsky, Michael B.; Sloan Jr., E.D.

    2006-01-01T23:59:59.000Z

    International Conference on Gas Hydrates, Trondheim, Norway,Challenges for the future/gas hydrates, NYAS 912, 304, 2000.C. , Thermal state of the gas hydrate reservoir, natural gas

  2. Modeling thermal conductivity in UO2 with BeO additions as a function of microstructure

    E-Print Network [OSTI]

    direction. Ó 2009 Elsevier B.V. All rights reserved. 1. Introduction Uranium dioxide (UO2) is the most gradients which affect heat removal and overall reactor performance. These thermal gradients strongly

  3. The high conductivity of iron and thermal evolution of the Earth's core Hitoshi Gomi a,

    E-Print Network [OSTI]

    with secular cooling (along with possible radioactive heating) and buoy- ant release of incompatible light, if thermal buoyancy alone drives convection, then the power for maintaining a geodynamo must be in excess

  4. Critical evaluation of anomalous thermal conductivity and convective heat transfer enhancement in nanofluids

    E-Print Network [OSTI]

    Prabhat, Naveen

    2010-01-01T23:59:59.000Z

    While robust progress has been made towards the practical use of nanofluids, uncertainties remain concerning the fundamental effects of nanoparticles on key thermo-physical properties. Nanofluids have higher thermal ...

  5. Thermal conductivity of single-walled carbon nanotubes Alexander V. Savin,1,2 Bambi Hu,3,4 and Yuri S. Kivshar1

    E-Print Network [OSTI]

    Thermal conductivity of single-walled carbon nanotubes Alexander V. Savin,1,2 Bambi Hu,3,4 and Yuri for Nonlinear Studies, Hong Kong Baptist University, Hong Kong, China 4 Department of Physics, University 2009; published 30 November 2009 We study numerically the thermal conductivity of single-walled carbon

  6. JOM, February 2013, Volume 65, Issue 2, pp 234-245 234 A Review of Thermal Conductivity of Polymer Matrix Syntactic Foams Effect of Hollow Particle Wall

    E-Print Network [OSTI]

    Gupta, Nikhil

    JOM, February 2013, Volume 65, Issue 2, pp 234-245 234 A Review of Thermal Conductivity of Polymer compositions of syntactic foams. Basic understating of the relationship between thermal conductivity Introduction Hollow particle filled polymer matrix composites, called syntactic foams, are used in weight

  7. The role of straining and morphology in thermal conductivity of a set of SiGe superlattices and biomimetic SiGe nanocomposites

    E-Print Network [OSTI]

    Tomar, Vikas

    The role of straining and morphology in thermal conductivity of a set of Si­Ge superlattices and biomimetic Si­Ge nanocomposites This article has been downloaded from IOPscience. Please scroll down to see and morphology in thermal conductivity of a set of Si­Ge superlattices and biomimetic Si­Ge nanocomposites Vikas

  8. The thermal conductivity of amorphous Ce1-xAlx alloys between 1.5 and 350 K

    E-Print Network [OSTI]

    Paris-Sud XI, Université de

    Al alloys as a function of temperature. For five alloys with an aluminium concentration increasing from 12L-801 The thermal conductivity of amorphous Ce1-xAlx alloys between 1.5 and 350 K A. Guessous and J'alliages amorphes de CeAl. Pour 5 alliages dont la teneur en aluminium varie de 12 at. % à 86 at. %, nous n

  9. An optimal guarding scheme for thermal conductivity measurement using a guarded cut-bar technique, part 1 experimental study

    SciTech Connect (OSTI)

    Changhu Xing [Utah State Univ., Logan, UT (United States). Dept. of Mechanical and Aerospace Engineering; Colby Jensen [Utah State Univ., Logan, UT (United States). Dept. of Mechanical and Aerospace Engineering; Charles Folsom [Utah State Univ., Logan, UT (United States). Dept. of Mechanical and Aerospace Engineering; Heng Ban [Utah State Univ., Logan, UT (United States). Dept. of Mechanical and Aerospace Engineering; Douglas W. Marshall [Idaho National Laboratory (INL), Idaho Falls, ID (United States)

    2014-01-01T23:59:59.000Z

    In the guarded cut-bar technique, a guard surrounding the measured sample and reference (meter) bars is temperature controlled to carefully regulate heat losses from the sample and reference bars. Guarding is typically carried out by matching the temperature profiles between the guard and the test stack of sample and meter bars. Problems arise in matching the profiles, especially when the thermal conductivitiesof the meter bars and of the sample differ, as is usually the case. In a previous numerical study, the applied guarding condition (guard temperature profile) was found to be an important factor in measurement accuracy. Different from the linear-matched or isothermal schemes recommended in literature, the optimal guarding condition is dependent on the system geometry and thermal conductivity ratio of sample to meter bar. To validate the numerical results, an experimental study was performed to investigate the resulting error under different guarding conditions using stainless steel 304 as both the sample and meter bars. The optimal guarding condition was further verified on a certified reference material, pyroceram 9606, and 99.95% pure iron whose thermal conductivities are much smaller and much larger, respectively, than that of the stainless steel meter bars. Additionally, measurements are performed using three different inert gases to show the effect of the insulation effective thermal conductivity on measurement error, revealing low conductivity, argon gas, gives the lowest error sensitivity when deviating from the optimal condition. The result of this study provides a general guideline for the specific measurement method and for methods requiring optimal guarding or insulation.

  10. Lunar Nuclear Power Plant With Solid Core Reactor, Heatpipes and Thermoelectric Conversion

    SciTech Connect (OSTI)

    Sayre, Edwin D. [Engineering Consultant, 218 Brooke Acres Drive, Los Gatos, CA 95032 (United States); Ring, Peter J. [Advanced Methods and Materials, 1190 Mountain View-Alviso Rd. Suite P, Sunnyvale, CA 94089 (United States); Brown, Neil [Engineering Consultant, 5134 Cordoy Lane, San Jose, CA 95124 (United States); Elsner, Norbert B.; Bass, John C. [Hi-Z Technology, Inc., 7606 Miramar Rd. Suite 7400, San Diego, CA 92126 (United States)

    2008-01-21T23:59:59.000Z

    This is a lunar nuclear power plant with the advantages of minimum mass, with no moving parts, no pumped liquid coolant, a solid metal rugged core, with no single point of failure. The electrical output is 100 kilowatts with a 500 kilowatt thermal reactor. The thermoelectric converters surround the potassium heatpipes from the core and water heatpipes surround the converter and connect to the radiator. The solid core reactor is made from HT9 alloy. The fuel is uranium oxide with 90% enrichment. The thermoelectric converter is bonded to the outside of the 1.10 inch ID heat pipe and is 30 inches long. The thermoelectric couple is Si/SiGe-Si/SiC Quantum Well with over 20% efficiency with an 890 K hot side and a 490 K cold side and produces 625 Watts. 176 converters produce 110 kWe. With less than 10% loss in controls this yields 100 kWe for use. The cylindrical thermoelectric converter is designed and fabricated by HIPing to keep brittle materials in compression and to ensure conductivity. The solid core is fabricated by machining the heatpipe tubes with 6 grooves that are diffusion bonded together by HIPing to form the fuel tubes. The maximum temperature of the heat pipes is 940 K and the return flow temperature is 890 K. The reactor core is hexagonal shaped, 61 cm. wide and 76.2 cm high with 12 rotating control drums surrounding it. There is shielding to protect components and human habitation. The radiator is daisy shaped at 45 degrees with each petal 5.5 meters long. The design life is ten years.

  11. A Correction Scheme for Thermal Conductivity Measurement Using the Comparative Cut-bar Technique Based on a 3D Numerical Simulation

    SciTech Connect (OSTI)

    Douglas W. Marshall; Changhu Xing; Charles Folsom; Colby Jensen; Heng Ban

    2014-05-01T23:59:59.000Z

    As an important factor affecting the accuracy of the thermal conductivity measurement, systematic (bias) error in the guarded comparative axial heat flow (cut-bar) method was mostly neglected by previous researches. This bias is due primarily to the thermal conductivity mismatch between sample and meter bars (reference), which is common for a sample of unknown thermal conductivity. A correction scheme, based on a finite element simulation of the measurement system, was proposed to reduce the magnitude of the overall measurement uncertainty. This scheme was experimentally validated by applying corrections on four types of sample measurements in which the specimen thermal conductivity is much smaller, slightly smaller, equal and much larger than that of the meter bar. As an alternative to the optimum guarding technique proposed before, the correction scheme can be used to minimize uncertainty contribution from the measurement system with non-optimal guarding conditions. It is especially necessary for large thermal conductivity mismatches between sample and meter bars.

  12. Self-templated synthesis and thermal conductivity investigation for ultrathin perovskite oxide nanowires

    E-Print Network [OSTI]

    Ruan, Xiulin

    conductivity of the bulk pellet made by compressing nanowire powder using spark plasma sintering shows a 64 conductivity of the bulk pellet fabricated by compressing these SrTiO3 nanowire powder using spark plasma sintering can be reduced by 64% at 1000 K. The self-templated synthesis approach involves two steps that can

  13. Thermal conductance of solid-liquid interfaces Scott Huxtable, Zhenbin Ge, David G. Cahill

    E-Print Network [OSTI]

    Braun, Paul

    on temperature of thetemperature of the nanotube · Assume heat capacity is comparable to graphitegraphite of the conductance? "heat capacity G" vs. "heat conduction G" #12;Comparisons between experiment and simulation capacity to convert time constant to G. For long tubes: [K] CFor long tubes: G = 22 MW m-2 K-1 100-T(liquid

  14. The Electrodeposition of PbTe Nanowires for Thermoelectric Applications

    E-Print Network [OSTI]

    Hillman, Peter

    2012-01-01T23:59:59.000Z

    of thermoelectrics. Radioisotope Thermoelectric Generatorthermoelectric generators use radiation from the sun instead of a radioisotope

  15. High thermoelectric performance BiSbTe alloy with unique low-dimensional structure

    SciTech Connect (OSTI)

    Xie Wenjie [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634-0978 (United States); Tang Xinfeng; Yan Yonggao; Zhang Qingjie [State Key Laboratory of Advanced Technology for Materials Synthesis and Processing, Wuhan University of Technology, Wuhan 430070 (China); Tritt, Terry M. [Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29634-0978 (United States)

    2009-06-01T23:59:59.000Z

    We report a detailed description of an innovative route of a melt spinning (MS) technique combined with a subsequent spark plasma sintering process in order to obtain high performance p-type Bi{sub 0.52}Sb{sub 1.48}Te{sub 3} bulk material, which possesses a unique low-dimensional structure. The unique structure consists of an amorphous structure, 5-15 nm fine nanocrystalline regions, and coherent interfaces between the resulting nanocrystalline regions. Measurements of the thermopower, electrical conductivity, and thermal conductivity have been performed over a range of temperature of 300-400 K. We found that MS technique can give us considerable control over the resulting nanostructure with good thermal stability during the temperature range of 300-400 K and this unique structure can effectively adjust the transport of phonons and electrons, in a manner such that it is beneficial to the overall thermoelectric performance of the material, primarily a reduction in the lattice thermal conductivity. Subsequently, this results in a maximum figure of merit ZT value of 1.56 at 300 K for p-type Bi{sub 0.52}Sb{sub 1.48}Te{sub 3} bulk material. This ZT value is over a 50% improvement of that of the state of the art commercial Bi{sub 2}Te{sub 3} materials. We also report results of thermal cycling of this material for over one hundred cycles between 300-400 K. Our work offers an innovative route for developing high performance bismuth telluride based alloys and devices, which have even broader prospects for commercial applications. This technique may also be applicable to other thermoelectric materials.

  16. Modeling and characterization of thermoelectric properties of SiGe nanocomposites

    E-Print Network [OSTI]

    Lee, Hohyun, 1978-

    2009-01-01T23:59:59.000Z

    Direct energy conversion between thermal and electrical energy based on thermoelectric effects is attractive for potential applications in waste heat recovery and environmentally-friendly refrigeration. The energy conversion ...

  17. ANALYTIC CRITERIA FOR THE MECHANICAL AND THERMAL STABILITY OF MAGNETIC STARS WITH FINITE ELECTRICAL CONDUCTIVITY

    E-Print Network [OSTI]

    ANALYTIC CRITERIA FOR THE MECHANICAL AND THERMAL STABILITY OF MAGNETIC STARS WITH FINITE ELECTRICAL in the envelope. This physical complication also affects the interpretation of the RR Lyrae stars and other cool stars, the destabilized envelope is mostly radiative and convection probably plays only a small role

  18. Effect of sintering in ball-milled K{sub 2}Bi{sub 8}Se{sub 13} thermoelectric nano-composites

    SciTech Connect (OSTI)

    Hatzikraniotis, E. [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)] [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Ioannou, M. [Department of Mechanical and Manufacturing Engineering, University of Cyprus, 1678 Nicosia (Cyprus)] [Department of Mechanical and Manufacturing Engineering, University of Cyprus, 1678 Nicosia (Cyprus); Chrissafis, K. [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)] [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Chung, D.Y. [Materials Science Division, Argonne National Laboratory, Argonne, IL 60439 (United States)] [Materials Science Division, Argonne National Laboratory, Argonne, IL 60439 (United States); Paraskevopoulos, K.M. [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece)] [Department of Physics, Aristotle University of Thessaloniki, 54124 Thessaloniki (Greece); Kyratsi, Th., E-mail: kyratsi@ucy.ac.cy [Department of Mechanical and Manufacturing Engineering, University of Cyprus, 1678 Nicosia (Cyprus)

    2012-09-15T23:59:59.000Z

    K{sub 2}Bi{sub 8}Se{sub 13} has many attractive features for thermoelectric applications. Recently, K{sub 2}Bi{sub 8}Se{sub 13}-based nanocomposite materials, consisting of nano-crystalline, micro-crystalline and amorphous phases, have been fabricated based on powder technology techniques. The Seebeck coefficient has been enhanced while the thermal conductivity has been decreased presenting, thus, interesting behavior. The behavior of the materials under heat treatment conditions is now of interest, as the application of sintering process is necessary for the development of thermoelectric modules. In this work, the crystallization of the K{sub 2}Bi{sub 8}Se{sub 13}-based nano-composites is studied using Differential Scanning Calorimetry. The results show that crystallization follows a multiple-step process with different activation energies. The thermoelectric properties are also discussed in the range that crystallization occurs. - Graphical Abstract: {beta}-K{sub 2}Bi{sub 8}Se{sub 13}-based nanocomposites follow a multiple-step crystallization process. Highlights: Black-Right-Pointing-Pointer K{sub 2}Bi{sub 8}Se{sub 13}-based composites consisting of nanocrystalline and amorphous phases. Black-Right-Pointing-Pointer Sintering results multiple-step crystallization with variable activation energies. Black-Right-Pointing-Pointer Thermoelectric properties follow a step-like behavior during sintering. Black-Right-Pointing-Pointer Properties are attributed to the strain relaxation, nucleation and grain growth.

  19. Temperature, thermal-conductivity, and heat-flux data,Raft River...

    Open Energy Info (EERE)

    conductivity; United States; USGS Authors Urban, T.C.; Diment, W.H.; Nathenson, M.; Smith, E.P.; Ziagos, J.P.; Shaeffer and M.H. Published Open-File Report - U. S. Geological...

  20. Thermoelectrically cooled water trap

    DOE Patents [OSTI]

    Micheels, Ronald H. (Concord, MA)

    2006-02-21T23:59:59.000Z

    A water trap system based on a thermoelectric cooling device is employed to remove a major fraction of the water from air samples, prior to analysis of these samples for chemical composition, by a variety of analytical techniques where water vapor interferes with the measurement process. These analytical techniques include infrared spectroscopy, mass spectrometry, ion mobility spectrometry and gas chromatography. The thermoelectric system for trapping water present in air samples can substantially improve detection sensitivity in these analytical techniques when it is necessary to measure trace analytes with concentrations in the ppm (parts per million) or ppb (parts per billion) partial pressure range. The thermoelectric trap design is compact and amenable to use in a portable gas monitoring instrumentation.

  1. A new approach to low-conductivity, environmentally acceptable thermal insulation. Final report

    SciTech Connect (OSTI)

    Buckley, B.; Day, J.; Ferrero-Heredia, M.; Shanklin, E.; Varadarajan, G.; Woodruff, L.

    1996-02-01T23:59:59.000Z

    The object of this work was to develop a low-conductivity, economical, environmentally benign insulation. Specific objectives were to develop the following: (1) a very low conductivity use as ``super insulation`` in refrigerators, and (2) a general-purpose insulation for buildings and other applications. The technical goals of this work were to minimize gas phase, solid phase, and radiative conductivity. The novel approach pursued to achieve low gas phase conductivity was to blow foam with a removable gas or vapor, encapsulate the foam panel in a pouch made with a barrier film, and introduce a very low conductivity gas as the insulating gas phase. For super insulation and general-purpose insulation, the gases of choice were xenon and krypton, respectively. To control cost, the gases were present at low pressure, and the insulating panel was encapsulated with an impermeable polymeric film. Solid-phase conductivity was minimized by using low-density, open-cell, polyurethane foam. For super insulation, radiative heat transfer was impeded by placing aluminized Mylar films between relatively transparent 70-mil foam slabs. For general-purpose insulation, it was projected to impede radiative heat transfer by achieving the same very small cell size with open-cell CO{sub 2}-blown foam as is now achieved with closed-cell CO{sub 2}-blown foam.

  2. Nanoscale thermal transport. II. 2003–2012

    SciTech Connect (OSTI)

    Cahill, David G., E-mail: d-cahill@illinois.edu; Braun, Paul V. [Department of Materials Science and Engineering and the Frederick Seitz Materials Research Laboratory, University of Illinois, Urbana, Illinois 61801 (United States); Chen, Gang [Department of Mechanical Engineering, MIT, Cambridge, Massachusetts 02139 (United States); Clarke, David R. [School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Fan, Shanhui [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Goodson, Kenneth E. [Department of Mechanical Engineering, Stanford University, Stanford, California 94305 (United States); Keblinski, Pawel [Department of Materials Science and Engineering, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); King, William P. [Department of Mechanical Sciences and Engineering, University of Illinois, Urbana, Illinois 61801 (United States); Mahan, Gerald D. [Department of Physics, Penn State University, University Park, Pennsylvania 16802 (United States); Majumdar, Arun [Department of Mechanical Engineering, University of California, Berkeley, California 94720 (United States); Maris, Humphrey J. [Department of Physics, Brown University, Providence, Rhode Island 02912 (United States); Phillpot, Simon R. [Department of Materials Science and Engineering, University of Florida, Gainseville, Florida 32611 (United States); Pop, Eric [Department of Electrical and Computer Engineering, University of Illinois, Urbana, Illinois 61801 (United States); Shi, Li [Department of Mechanical Engineering, University of Texas, Autin, Texas 78712 (United States)

    2014-03-15T23:59:59.000Z

    A diverse spectrum of technology drivers such as improved thermal barriers, higher efficiency thermoelectric energy conversion, phase-change memory, heat-assisted magnetic recording, thermal management of nanoscale electronics, and nanoparticles for thermal medical therapies are motivating studies of the applied physics of thermal transport at the nanoscale. This review emphasizes developments in experiment, theory, and computation in the past ten years and summarizes the present status of the field. Interfaces become increasingly important on small length scales. Research during the past decade has extended studies of interfaces between simple metals and inorganic crystals to interfaces with molecular materials and liquids with systematic control of interface chemistry and physics. At separations on the order of ?1?nm, the science of radiative transport through nanoscale gaps overlaps with thermal conduction by the coupling of electronic and vibrational excitations across weakly bonded or rough interfaces between materials. Major advances in the physics of phonons include first principles calculation of the phonon lifetimes of simple crystals and application of the predicted scattering rates in parameter-free calculations of the thermal conductivity. Progress in the control of thermal transport at the nanoscale is critical to continued advances in the density of information that can be stored in phase change memory devices and new generations of magnetic storage that will use highly localized heat sources to reduce the coercivity of magnetic media. Ultralow thermal conductivity—thermal conductivity below the conventionally predicted minimum thermal conductivity—has been observed in nanolaminates and disordered crystals with strong anisotropy. Advances in metrology by time-domain thermoreflectance have made measurements of the thermal conductivity of a thin layer with micron-scale spatial resolution relatively routine. Scanning thermal microscopy and thermal analysis using proximal probes has achieved spatial resolution of 10?nm, temperature precision of 50 mK, sensitivity to heat flows of 10 pW, and the capability for thermal analysis of sub-femtogram samples.

  3. Thermal conductivity of Er{sup +3}:Y{sub 2}O{sub 3} films grown by atomic layer deposition

    SciTech Connect (OSTI)

    Raeisi Fard, Hafez; Hess, Andrew; Pashayi, Kamyar; Borca-Tasciuc, Theodorian, E-mail: borcat@rpi.edu [Mechanical, Aerospace and Nuclear Engineering Department, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States)] [Mechanical, Aerospace and Nuclear Engineering Department, Rensselaer Polytechnic Institute, Troy, New York 12180 (United States); Becker, Nicholas; Proslier, Thomas; Pellin, Michael [Material Sciences Division, Argonne National Laboratory 9700 S. Cass Avenue, Lemont, Illinois 60439 (United States)] [Material Sciences Division, Argonne National Laboratory 9700 S. Cass Avenue, Lemont, Illinois 60439 (United States)

    2013-11-04T23:59:59.000Z

    Cross-plane thermal conductivity of 800, 458, and 110?nm erbium-doped crystalline yttria (Er{sup +3}:Y{sub 2}O{sub 3}) films deposited via atomic layer deposition was measured using the 3? method at room temperature. Thermal conductivity results show 16-fold increase in thermal conductivity from 0.49?W m{sup ?1}K{sup ?1} to 8?W m{sup ?1}K{sup ?1} upon post deposition annealing, partially due to the suppression of the number of the -OH/H{sub 2}O bonds in the films after annealing. Thermal conductivity of the annealed film was ?70% lower than undoped bulk single crystal yttria. The cumulative interface thermal resistivity of substrate-Er{sup +3}:Y{sub 2}O{sub 3}-metal heater was determined to be ?2.5?×?10{sup ?8} m{sup 2} K/W.

  4. Reduction of thermal conductivity of anharmonic lattices Lei Wang1 and Baowen Li1,2,3,

    E-Print Network [OSTI]

    Li, Baowen

    /or heat "modulator." The physical mechanism for thermal diode and thermal transistor may be extended

  5. Using polymer electrolyte gates to set-and-freeze threshold voltage and local potential in nanowire-based devices and thermoelectrics

    E-Print Network [OSTI]

    Sofia Fahlvik Svensson; Adam M. Burke; Damon J. Carrad; Martin Leijnse; Heiner Linke; Adam P. Micolich

    2014-11-11T23:59:59.000Z

    We use the strongly temperature-dependent ionic mobility in polymer electrolytes to 'freeze in' specific ionic charge environments around a nanowire using a local wrap-gate geometry. This enables us to set both the threshold voltage for a conventional doped substrate gate and the local disorder potential at temperatures below 200 Kelvin, which we characterize in detail by combining conductance and thermovoltage measurements with modeling. Our results demonstrate that local polymer electrolyte gates are compatible with nanowire thermoelectrics, where they offer the advantage of a very low thermal conductivity, and hold great potential towards setting the optimal operating point for solid-state cooling applications.

  6. Simulated evolution of fractures and fracture networks subject to thermal cooling: A coupled discrete element and heat conduction model

    SciTech Connect (OSTI)

    Huang, Hai; Plummer, Mitchell; Podgorney, Robert

    2013-02-01T23:59:59.000Z

    Advancement of EGS requires improved prediction of fracture development and growth during reservoir stimulation and long-term operation. This, in turn, requires better understanding of the dynamics of the strongly coupled thermo-hydro-mechanical (THM) processes within fractured rocks. We have developed a physically based rock deformation and fracture propagation simulator by using a quasi-static discrete element model (DEM) to model mechanical rock deformation and fracture propagation induced by thermal stress and fluid pressure changes. We also developed a network model to simulate fluid flow and heat transport in both fractures and porous rock. In this paper, we describe results of simulations in which the DEM model and network flow & heat transport model are coupled together to provide realistic simulation of the changes of apertures and permeability of fractures and fracture networks induced by thermal cooling and fluid pressure changes within fractures. Various processes, such as Stokes flow in low velocity pores, convection-dominated heat transport in fractures, heat exchange between fluid-filled fractures and solid rock, heat conduction through low-permeability matrices and associated mechanical deformations are all incorporated into the coupled model. The effects of confining stresses, developing thermal stress and injection pressure on the permeability evolution of fracture and fracture networks are systematically investigated. Results are summarized in terms of implications for the development and evolution of fracture distribution during hydrofracturing and thermal stimulation for EGS.

  7. Thermal conductance of the junction between single-walled carbon nanotubes

    E-Print Network [OSTI]

    McGaughey, Alan

    conductances of the carbon nanotube (CNT) junctions that would be found in a CNT aerogel are predicted using of carbon nanotubes (CNTs) (e.g., aligned films, mats, and aerogels) are candidates for use in electronic issue in all of these applications. Our focus here is related to single-walled CNT aerogels, which

  8. Effects of axial plate heat conduction on the thermal performance of a laminar counterflow flat plate heat exchanger

    E-Print Network [OSTI]

    Demko, Jonathan Alexander

    1980-01-01T23:59:59.000Z

    THEN THE CENTERLINE TEHPERATUBES EY USING THZ ENERGY EQUATION AIONG THE CENTERLINE FINALLY E VAL HAT I THE FLO W FIELD EPS= 1, OD-04 DO 999 K=1, 850 REST=0 ~ 0 DO DO 70 J=1rM TH {N, J)= (4 DU?TH (8-1, J) -TH(8-2 ~ J) ) /3 DO DO 60 I= 2, 8L TH (I, M) = (DY2... thermal conductivity ratios of the plate to the fluid, dimensionless plate thicknesses, Reynolds and Prandtl numbers. ACKNOWLEDGEMENTS I would like to express my thanks to all those who gave me support while I was working toward this goal. Dr. Louis...

  9. The thermally stimulated conductivity in amorphous thin film As?Se?

    E-Print Network [OSTI]

    Bryant, John Duffie

    1972-01-01T23:59:59.000Z

    V with a 14 -3 density of 9. 73 x 10 cm . The thermal velocity of the carriers 6 -18 was 6. 34 x 10 cm/sec, and the capture cross section was 2. 7 x 10 2 cm . These results indicate that the Nett-Davis model is more ap- plicable to amorphous As Se... II-3 Sample Holder Design (not to scale) 15 16 17 11-4 Output Curve for Chromel-Constantan Thermo- couple (Voltage vs. Temperature) (ref. 29) 19 II-5 System Cooling Curve (Temperature vs. Time) 20 II-6 System Heating Curve for a Constant Heater...

  10. The thermally stimulated conductivity in amorphous thin film As?Se? 

    E-Print Network [OSTI]

    Bryant, John Duffie

    1972-01-01T23:59:59.000Z

    V with a 14 -3 density of 9. 73 x 10 cm . The thermal velocity of the carriers 6 -18 was 6. 34 x 10 cm/sec, and the capture cross section was 2. 7 x 10 2 cm . These results indicate that the Nett-Davis model is more ap- plicable to amorphous As Se... II-3 Sample Holder Design (not to scale) 15 16 17 11-4 Output Curve for Chromel-Constantan Thermo- couple (Voltage vs. Temperature) (ref. 29) 19 II-5 System Cooling Curve (Temperature vs. Time) 20 II-6 System Heating Curve for a Constant Heater...

  11. Nanostructured High Temperature Bulk Thermoelectric Energy Conversion...

    Broader source: Energy.gov (indexed) [DOE]

    Thermoelectric Energy Conversion for Efficient Waste Heat Recovery PI - Chris Caylor, GMZ Director of Thermoelectric Systems GMZ Team: Bed Poudel, Giri Joshi, Jonathan D'Angelo,...

  12. Correlation Between Structure and Thermoelectric Properties of...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Correlation Between Structure and Thermoelectric Properties of Bulk High Performance Materials for Energy Conversion Correlation Between Structure and Thermoelectric Properties of...

  13. Recent Device Developments with Advanced Bulk Thermoelectric...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Device Developments with Advanced Bulk Thermoelectric Materials at RTI Recent Device Developments with Advanced Bulk Thermoelectric Materials at RTI Reviews work in engineered...

  14. Advanced Thermoelectric Materials and Generator Technology for...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Thermoelectric Materials and Generator Technology for Automotive Waste Heat at GM Advanced Thermoelectric Materials and Generator Technology for Automotive Waste Heat at GM...

  15. Skutterudite Thermoelectric Generator For Automotive Waste Heat...

    Broader source: Energy.gov (indexed) [DOE]

    Skutterudite Thermoelectric Generator For Automotive Waste Heat Recovery Gregory P. Meisner General Motors Global Research & Development March 21, 2012 3rd Thermoelectric...

  16. Development of Thermoelectric Technology for Automotive Waste...

    Energy Savers [EERE]

    Development of Thermoelectric Technology for Automotive Waste Heat Recovery Development of Thermoelectric Technology for Automotive Waste Heat Recovery Presentation from the U.S....

  17. Vehicle Fuel Economy Improvement through Thermoelectric Waste...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Fuel Economy Improvement through Thermoelectric Waste Heat Recovery Vehicle Fuel Economy Improvement through Thermoelectric Waste Heat Recovery 2005 Diesel Engine Emissions...

  18. Integrated Design and Manufacturing of Thermoelectric Generator...

    Office of Environmental Management (EM)

    High-Performance Thermoelectric Devices Based on Abundant Silicide Materials for Vehicle Waste Heat Recovery High-Performance Thermoelectric Devices Based on Abundant Silicide...

  19. Nanostructured High Temperature Bulk Thermoelectric Energy Conversion...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    High Temperature Bulk Thermoelectric Energy Conversion for Efficient Waste Heat Recovery Nanostructured High Temperature Bulk Thermoelectric Energy Conversion for Efficient Waste...

  20. Investigations of Interfacial Structure in Thermoelectric Tellurides...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    More Documents & Publications Thermoelectric Materials by Design, Computational Theory and Structure Strategies for High Thermoelectric zT in Bulk Materials Strategies for...

  1. Method for the thermal characterization, visualization, and integrity evaluation of conducting material samples or complex structures

    DOE Patents [OSTI]

    Ortiz, Marcos G. (Idaho Falls, ID)

    1992-01-01T23:59:59.000Z

    A method for modeling a conducting material sample or structure (herein called a system) as at least two regions which comprise an electrical network of resistances, for measuring electric resistance between at least two selected pairs of external leads attached to the surface of the system, wherein at least one external lead is attached to the surface of each of the regions, and, using basic circuit theory, for translating measured resistances into temperatures or thermophysical properties in corresponding regions of the system.

  2. Thermoelectric generators incorporating phase-change materials for waste heat recovery from engine exhaust

    DOE Patents [OSTI]

    Meisner, Gregory P; Yang, Jihui

    2014-02-11T23:59:59.000Z

    Thermoelectric devices, intended for placement in the exhaust of a hydrocarbon fuelled combustion device and particularly suited for use in the exhaust gas stream of an internal combustion engine propelling a vehicle, are described. Exhaust gas passing through the device is in thermal communication with one side of a thermoelectric module while the other side of the thermoelectric module is in thermal communication with a lower temperature environment. The heat extracted from the exhaust gasses is converted to electrical energy by the thermoelectric module. The performance of the generator is enhanced by thermally coupling the hot and cold junctions of the thermoelectric modules to phase-change materials which transform at a temperature compatible with the preferred operating temperatures of the thermoelectric modules. In a second embodiment, a plurality of thermoelectric modules, each with a preferred operating temperature and each with a uniquely-matched phase-change material may be used to compensate for the progressive lowering of the exhaust gas temperature as it traverses the length of the exhaust pipe.

  3. Fully-coupled engineering and mesoscale simulations of thermal conductivity in UO2 fuel using an implicit multiscale approach

    SciTech Connect (OSTI)

    Michael Tonks; Derek Gaston; Cody Permann; Paul Millett; Glen Hansen; Chris Newman

    2009-08-01T23:59:59.000Z

    Reactor fuel performance is sensitive to microstructure changes during irradiation (such as fission gas and pore formation). This study proposes an approach to capture microstructural changes in the fuel by a two-way coupling of a mesoscale phase field irradiation model to an engineering scale, finite element calculation. This work solves the multiphysics equation system at the engineering-scale in a parallel, fully-coupled, fully-implicit manner using a preconditioned Jacobian-free Newton Krylov method (JFNK). A sampling of the temperature at the Gauss points of the coarse scale is passed to a parallel sequence of mesoscale calculations within the JFNK function evaluation phase of the calculation. The mesoscale thermal conductivity is calculated in parallel, and the result is passed back to the engineering-scale calculation. As this algorithm is fully contained within the JFNK function evaluation, the mesoscale calculation is nonlinearly consistent with the engineering-scale calculation. Further, the action of the Jacobian is also consistent, so the composite algorithm provides the strong nonlinear convergence properties of Newton's method. The coupled model using INL's \\bison\\ code demonstrates quadratic nonlinear convergence and good parallel scalability. Initial results predict the formation of large pores in the hotter center of the pellet, but few pores on the outer circumference. Thus, the thermal conductivity is is reduced in the center of the pellet, leading to a higher internal temperature than that in an unirradiated pellet.

  4. Investigation of the thermal conductivity of unconsolidated sand packs containing oil, water, and gas

    E-Print Network [OSTI]

    Gore, David Eugene

    1958-01-01T23:59:59.000Z

    of the requirements for the degree of EASTER OF SCIENCE August, lBSS Najor Subject: Petroleum Engineering INVESTIGATION OF THE THERNAI CONDUCTIVITY OF UNCONSOI IDATED SAND PACKS CONTAINING OII, WATER, AND GAS A Thesis By David E, Gore APProved as to style... expressed in degrees Fahrenheit, and, at 0 oF, , the abscissa would become ini'inite. This restriction does not limit the application of the data to petroleum reservoirs as the tem- perature normally encountered is in excess of 100 oF. The reservoir...

  5. Electrical network method for the thermal or structural characterization of a conducting material sample or structure

    DOE Patents [OSTI]

    Ortiz, M.G.

    1993-06-08T23:59:59.000Z

    A method for modeling a conducting material sample or structure system, as an electrical network of resistances in which each resistance of the network is representative of a specific physical region of the system. The method encompasses measuring a resistance between two external leads and using this measurement in a series of equations describing the network to solve for the network resistances for a specified region and temperature. A calibration system is then developed using the calculated resistances at specified temperatures. This allows for the translation of the calculated resistances to a region temperature. The method can also be used to detect and quantify structural defects in the system.

  6. Method for the thermal characterization, visualization, and integrity evaluation of conducting material samples or complex structures

    DOE Patents [OSTI]

    Ortiz, M.G.

    1992-11-24T23:59:59.000Z

    Disclosed is a method for modeling a conducting material sample or structure (herein called a system) as at least two regions which comprise an electrical network of resistances, for measuring electric resistance between at least two selected pairs of external leads attached to the surface of the system, wherein at least one external lead is attached to the surface of each of the regions, and, using basic circuit theory, for translating measured resistances into temperatures or thermophysical properties in corresponding regions of the system. 16 figs.

  7. Electrical conductivity and charge diffusion in thermal QCD from the lattice

    E-Print Network [OSTI]

    Gert Aarts; Chris Allton; Alessandro Amato; Pietro Giudice; Simon Hands; Jon-Ivar Skullerud

    2015-02-12T23:59:59.000Z

    We present a lattice QCD calculation of the charge diffusion coefficient, the electrical conductivity and various susceptibilities of conserved charges, for a range of temperatures below and above the deconfinement crossover. The calculations include the contributions from up, down and strange quarks. We find that the diffusion coefficient is of the order of 1/(2\\pi T) and has a dip around the crossover temperature. Our results are obtained with lattice simulations containing 2+1 dynamical flavours on anisotropic lattices. The Maximum Entropy Method is used to construct spectral functions from correlators of the conserved vector current.

  8. Manipulation of Thermal Phonons 

    E-Print Network [OSTI]

    Hsu, Chung-Hao

    2013-03-28T23:59:59.000Z

    Developing materials that can conduct electricity easily, but block the motion of phonons is necessary in the applications of thermoelectric devices, which can generate electricity from temperature differences. In converse, a key requirement...

  9. Thermal Conductivity Measurement of Xe-Implanted Uranium Dioxide Thick Films using Multilayer Laser Flash Analysis

    SciTech Connect (OSTI)

    Nelson, Andrew T. [Los Alamos National Laboratory

    2012-08-30T23:59:59.000Z

    The Fuel Cycle Research and Development program's Advanced Fuels campaign is currently pursuing use of ion beam assisted deposition to produce uranium dioxide thick films containing xenon in various morphologies. To date, this technique has provided materials of interest for validation of predictive fuel performance codes and to provide insight into the behavior of xenon and other fission gasses under extreme conditions. In addition to the structural data provided by such thick films, it may be possible to couple these materials with multilayer laser flash analysis in order to measure the impact of xenon on thermal transport in uranium dioxide. A number of substrate materials (single crystal silicon carbide, molybdenum, and quartz) containing uranium dioxide films ranging from one to eight microns in thickness were evaluated using multilayer laser flash analysis in order to provide recommendations on the most promising substrates and geometries for further investigation. In general, the uranium dioxide films grown to date using ion beam assisted deposition were all found too thin for accurate measurement. Of the substrates tested, molybdenum performed the best and looks to be the best candidate for further development. Results obtained within this study suggest that the technique does possess the necessary resolution for measurement of uranium dioxide thick films, provided the films are grown in excess of fifty microns. This requirement is congruent with the material needs when viewed from a fundamental standpoint, as this length scale of material is required to adequately sample grain boundaries and possible second phases present in ceramic nuclear fuel.

  10. Total thermoelectric-power withdrawals Freshwater thermoelectric-power withdrawals Saline-water thermoelectric-power withdrawals

    E-Print Network [OSTI]

    Total thermoelectric-power withdrawals Freshwater thermoelectric-power withdrawals Saline-water thermoelectric-power withdrawals Louisiana New Hampshire Florida Idaho Washington Oregon Nevada California New,000 9,000 to 13,000 Thermoelectric-power withdrawals by water quality and State, 2005. Estimated Use

  11. High Temperature Experimental Characterization of Microscale Thermoelectric Effects

    E-Print Network [OSTI]

    Favaloro, Tela

    2014-01-01T23:59:59.000Z

    Mission Radioisotope Thermoelectric Generator (MMRTG) FactFigure 1.1: Radioisotope thermoelectric generator used byhand side radioisotope thermoelectric generator reflectivity

  12. High Heat Flux Thermoelectric Module Using Standard Bulk Material...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Heat Flux Thermoelectric Module Using Standard Bulk Material High Heat Flux Thermoelectric Module Using Standard Bulk Material Presents high heat flux thermoelectric module design...

  13. Thermoelectric effect in very thin film Pt/Au thermocouples

    E-Print Network [OSTI]

    Salvadori, M.C.; Vaz, A.R.; Teixeira, F.S.; Cattani, M.; Brown, I.G.

    2006-01-01T23:59:59.000Z

    TABLE I. Measured thermoelectric power S for samples ofThermoelectric effect in very thin film Pt/Au thermocouplesthickness dependence of the thermoelectric power of Pt films

  14. Thermoelectric transport in the coupled valence-band model

    E-Print Network [OSTI]

    Ramu, Ashok; Cassels, Laura; Hackman, Nathan; Lu, Hong; Zide, Joshua; Bowers, John E.

    2011-01-01T23:59:59.000Z

    109, 033704 ?2011? Thermoelectric transport in the coupledapplied to the problem of thermoelectric transport in p-typeef?ciency p-type thermoelectric material, are calculated and

  15. Effect of Nanoparticles on Electron and Thermoelectric Transport

    E-Print Network [OSTI]

    2009-01-01T23:59:59.000Z

    on Electron and Thermoelectric Transport MONA ZEBARJADI, 1,5can enhance the thermoelectric performance by reducing thepredictions for the thermoelectric properties such as the

  16. NSF/DOE Thermoelectric Partnership: Inorganic-Organic Hybrid...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Inorganic-Organic Hybrid Thermoelectrics NSFDOE Thermoelectric Partnership: Inorganic-Organic Hybrid Thermoelectrics 2011 DOE Hydrogen and Fuel Cells Program, and Vehicle...

  17. NSF/DOE Thermoelectrics Partnership: Purdue ? GM Partnership...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Purdue GM Partnership on Thermoelectrics for Automotive Waste Heat Recovery NSFDOE Thermoelectrics Partnership: Purdue GM Partnership on Thermoelectrics for Automotive Waste...

  18. Synthesis of new thermoelectrics using modulated elemental reactants

    SciTech Connect (OSTI)

    Hornbostel, M.D.; Sellinschegg, H.; Johnson, D.C.

    1997-07-01T23:59:59.000Z

    A series of new, metastable ternary crystalline compounds with the skutterudite crystal structure have been synthesized using modulated elemental reactants. The initial reactants are made up of multiple repeats of a {approximately}25 {angstrom} thick unit containing elemental layers of the desired ternary metal, iron and antimony. Low temperature annealing (150 C) results in interdiffusion of the elemental layers to form amorphous reaction intermediates. Annealing these intermediates at temperatures between 200 C and 250 C results in exothermic crystallization of the desired skutterudite crystal structure. Most of the new compounds prepared are only kinetically stable, decomposing exothermically to form thermodynamically more stable mixtures of binary compounds and elements. Low angle x-ray diffraction studies show that the resulting films are exceedingly smooth. These films have an ideal geometry for measuring properties of importance for thermoelectric devices--the Seebeck coefficient and the electrical conductivity. Thermal conductivity can be measured using a modification of the 3{omega} technique of Cahill. Samples can be produced rapidly, allowing for systematic screening and subsequent optimization as a function of composition and doping levels.

  19. Effect of substrate on thermal conductivity of single-walled carbon nanotubes This article has been downloaded from IOPscience. Please scroll down to see the full text article.

    E-Print Network [OSTI]

    Effect of substrate on thermal conductivity of single-walled carbon nanotubes This article has been conductivity of single-walled carbon nanotubes A. V. Savin1,2(a) , Y. S. Kivshar2 and B. Hu3,4 1 Semenov, China 4 Department of Physics, University of Houston - Houston, TX 77204-5005, USA received 10 June 2009

  20. ANISOTROPIC THERMAL CONDUCTIVITY IN A DIRTY TYPE II SUPERCONDUCTOR J.P.M. Van der Veeken, P.H. Kes and D. de Klerk

    E-Print Network [OSTI]

    Boyer, Edmond

    ANISOTROPIC THERMAL CONDUCTIVITY IN A DIRTY TYPE II SUPERCONDUCTOR J.P.M. Van der Veeken, P.H. Kes, The results are compared with calculations by Watts - Tobin and Imai. For dirty type II superconductors) of the total conductivities. ii) The theoretical calculations are valid only for BCS - superconductors

  1. Proposal for a phase-coherent thermoelectric transistor

    SciTech Connect (OSTI)

    Giazotto, F., E-mail: giazotto@sns.it [NEST, Instituto Nanoscienze-CNR and Scuola Normale Superiore, I-56127 Pisa (Italy); Robinson, J. W. A., E-mail: jjr33@cam.ac.uk [Department of Materials Science and Metallurgy, University of Cambridge, 27 Charles Babbage Road, Cambridge CB3 0FS (United Kingdom); Moodera, J. S. [Department of Physics and Francis Bitter Magnet Lab, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Bergeret, F. S., E-mail: sebastian-bergeret@ehu.es [Centro de Física de Materiales (CFM-MPC), Centro Mixto CSIC-UPV/EHU, Manuel de Lardizabal 4, E-20018 San Sebastián (Spain); Donostia International Physics Center (DIPC), Manuel de Lardizabal 5, E-20018 San Sebastián (Spain)

    2014-08-11T23:59:59.000Z

    Identifying materials and devices which offer efficient thermoelectric effects at low temperature is a major obstacle for the development of thermal management strategies for low-temperature electronic systems. Superconductors cannot offer a solution since their near perfect electron-hole symmetry leads to a negligible thermoelectric response; however, here we demonstrate theoretically a superconducting thermoelectric transistor which offers unparalleled figures of merit of up to ?45 and Seebeck coefficients as large as a few mV/K at sub-Kelvin temperatures. The device is also phase-tunable meaning its thermoelectric response for power generation can be precisely controlled with a small magnetic field. Our concept is based on a superconductor-normal metal-superconductor interferometer in which the normal metal weak-link is tunnel coupled to a ferromagnetic insulator and a Zeeman split superconductor. Upon application of an external magnetic flux, the interferometer enables phase-coherent manipulation of thermoelectric properties whilst offering efficiencies which approach the Carnot limit.

  2. Thermal conductivity of large-grain niobium and its effect on trapped vortices in the temperature range 1.8?5 K

    SciTech Connect (OSTI)

    Mondal, Jayanta [Bhabha Atomic Research Centre; Ciovati, Gianluigi [JLAB; Mittal, Kailash C. [Bhabha Atomic Research Centre; Myneni, Ganapati Rao [JLAB

    2012-04-01T23:59:59.000Z

    Experimental investigation of the thermal conductivity of large grain and its dependence on the trapped vortices in parallel magnetic field with respect to the temperature gradient {gradient}T was carried out on four large-grain niobium samples from four different ingots. The zero-field thermal conductivity measurements are in good agreement with the measurements based on the theory of Bardeen-Rickayzen-Tewordt (BRT). The change in thermal conductivity with trapped vortices is analysed with the field dependence of the conductivity results of Vinen et al for low inductions and low-temperature situation. Finally, the dependence of thermal conductivity on the applied magnetic field in the vicinity of the upper critical field H{sub c2} is fitted with the theory of pure type-II superconductor of Houghton and Maki. Initial remnant magnetization in the sample shows a departure from the Houghton?Maki curve whereas the sample with zero trapped flux qualitatively agrees with the theory. A qualitative discussion is presented explaining the reason for such deviation from the theory. It has also been observed that if the sample with the trapped vortices is cycled through T{sub c}, the subsequent measurement of the thermal conductivity coincides with the zero trapped flux results.

  3. Thermoelectric system for an engine

    DOE Patents [OSTI]

    Mcgilvray, Andrew N.; Vachon, John T.; Moser, William E.

    2010-06-22T23:59:59.000Z

    An internal combustion engine that includes a block, a cylinder head having an intake valve port and exhaust valve port formed therein, a piston, and a combustion chamber defined by the block, the piston, and the head. At least one thermoelectric device is positioned within either or both the intake valve port and the exhaust valve port. Each of the valves is configured to move within a respective intake and exhaust valve port thereby causing said valves to engage the thermoelectric devices resulting in heat transfer from the valves to the thermoelectric devices. The intake valve port and exhaust valve port are configured to fluidly direct intake air and exhaust gas, respectively, into the combustion chamber and the thermoelectric device is positioned within the intake valve port, and exhaust valve port, such that the thermoelectric device is in contact with the intake air and exhaust gas.

  4. Research on Short-term Load Forecasting of the Thermoelectric Boiler Based on a Dynamic RBF Neural Network 

    E-Print Network [OSTI]

    Dai, W.; Zou, P.; Yan, C.

    2006-01-01T23:59:59.000Z

    As thermal inertia is the key factor for the lag of thermoelectric utility regulation, it becomes very important to forecast its short-term load according to running parameters. In this paper, dynamic radial basis function (RBF) neural network...

  5. The effect of Coulomb interactions on thermoelectric properties of quantum dots

    SciTech Connect (OSTI)

    Zimbovskaya, Natalya A. [Department of Physics and Electronics, University of Puerto Rico-Humacao, CUH Station, Humacao, Puerto Rico 00791, USA and Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Ruco 00931 (United States)] [Department of Physics and Electronics, University of Puerto Rico-Humacao, CUH Station, Humacao, Puerto Rico 00791, USA and Institute for Functional Nanomaterials, University of Puerto Rico, San Juan, Puerto Ruco 00931 (United States)

    2014-03-14T23:59:59.000Z

    Thermoelectric effects in a quantum dot coupled to the source and drain charge reservoirs are explored using a nonequilibrium Green's functions formalism beyond the Hartree-Fock approximation. Thermal transport is analyzed within a linear response regime. A transition from Coulomb blockade regime to Kondo regime in thermoelectric transport through a single-level quantum dot is traced using unified approximations for the relevant Green's functions.

  6. Experimental investigations and theoretical determination of thermal conductivity and viscosity of Al{sub 2}O{sub 3}/water nanofluid

    SciTech Connect (OSTI)

    Chandrasekar, M.; Suresh, S. [Department of Mechanical Engineering, National Institute of Technology, Tiruchirappalli 620 015 (India); Chandra Bose, A. [Nanomaterials Laboratory, National Institute of Technology, Tiruchirappalli 620 015 (India)

    2010-02-15T23:59:59.000Z

    Experimental investigations and theoretical determination of effective thermal conductivity and viscosity of Al{sub 2}O{sub 3}/H{sub 2}O nanofluid are reported in this paper. The nanofluid was prepared by synthesizing Al{sub 2}O{sub 3} nanoparticles using microwave assisted chemical precipitation method, and then dispersing them in distilled water using a sonicator. Al{sub 2}O{sub 3}/water nanofluid with a nominal diameter of 43 nm at different volume concentrations (0.33-5%) at room temperature were used for the investigation. The thermal conductivity and viscosity of nanofluids are measured and it is found that the viscosity increase is substantially higher than the increase in thermal conductivity. Both the thermal conductivity and viscosity of nanofluids increase with the nanoparticle volume concentration. Theoretical models are developed to predict thermal conductivity and viscosity of nanofluids without resorting to the well established Maxwell and Einstein models, respectively. The proposed models show reasonably good agreement with our experimental results. (author)

  7. Influence of longitudinal isotope substitution on the thermal conductivity of carbon nanotubes: Results of nonequilibrium molecular dynamics and local density functional calculations

    SciTech Connect (OSTI)

    Leroy, Frédéric, E-mail: f.leroy@theo.chemie.tu-darmstadt.de; Böhm, Michael C., E-mail: boehm@theo.chemie.tu-darmstadt.de [Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, D-64287 Darmstadt (Germany); Schulte, Joachim [Bruker Biospin GmbH, Silberstreifen, D-76287 Rheinstetten (Germany)] [Bruker Biospin GmbH, Silberstreifen, D-76287 Rheinstetten (Germany); Balasubramanian, Ganesh [Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011 (United States)] [Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011 (United States)

    2014-04-14T23:59:59.000Z

    We report reverse nonequilibrium molecular dynamics calculations of the thermal conductivity of isotope substituted (10,10) carbon nanotubes (CNTs) at 300 K. {sup 12}C and {sup 14}C isotopes both at 50% content were arranged either randomly, in bands running parallel to the main axis of the CNTs or in bands perpendicular to this axis. It is found that the systems with randomly distributed isotopes yield significantly reduced thermal conductivity. In contrast, the systems where the isotopes are organized in patterns parallel to the CNTs axis feature no reduction in thermal conductivity when compared with the pure {sup 14}C system. Moreover, a reduction of approximately 30% is observed in the system with the bands of isotopes running perpendicular to the CNT axis. The computation of phonon dispersion curves in the local density approximation and classical densities of vibrational states reveal that the phonon structure of carbon nanotubes is conserved in the isotope substituted systems with the ordered patterns, yielding high thermal conductivities in spite of the mass heterogeneity. In order to complement our conclusions on the {sup 12}C-{sup 14}C mixtures, we computed the thermal conductivity of systems where the {sup 14}C isotope was turned into pseudo-atoms of 20 and 40 atomic mass units.

  8. Manufacture of thermoelectric generator structures by fiber drawing

    DOE Patents [OSTI]

    McIntyre, Timothy J; Simpson, John T; West, David L

    2014-11-18T23:59:59.000Z

    Methods of manufacturing a thermoelectric generator via fiber drawing and corresponding or associated thermoelectric generator devices are provided.

  9. Develop Thermoelectric Technology for Automotive Waste Heat Recovery...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    More Documents & Publications Develop Thermoelectric Technology for Automotive Waste Heat Recovery Engineering and Materials for Automotive Thermoelectric Applications...

  10. NSF/DOE Thermoelectics Partnership: Thermoelectrics for Automotive...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Thermoelectics Partnership: Thermoelectrics for Automotive Waste Heat Recovery NSFDOE Thermoelectics Partnership: Thermoelectrics for Automotive Waste Heat Recovery 2011 DOE...

  11. Develop Thermoelectric Technology for Automotive Waste Heat Recovery...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    More Documents & Publications Develop Thermoelectric Technology for Automotive Waste Heat Recovery Cost-Competitive Advanced Thermoelectric Generators for Direct...

  12. Develop Thermoelectric Technology for Automotive Waste Heat Recovery...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    More Documents & Publications Skutterudite Thermoelectric Generator For Automotive Waste Heat Recovery Thermoelectric Conversion of Exhaust Gas Waste Heat into Usable...

  13. Develop Thermoelectric Technology for Automotive Waste Heat Recovery...

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    More Documents & Publications Development of Thermoelectric Technology for Automotive Waste Heat Recovery Development of Thermoelectric Technology for Automotive Waste Heat...

  14. Certification testing of the Los Alamos National Laboratory Heat Source/Radioisotopic Thermoelectric Generator shipping container

    SciTech Connect (OSTI)

    Bronowski, D.R.; Madsen, M.M.

    1991-09-01T23:59:59.000Z

    The Heat Source/Radioisotopic Thermoelectric Generator shipping counter is a Type B packaging currently under development by Los Alamos National Laboratory. Type B packaging for transporting radioactive material is required to maintain containment and shielding after being exposed to normal and hypothetical accident environments defined in Title 10 of the Code of Federal Regulations Part 71. A combination of testing and analysis is used to verify the adequacy of this packaging design. This report documents the testing portion of the design verification. Six tests were conducted on a prototype package: a water spray test, a 4-foot normal conditions drop test, a 30-foot drop test, a 40-inch puncture test, a 30-minute thermal test, and an 8-hour immersion test.

  15. Spin-on-doping for output power improvement of silicon nanowire array based thermoelectric power generators

    SciTech Connect (OSTI)

    Xu, B., E-mail: bin.xu09@imperial.ac.uk; Fobelets, K. [Department of Electrical and Electronic Engineering, Imperial College London, Exhibition Road, SW7 2BT London (United Kingdom)

    2014-06-07T23:59:59.000Z

    The output power of a silicon nanowire array (NWA)-bulk thermoelectric power generator (TEG) with Cu contacts is improved by spin-on-doping (SOD). The Si NWAs used in this work are fabricated via metal assisted chemical etching (MACE) of 0.01–0.02 ? cm resistivity n- and p-type bulk, converting ?4% of the bulk thickness into NWs. The MACE process is adapted to ensure crystalline NWs. Current-voltage and Seebeck voltage-temperature measurements show that while SOD mainly influences the contact resistance in bulk, it influences both contact resistance and power factor in NWA-bulk based TEGs. According to our experiments, using Si NWAs in combination with SOD increases the output power by an order of 3 under the same heating power due to an increased power factor, decreased thermal conductivity of the NWA and reduced Si-Cu contact resistance.

  16. Cylindrical thermal contact conductance

    E-Print Network [OSTI]

    Ayers, George Harold

    2004-09-30T23:59:59.000Z

    of superconducting wires, tension-wound finned tubes, and large diameter pipes. Thick cylindrical shells (including solid composite cylinders) may occur in such applications as nuclear fuel rods and composite pipes. Cylindrical joints behave differently than flat...

  17. Thermoelectric generator for motor vehicle

    DOE Patents [OSTI]

    Bass, John C. (6121 La Pintra Dr., La Jolla, CA 92037)

    1997-04-29T23:59:59.000Z

    A thermoelectric generator for producing electric power for a motor vehicle from the heat of the exhaust gasses produced by the engine of the motor vehicle. The exhaust gasses pass through a finned heat transfer support structure which has seat positions on its outside surface for the positioning of thermoelectric modules. A good contact cylinder provides a framework from which a spring force can be applied to the thermoelectric modules to hold them in good contact on their seats on the surface of the heat transfer support structure.

  18. Effect of in-pile degradation of the meat thermal conductivity on the maximum temperature of the plate-type U-Mo dispersion fuels

    SciTech Connect (OSTI)

    Pavel G. Medvedev

    2009-11-01T23:59:59.000Z

    Effect of in-pile degradation of thermal conductivity on the maximum temperature of the plate-type research reactor fuels has been assessed using the steady-state heat conduction equation and assuming convection cooling. It was found that due to very low meat thickness, characteristic for this type of fuel, the effect of thermal conductivity degradation on the maximum fuel temperature is minor. For example, the fuel plate featuring 0.635 mm thick meat operating at heat flux of 600 W/cm2 would experience only a 20oC temperature rise if the meat thermal conductivity degrades from 0.8 W/cm-s to 0.3 W/cm-s. While degradation of meat thermal conductivity in dispersion-type U-Mo fuel can be very substantial due to formation of interaction layer between the particles and the matrix, and development of fission gas filled porosity, this simple analysis demonstrates that this phenomenon is unlikely to significantly affect the temperature-based safety margin of the fuel during normal operation.

  19. International Round-Robin Testing of Bulk Thermoelectrics

    SciTech Connect (OSTI)

    Wang, Hsin [ORNL; Porter, Wallace D [ORNL; Bottner, Harold [Fraunhofer-Institute, Freiburg, Germany; Konig, Jan [Fraunhofer-Institute, Freiburg, Germany; Chen, Lidong [Chinese Academy of Sciences; Bai, Shengqiang [Chinese Academy of Sciences; Tritt, Terry M. [Clemson University; Mayolett, Alex [Corning, Inc; Smith, Charlene [Corning, Inc; Harris, Fred [ZT-Plus; Sharp, Jeff [Marlow Industries, Inc; Lo, Jason [CANMET - Materials Technology Laboratory, Natural Resources of Canada; Keinke, Holger [University of Waterloo, Canada; Kiss, Laszlo I. [University of Quebec at Chicoutimi

    2011-11-01T23:59:59.000Z

    Two international round-robin studies were conducted on transport properties measurements of bulk thermoelectric materials. The study discovered current measurement problems. In order to get ZT of a material four separate transport measurements must be taken. The round-robin study showed that among the four properties Seebeck coefficient is the one can be measured consistently. Electrical resistivity has +4-9% scatter. Thermal diffusivity has similar +5-10% scatter. The reliability of the above three properties can be improved by standardizing test procedures and enforcing system calibrations. The worst problem was found in specific heat measurements using DSC. The probability of making measurement error is great due to the fact three separate runs must be taken to determine Cp and the baseline shift is always an issue for commercial DSC. It is suggest the Dulong Petit limit be always used as a guide line for Cp. Procedures have been developed to eliminate operator and system errors. The IEA-AMT annex is developing standard procedures for transport properties testing.

  20. The cross-plane thermoelectric properties of p-Ge/Si{sub 0.5}Ge{sub 0.5} superlattices

    SciTech Connect (OSTI)

    Ferre Llin, L.; Samarelli, A.; Weaver, J. M. R.; Dobson, P. S.; Paul, D. J. [School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LT (United Kingdom)] [School of Engineering, University of Glasgow, Rankine Building, Oakfield Avenue, Glasgow G12 8LT (United Kingdom); Cecchi, S.; Chrastina, D.; Isella, G. [L-NESS, Politecnico di Milano, Via Anzani 42, 22100 Como (Italy)] [L-NESS, Politecnico di Milano, Via Anzani 42, 22100 Como (Italy); Etzelstorfer, T.; Stangl, J. [Institute of Semiconductor and Solid State Physics, Johannes Kepler Universität, Linz (Austria)] [Institute of Semiconductor and Solid State Physics, Johannes Kepler Universität, Linz (Austria); Müller Gubler, E. [Electron Microscopy ETH Zurich, ETH Zurich, Wolfgang-Pauli-Str. 16, CH-8093 Zurich (Switzerland)] [Electron Microscopy ETH Zurich, ETH Zurich, Wolfgang-Pauli-Str. 16, CH-8093 Zurich (Switzerland)

    2013-09-30T23:59:59.000Z

    The electrical conductivity, Seebeck coefficients, and thermal conductivities of a range of p-type Ge/Si{sub 0.5}Ge{sub 0.5} superlattices designed for thermoelectric generation and grown by low energy plasma enhanced chemical vapor deposition have been measured using a range of microfabricated test structures. For samples with barriers around 0.5 nm in thickness, the measured Seebeck coefficients were comparable to bulk p-SiGe at similar doping levels suggesting the holes see the material as a random bulk alloy rather than a superlattice. The Seebeck coefficients for Ge quantum wells of 2.85 ± 0.85 nm increased up to 533 ± 25 ?V/K as the doping was reduced. The thermal conductivities are between 4.5 to 6.0 Wm{sup ?1}K{sup ?1} which are lower than comparably doped bulk Si{sub 0.3}Ge{sub 0.7} but higher than undoped Si/Ge superlattices. The highest measured figure of merit ZT was 0.080 ± 0.011 obtained for the widest quantum well studied. Analysis suggests that interface roughness is presently limiting the performance and a reduction in the strain between the quantum wells and barriers has the potential to improve the thermoelectric performance.