Powered by Deep Web Technologies
Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


1

Thermal Conductivity of Composites Under Di erent Heating Scenarios  

E-Print Network (OSTI)

Thermal Conductivity of Composites Under Di#11;erent Heating Scenarios H.T. Banks #3; , J.H. Hogan of composites under three di#11;erent heating scenarios: (i) a laser pulse heat source, (ii) a preheated composite sample, and (iii) a continuous heat source. 1 Introduction Adhesives such as epoxies, gels

2

Thermally conductive cementitious grout for geothermal heat pump systems  

DOE Patents (OSTI)

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.

Allan, Marita (Old Field, NY)

2001-01-01T23:59:59.000Z

3

eXtremes of heat conduction: Pushing the boundaries of the thermal  

E-Print Network (OSTI)

eXtremes of heat conduction: Pushing the boundaries of the thermal conductivity of materials David. · For example, simplest case of thermal conductivity where resistive scattering dominates C() v() l() d C for the highest thermal conductivity any material (higher conductivity than diamond) Yu et al. (2005) Maruyama

Braun, Paul

4

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

E-Print Network (OSTI)

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.

Debasish Chaudhuri; Abhishek Chaudhuri; Surajit Sengupta

2006-11-14T23:59:59.000Z

5

Experimental investigation of plastic finned-tube heat exchangers, with emphasis on material thermal conductivity  

SciTech Connect

In this paper, two modified types of polypropylene (PP) with high thermal conductivity up to 2.3 W/m K and 16.5 W/m K are used to manufacture the finned-tube heat exchangers, which are prospected to be used in liquid desiccant air conditioning, heat recovery, water source heat pump, sea water desalination, etc. A third plastic heat exchanger is also manufactured with ordinary PP for validation and comparison. Experiments are carried out to determine the thermal performance of the plastic heat exchangers. It is found that the plastic finned-tube heat exchanger with thermal conductivity of 16.5 W/m K can achieve overall heat transfer coefficient of 34 W/m{sup 2} K. The experimental results are compared with calculation and they agree well with each other. Finally, the effect of material thermal conductivity on heat exchanger thermal performance is studied in detail. The results show that there is a threshold value of material thermal conductivity. Below this value improving thermal conductivity can considerably improve the heat exchanger performance while over this value improving thermal conductivity contributes very little to performance enhancement. For the finned-tube heat exchanger designed in this paper, when the plastic thermal conductivity can reach over 15 W/m K, it can achieve more than 95% of the titanium heat exchanger performance and 84% of the aluminum or copper heat exchanger performance with the same dimension. (author)

Chen, Lin; Li, Zhen; Guo, Zeng-Yuan [Department of Engineering Mechanics, Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Tsinghua University, Beijing 100084 (China)

2009-07-15T23:59:59.000Z

6

Temperature, thermal-conductivity, and heat-flux data,Raft River area,  

Open Energy Info (EERE)

Temperature, thermal-conductivity, and heat-flux data,Raft River area, Temperature, thermal-conductivity, and heat-flux data,Raft River area, Cassia County, Idaho (1974-1976) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Report: Temperature, thermal-conductivity, and heat-flux data,Raft River area, Cassia County, Idaho (1974-1976) Details Activities (1) Areas (1) Regions (0) Abstract: Basin and Range Province; Cassia County Idaho; economic geology; exploration; geophysical surveys; geothermal energy; heat flow; heat flux; Idaho; North America; Raft River basin; south-central Idaho; surveys; temperature; thermal conductivity; United States; USGS Author(s): Urban, T.C.; Diment, W.H.; Nathenson, M.; Smith, E.P.; Ziagos, J.P.; Shaeffer, M.H. Published: Open-File Report - U. S. Geological Survey, 1/1/1986 Document Number: Unavailable

7

The self-heating of damp cellulosic materials: I. High thermal conductivity and diffusivity  

Science Journals Connector (OSTI)

......self-heating of damp cellulosic materials: I. High thermal conductivity...stockpiles of cellulosic materials are analysed. The model...distinct bifurcation diagrams. In particular it is...stockpile sizes for materials prone to self-heating...surfaces by breakage on handling. In such circumstances......

R. A. SISSON; A. SWIFT; G. C. WAKE; B. F. GRAY

1992-01-01T23:59:59.000Z

8

Thermal conductivity and specific heat of sorghum grain  

E-Print Network (OSTI)

Formation of Test Canister Ice Jacket ~ Sealing Test Canister in Calorimeter. . 43 44 Testing of Samples. Initial Calorimeter Observations. 49 Insertion of Grain Samples into Calorimeter. . . . 50 Final Test Observations Processing of Data. 54... to Contain the Grain Sample 38 for the Determination of Specific Heat 39 12. Top View of Calorimeter. 40 13. Galvanized Iron Cylinder Used to Form the Ice Jacket Around the Test Canister 42 VIII Figures 14. Clamping Device Used to Hold Test Canister...

Miller, Clinton Frank

2012-06-07T23:59:59.000Z

9

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

SciTech Connect

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.

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

2013-06-01T23:59:59.000Z

10

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

E-Print Network (OSTI)

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...

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

2006-01-01T23:59:59.000Z

11

Determination of thermal conductivity and formation temperature from cooling history of friction-heated probes  

Science Journals Connector (OSTI)

......of geothermal gradient and thermal conductivity of rocks or sediments...the formation temperature and thermal conductivity. Ideally, to...measurements require extra battery power supply and an additional...cooling curve for deducing the thermal properties has been contemplated......

Tien-Chang Lee; A. D. Duchkov; S. G. Morozov

2003-02-01T23:59:59.000Z

12

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

SciTech Connect

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.

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

2014-05-12T23:59:59.000Z

13

Transport properties, specific heat and thermal conductivity of GaN nanocrystalline ceramic  

SciTech Connect

The structural and transport properties (resistivity, thermopower and Hall effect), specific heat and thermal conductivity have been measured for GaN nanocrystalline ceramic prepared by hot pressing. It was found that the temperature dependence of resistivity in temperature range 10-300 K shows the very low activation energy, which is ascribed to the shallow donor doping originating in amorphous phase of sample. The major charge carriers are electrons, what is indicated by negative sign of Hall constant and Seebeck coefficient. The thermopower attains large values (-58 {mu}V/K at 300 K) and was characterized by linear temperature dependence which suggests the diffusion as a major contribution to Seebeck effect. The high electron concentration of 1.3x10{sup 19} cm{sup -3} and high electronic specific heat coefficient determined to be 2.4 mJ/molK{sup 2} allow to conclude that GaN ceramic demonstrates the semimetallic-like behavior accompanied by very small mobility of electrons ({approx}0.1 cm{sup 2}/V s) which is responsible for its high resistivity. A low heat conductivity of GaN ceramics is associated with partial amorphous phase of GaN grains due to high pressure sintering. - Graphical Abstract: Thermal resistivity and thermopower measurements indicates the high phonon scattering and lack of phonon-drag contribution to thermopower in GaN nanoceramics pressed under 4 GPa at 800 {sup o}C.

Sulkowski, Czeslaw [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw (Poland); ChuchmaLa, Andrzej, E-mail: andrzej.chuchmala@pwr.wroc.p [Wroclaw University of Technology, Institute of Electrical Engineering Fundamentals (I7), Wybrzeze Wyspianskiego 27, 50-370 Wroclaw (Poland); Zaleski, Andrzej J.; Matusiak, Marcin; Mucha, Jan; GLuchowski, PaweL; Strek, WiesLaw [Institute of Low Temperature and Structure Research, Polish Academy of Sciences, P.O. Box 1410, 50-950 Wroclaw (Poland)

2010-10-15T23:59:59.000Z

14

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

SciTech Connect

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.

Cable, William; Romanovsky, Vladimir

2014-03-31T23:59:59.000Z

15

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

DOE Data Explorer (OSTI)

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.

Cable, William; Romanovsky, Vladimir

16

Thermally conductive cementitious grouts for geothermal heat pumps. Progress report FY 1998  

SciTech Connect

Research commenced in FY 97 to determine the suitability of superplasticized cement-sand grouts for backfilling vertical boreholes used with geothermal heat pump (GHP) systems. The overall objectives were to develop, evaluate and demonstrate cementitious grouts that could reduce the required bore length and improve the performance of GHPs. This report summarizes the accomplishments in FY 98. The developed thermally conductive grout consists of cement, water, a particular grade of silica sand, superplasticizer and a small amount of bentonite. While the primary function of the grout is to facilitate heat transfer between the U-loop and surrounding formation, it is also essential that the grout act as an effective borehole sealant. Two types of permeability (hydraulic conductivity) tests was conducted to evaluate the sealing performance of the cement-sand grout. Additional properties of the proposed grout that were investigated include bleeding, shrinkage, bond strength, freeze-thaw durability, compressive, flexural and tensile strengths, elastic modulus, Poisson`s ratio and ultrasonic pulse velocity.

Allan, M.L.; Philippacopoulos, A.J.

1998-11-01T23:59:59.000Z

17

On the heat flux vector for flowing granular materials--Part I: effective thermal conductivity and background  

SciTech Connect

Heat transfer plays a major role in the processing of many particulate materials. The heat flux vector is commonly modelled by the Fourier’s law of heat conduction and for complex materials such as nonlinear fluids, porous media, or granular materials, the coeffcient of thermal conductivity is generalized by assuming that it would depend on a host of material and kinematical parameters such as temperature, shear rate, porosity or concentration, etc. In Part I, we will give a brief review of the basic equations of thermodynamics and heat transfer to indicate the importance of the modelling of the heat flux vector. We will also discuss the concept of effective thermal conductivity (ETC) in granular and porous media. In Part II, we propose and subsequently derive a properly frame-invariant constitutive relationship for the heat flux vector for a (single phase) flowing granular medium. Standard methods in continuum mechanics such as representation theorems and homogenization techniques are used. It is shown that the heat flux vector in addition to being proportional to the temperature gradient (the Fourier’s law), could also depend on the gradient of density (or volume fraction), and D (the symmetric part of the velocity gradient) in an appropriate manner. The emphasis in this paper is on the idea that for complex non-linear materials it is the heat flux vector which should be studied; obtaining or proposing generalized form of the thermal conductivity is not always appropriate or suffcient.

Massoudi, Mehrdad

2006-09-10T23:59:59.000Z

18

Nonlinear Electron Heat Conduction Equation and Self similar method for 1-D Thermal Waves in Laser Heating of Solid Density DT Fuel  

E-Print Network (OSTI)

Electron heat conduction is one of the ways that energy transports in laser heating of fusible target material. The aim of Inertial Confinement Fusion (ICF) is to show that the thermal conductivity is strongly dependent on temperature and the equation of electron heat conduction is a nonlinear equation. In this article, we solve the one-dimensional (1-D) nonlinear electron heat conduction equation with a self-similar method (SSM). This solution has been used to investigate the propagation of 1-D thermal wave from a deuterium-tritium (DT) plane source which occurs when a giant laser pulse impinges onto a DT solid target. It corresponds to the physical problem of rapid heating of a boundary layer of material in which the energy of laser pulse is released in a finite initial thickness.

A. Mohammadian Pourtalari; M. A. Jafarizadeh; M. Ghoranneviss

2011-05-22T23:59:59.000Z

19

Heat Transfer -1 You are given the following information for a fluid with thermal conductivity of k = 0.0284 W/m-K that  

E-Print Network (OSTI)

Heat Transfer - 1 You are given the following information for a fluid with thermal conductivity the flow is laminar near the wall. a) (30 points) Determine the corresponding heat transfer coefficient the heat transfer coefficient as a function of x. c) (25 points) Determine the average heat transfer

Virginia Tech

20

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

DOE Patents (OSTI)

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.

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

1985-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


21

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

DOE Patents (OSTI)

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.

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

1983-05-03T23:59:59.000Z

22

NANO REVIEW Open Access Thermal conductivity and thermal boundary  

E-Print Network (OSTI)

NANO REVIEW Open Access Thermal conductivity and thermal boundary resistance of nanostructures and the thermal transport prop- erties is a key point to design materials with preferred thermal properties with the heat dissipation on them. The influence of the interfacial roughness on the thermal conductivity

Boyer, Edmond

23

Heat dissipation performance of a high-brightness LED package assembly using high-thermal conductivity filler  

Science Journals Connector (OSTI)

This paper presents a thermal analysis and experimental validation of natural convective heat transfer of a high-brightness light-emitting diode (LED) package assembly. The substrate...

Yung, K C; Liem, H; Choy, H S

2013-01-01T23:59:59.000Z

24

Thermal shock resistance of solids associated with hyperbolic heat conduction theory  

Science Journals Connector (OSTI)

...damage. Examples are as varied as energy conversion systems, electronic devices and...that was coupled with the local energy balance-[21,22]. Since then...frequency of the molecules within the energy carrier. The thermal relaxation time...

2013-01-01T23:59:59.000Z

25

In-Situ Thermal Conductivity Testing Using a Portable Heat Flow Meter  

E-Print Network (OSTI)

A method has been developed for measuring heat losses from insulated systems in the field. While the measurements are not as precise as those made under laboratory conditions, they are more indicative of actual in service conditions. Extensive field...

Harr, K. S.; Hutto, F. B., Jr.

1979-01-01T23:59:59.000Z

26

THERMALLY CONDUCTIVE CEMENTITIOUS GROUTS FOR GEOTHERMAL HEAT PUMPS. PROGRESS REPORT BY 1998  

SciTech Connect

Research commenced in FY 97 to determine the suitability of superplasticized cement-sand grouts for backfilling vertical boreholes used with geothermal heat pump (GHP) systems. The overall objectives were to develop, evaluate and demonstrate cementitious grouts that could reduce the required bore length and improve the performance of GHPs. This report summarizes the accomplishments in FY 98.

ALLAN,M.L.; PHILIPPACOPOULOS,A.J.

1998-11-01T23:59:59.000Z

27

Determination of thermal conductivity and formation temperature from cooling history of friction-heated probes  

Science Journals Connector (OSTI)

......dissipation at the rising cost of ship operational time...penetrations for measurements of geothermal gradients at closely...paves the way at no extra cost for the determination...imposing heat flow as an energy constraint in transient...typical measurement of geothermal gradient in the ocean......

Tien-Chang Lee; A. D. Duchkov; S. G. Morozov

2003-02-01T23:59:59.000Z

28

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...

29

Experimental thermal conductivity and contact conductance of graphite composites  

E-Print Network (OSTI)

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...

Jackson, Marian Christine

2012-06-07T23:59:59.000Z

30

HEATS: Thermal Energy Storage  

SciTech Connect

HEATS Project: The 15 projects that make up ARPA-E’s HEATS program, short for “High Energy Advanced Thermal Storage,” seek to develop revolutionary, cost-effective ways to store thermal energy. HEATS focuses on 3 specific areas: 1) developing high-temperature solar thermal energy storage capable of cost-effectively delivering electricity around the clock and thermal energy storage for nuclear power plants capable of cost-effectively meeting peak demand, 2) creating synthetic fuel efficiently from sunlight by converting sunlight into heat, and 3) using thermal energy storage to improve the driving range of electric vehicles (EVs) and also enable thermal management of internal combustion engine vehicles.

None

2012-01-01T23:59:59.000Z

31

Low Conductivity Thermal Barrier Coatings  

E-Print Network (OSTI)

Low Conductivity Thermal Barrier Coatings A Dissertation Presented to The Faculty of the School conductivity of the coatings. The minimum thermal conductivity occurs at a low rotation rate and is 0.8 W intrinsic thermal conductivity, good phase stability and greater resistance to sintering and CMAS attack

Wadley, Haydn

32

Enhanced Thermal Conductivity Oxide Fuels  

SciTech Connect

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.

Alvin Solomon; Shripad Revankar; J. Kevin McCoy

2006-01-17T23:59:59.000Z

33

Effect of neutral collision and radiative heat-loss function on self-gravitational instability of viscous thermally conducting partially-ionized plasma  

SciTech Connect

The problem of thermal instability and gravitational instability is investigated for a partially ionized self-gravitating plasma which has connection in astrophysical condensations. We use normal mode analysis method in this problem. The general dispersion relation is derived using linearized perturbation equations of the problem. Effects of collisions with neutrals, radiative heat-loss function, viscosity, thermal conductivity and magnetic field strength, on the instability of the system are discussed. The conditions of instability are derived for a temperature-dependent and density-dependent heat-loss function with thermal conductivity. Numerical calculations have been performed to discuss the effect of various physical parameters on the growth rate of the gravitational instability. The temperature-dependent heat-loss function, thermal conductivity, viscosity, magnetic field and neutral collision have stabilizing effect, while density-dependent heat-loss function has a destabilizing effect on the growth rate of the gravitational instability. With the help of Routh-Hurwitz's criterion, the stability of the system is discussed.

Kaothekar, Sachin [School of Studies in Physics, Vikram University, Ujjain-456010, Madhya Pradesh (India); Department of Physics, Mahakal Institute of Technology, Ujjain-456664, Madhya Pradesh (India); Soni, Ghanshyam D. [Government Girls Degree College, Dewas, Madhya Pradesh (India); Chhajlani, Rajendra K. [School of Studies in Physics, Vikram University, Ujjain-456010, Madhya Pradesh (India)

2012-12-15T23:59:59.000Z

34

Fibrous heat-insulation materials use of the hot wire method to determine thermal conductivity of fibrous heat-insulation materials  

Science Journals Connector (OSTI)

It is desirable to determine the thermal conductivity of materials in the form of plates 30–40 mm thick or of a layer of wool of the same thickness by the hot wire method throughout their service temperature r...

Ya. A. Landa; E. Ya. Litovskii; B. S. Glazachev

35

Cylindrical thermal contact conductance  

E-Print Network (OSTI)

of the Mahr-Federal, Inc. respectively facilitated and provided the necessary surface metrology data of the test pieces. Mr. Claude Davis of Corning, Inc. obtained the thermophysical properties of the Ultra Low Expansion Titanium Silicate glass used... as thermal expansion standard. The engineers at National Instruments provided some much-needed advice and software for programming the data acquisition system. The TAMU Physics Machine Shop provided design advice and a couple of last...

Ayers, George Harold

2004-09-30T23:59:59.000Z

36

Thermal Conductivity of High-Modulus Polymer Fibers Xiaojia Wang,*,  

E-Print Network (OSTI)

to be the dominate carriers of heat. 1. INTRODUCTION Polymeric materials typically have a low thermal conductivity transfer is critical are often limited by low thermal conductivity. Here, we leverage the enormous research and low-density PE with varying fiber volume fractions.11 They reported an axial thermal conductivity

Cahill, David G.

37

Effective Thermal Conductivity of Graded Nanocomposites with Interfacial Thermal  

E-Print Network (OSTI)

.M. Yin", G. H. Paulino", W.G. Buttlar", and L.Z. Sun'' '^Department of Civil and Environmental the effective thermal conductivity distribution in functionally graded materials (FGMs) considering the Kapitza is developed to derive the averaged heat flux field of the particle phase. Then the temperature gradient can

Paulino, Glaucio H.

38

Continuous Processing of High Thermal Conductivity Polyethylene...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Processing of High Thermal Conductivity Polyethylene Fibers and Sheets Continuous Processing of High Thermal Conductivity Polyethylene Fibers and Sheets Massachusetts Institute of...

39

Domestic Heating and Thermal Insulation  

Science Journals Connector (OSTI)

... DIGEST 133 of the Building Research Station, entitled "Domestic Heating and Thermal Insulation" (Pp. 7. London : H.M. Stationery Office, 1960. 4insulation, the standard of heating, the ventilation-rate and the length of the heating season ...

1960-09-17T23:59:59.000Z

40

Thermal conductivity of a kinetic ising model  

Science Journals Connector (OSTI)

Using a novel extension of the microcanonical Monte Carlo algorithm, we have simulated the behavior of a two-dimensional nearest-neighbor ferromagnetic Ising model in the presence of a temperature gradient. The technique consists of setting the temperatures of boundary spins, while allowing "demons" associated with the other sites to control heat transfer. We demonstrate that our system is in local thermodynamic equilibrium, and compute the thermal conductivity as a function of temperature.

R. Harris and Martin Grant

1988-11-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


41

Thermal Conductivity of Polycrystalline Semiconductors and Ceramics  

E-Print Network (OSTI)

semiconductors and ceramics with desired thermalthermal conductivity of several polycrystalline semiconductors and ceramics,Thermal Conductivity of Polycrystalline Semiconductors and Ceramics

Wang, Zhaojie

2012-01-01T23:59:59.000Z

42

Reduced Thermal Conductivity of Compacted Silicon Nanowires  

E-Print Network (OSTI)

Thermal-Barrier-Coating Applications,” Journa of American Ceramicthermal conductivity materials are typically found among ceramicsThermal Conductivity of Porous Materials: Application to Thick Barrier Coatings,” Journal of the European Ceramic

Yuen, Taylor S.

43

Thermal Conductivity and Noise Attenuation in  

E-Print Network (OSTI)

.3.4 Corrosion-resistant and high-temperature filters 9 1.3.5 Acoustic Applications 9 2. THERMAL CONDUCTIVITY 2.1 THERMAL RESISTANCE 2.1.1 Thermal Conductors in Series 12 2.1.2 Thermal conductors in parallel 13 2 difference RTH Thermal resistance of conductor sb Stefan's constant T4 Temperature difference K* Total

Cambridge, University of

44

Solar Thermal Process Heat | Open Energy Information  

Open Energy Info (EERE)

Solar Thermal Process Heat Incentives Retrieved from "http:en.openei.orgwindex.php?titleSolarThermalProcessHeat&oldid267198" Category: Articles with outstanding TODO tasks...

45

Thermal History of the Earth with consideration of the Variable Thermal Conductivity of its Mantle  

Science Journals Connector (OSTI)

......the data about electric conductivity...give no thermal resistance and the integral...the number of elementary cells in I cm3...of heat in an elementary volume v k cm3...inverse to the resistances:the thermal...the hydraulic resistance determining...charge,h-electric conductivity......

H. A. Lubimova

1958-06-01T23:59:59.000Z

46

Polymer Nanofibers with Outstanding Thermal Conductivity and Thermal Stability: Fundamental Linkage between Molecular Characteristics and Macroscopic Thermal Properties  

E-Print Network (OSTI)

Polymer nanofibers with high thermal conductivities and outstanding thermal stabilities are highly desirable in heat transfer-critical applications such as thermal management, heat exchangers and energy storage. In this work, we unlock the fundamental relations between the thermal conductivity and thermal stability of polymer nanofibers and their molecular characteristics by studying the temperature-induced phase transitions and thermal transport of a series of polymer nanofibers. Ten different polymer nanofibers with systematically chosen molecular structures are studied using large scale molecular dynamics simulations. We found that high thermal conductivity and good thermal stability can be achieved in polymers with rigid backbones, exemplified by {\\pi}-conjugated polymers, due to suppressed segmental rotations and large phonon group velocities. The low probability of segmental rotation does not only prevent temperature-induced phase transition but also enables long phonon mean free paths due to reduced di...

Zhang, Teng; Luo, Tengfei

2014-01-01T23:59:59.000Z

47

M. Bahrami ENSC 388 (F09) Steady Conduction Heat Transfer 1 Steady Heat Conduction  

E-Print Network (OSTI)

resistance of the wall. The heat transfer across the fluid/solid interface is based on Newton's law M. Bahrami ENSC 388 (F09) Steady Conduction Heat Transfer 1 Steady Heat Conduction In thermodynamics, we considered the amount of heat transfer as a system

Bahrami, Majid

48

Process for fabricating composite material having high thermal conductivity  

DOE Patents (OSTI)

A process 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.

Colella, Nicholas J. (Livermore, CA); Davidson, Howard L. (San Carlos, CA); Kerns, John A. (Livermore, CA); Makowiecki, Daniel M. (Livermore, CA)

2001-01-01T23:59:59.000Z

49

E-Print Network 3.0 - anomalous heat conduction Sample Search...  

NLE Websites -- All DOE Office Websites (Extended Search)

University, Stanford, California, January 31 -February 2, 2011 Summary: conductive heat loss outside the main areas of thermally anomalous ground, and nor have discharges...

50

A study of temperature distributions due to conduction reservoir heating  

E-Print Network (OSTI)

of thermal conductivity with temperature. He showed this effect could be very important in considering a material such as oil shale, where the conductivity of the raw shale may be five times as great as that of the spent shale. Neglecting this variation... conduction model to investigate the in place heating of oil shale by hot gases forced through a fracture. The heat injection rate he considered is much less than would normally be employed for steam injection into permeable reservoirs and is only about...

Connaughton, Charles Richard

2012-06-07T23:59:59.000Z

51

Experimental investigation of high temperature thermal contact resistance between high thermal conductivity C/C material and Inconel 600  

Science Journals Connector (OSTI)

Abstract Thermal contact resistance at the assembly interface plays an important role in high temperature structure design and safety assessment. Thermal contact resistance between high thermal conductivity C/C material and superalloy Inconel 600 was experimentally investigated in the present paper. They are widely used in thermal protection structures of heat-pipe-cooled leading edges to enhance interface heat transfer. Results showed that thermal contact resistance between the two materials is about 5 × 10?5 m2 K/W, and it is necessary to take into account the effect of the thermal contact resistance in high thermal conductivity C/C material related thermal structure design.

Donghuan Liu; Yan Luo; Xinchun Shang

2015-01-01T23:59:59.000Z

52

Electrical and thermal conductivities in dense plasmas  

SciTech Connect

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.

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

53

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

SciTech Connect

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.

Nguyen, Ba Nghiep; Henager, Charles H.

2013-04-20T23:59:59.000Z

54

Thermal Conductivity in Nanocrystalline Ceria Thin Films  

SciTech Connect

The thermal conductivity of nanocrystalline ceria films grown by unbalanced magnetron sputtering is determined as a function of temperature using laser-based modulated thermoreflectance. The films exhibit significantly reduced conductivity compared with stoichiometric bulk CeO2. A variety of microstructure imaging techniques including X-ray diffraction, scanning and transmission electron microscopy, X-ray photoelectron analysis, and electron energy loss spectroscopy indicate that the thermal conductivity is influenced by grain boundaries, dislocations, and oxygen vacancies. The temperature dependence of the thermal conductivity is analyzed using an analytical solution of the Boltzmann transport equation. The conclusion of this study is that oxygen vacancies pose a smaller impediment to thermal transport when they segregate along grain boundaries.

Marat Khafizov; In-Wook Park; Aleksandr Chernatynskiy; Lingfeng He; Jianliang Lin; John J. Moore; David Swank; Thomas Lillo; Simon R. Phillpot; Anter El-Azab; David H. Hurley

2014-02-01T23:59:59.000Z

55

Ultralow Thermal Conductivity in Organoclay Nanolaminates Synthesized via Simple Self-Assembly  

E-Print Network (OSTI)

transform fully dense solids into ultralow thermal conductivity materials. Here we report a simple self of nanolaminate spacing. A simple series resistance model describes the behavior and gives an interfacial thermal thermal conductance For phonon-mediated heat conduction, a material is generally thought to reach its

Braun, Paul

56

Thermal Conductance of Thin Silicon Nanowires  

Science Journals Connector (OSTI)

The thermal conductance of individual single crystalline silicon nanowires with diameters less than 30 nm has been measured from 20 to 100 K. The observed thermal conductance shows unusual linear temperature dependence at low temperatures, as opposed to the T3 dependence predicted by the conventional phonon transport model. In contrast to previous models, the present study suggests that phonon-boundary scattering is highly frequency dependent, and ranges from nearly ballistic to completely diffusive, which can explain the unexpected linear temperature dependence.

Renkun Chen, Allon I. Hochbaum, Padraig Murphy, Joel Moore, Peidong Yang, and Arun Majumdar

2008-09-02T23:59:59.000Z

57

Some Remarks on Lattice Thermal Conductivity  

Science Journals Connector (OSTI)

The problem of lattice thermal conductivity (in an insulator) has been outstanding for many years. Debye and Peierls made fundamental contributions in relating finite thermal conductivity to anharmonic interactions between the normal modes of lattice vibration; detailed analysis and calculation however remains today a difficult problem. This paper presents a rather crude and elementary discussion of the problem for “classical” temperatures (T??) which yields a semiquantitative result in agreement with other workers. We are also able to make a rather direct estimate of the probable magnitude of the contribution to the thermal resistivity which arises from the quartic term in the lattice potential.

D. K. C. MacDonald

1960-01-01T23:59:59.000Z

58

Thermal conductance of metal-metal interfaces  

Science Journals Connector (OSTI)

The thermal conductance of interfaces between Al and Cu is measured in the temperature range 78thermal conductance of the as-deposited Al-Cu interface is 4GWm?2K?1 at room temperature, an order-of-magnitude larger than the phonon-mediated thermal conductance of typical metal-dielectric interfaces. The magnitude and the linear temperature dependence of the conductance are described well by a diffuse-mismatch model for electron transport at interfaces.

Bryan C. Gundrum; David G. Cahill; Robert S. Averback

2005-12-30T23:59:59.000Z

59

Heat conduction of single-walled carbon nanotube isotope-superlattice structures: A molecular dynamics study  

E-Print Network (OSTI)

-folding effect to thermal boundary resistance of lattice interface. The crossover mechanism is explained-dimensional materials. In our previous molecular dynamics study, isotope-effects on the thermal conduction were of heat conduction of SWNTs subjected to nanoscale intrinsic thermal resistances. Here, in order to reduce

Maruyama, Shigeo

60

Molecular Dynamic Study of Thermal Conductivity of Amorphous Nanoporous Silica  

E-Print Network (OSTI)

as a thermal isolation layer”. Ceramics International, 34(Thermal conductivity of highly porous zirconia”. Journal of the European Ceramic

Coquil, Thomas; Fang, Jin; Pilon, Laurent

2011-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


61

Heat conductivity of a pion gas  

E-Print Network (OSTI)

We evaluate the heat conductivity of a dilute pion gas employing the Uehling-Uehlenbeck equation and experimental phase-shifts parameterized by means of the SU(2) Inverse Amplitude Method. Our results are consistent with previous evaluations. For comparison we also give results for an (unphysical) hard sphere gas.

Antonio Dobado Gonzalez; Felipe J. Llanes-Estrada; Juan M. Torres Rincon

2007-02-13T23:59:59.000Z

62

INFLUENCE OF ANISOTROPIC THERMAL CONDUCTIVITY IN THE APPARATUS INSULATION FOR SUBLIMATION GROWTH OF SIC  

E-Print Network (OSTI)

INFLUENCE OF ANISOTROPIC THERMAL CONDUCTIVITY IN THE APPARATUS INSULATION FOR SUBLIMATION GROWTH insulation for sublimation growth of SiC: Numerical investigation of heat transfer J¨urgen Geiser, Olaf Klein). As it is not unusual for the thermal insulation of PVT growth apparatus to possess an anisotropic thermal conductivity

63

IEEE TRANSACTIONS ON COMPONENTS AND PACKAGING TECHNOLOGIES, VOL. 25, NO. 4, DECEMBER 2002 615 In-Plane Effective Thermal Conductivity of  

E-Print Network (OSTI)

material. Thermal conductivity of second phase material. . . Heat flux. Mesh numbers along. Effective thermal resistance. Thermal diffusivity. Specific surface area. Porosity. Time. Manuscript effect, the effective thermal conductivity of these materials, is relatively small, so that much

Wirtz, Richard A.

64

Continuous Processing of High Thermal Conductivity Fibers and...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

We are developing a continuous fabrication process for high thermal conductivity polyethylene (PE) films While high thermal conductivity in (PE) has been shown in isolated...

65

Nanoscale thermal transport and the thermal conductance of interfaces  

E-Print Network (OSTI)

-8 2008 #12;Er-fiber laser system, UIUC Nov. 2007 #12;Solid-liquid interfaces: Two approaches · Transient-wide: ­ thermal interface materials ­ so-called "nanofluids" (suspensions in liquids) ­ polymer composites absorption depends on temperature of the nanotube · Assume heat capacity is comparable to graphite · Cooling

Braun, Paul

66

Thermal conductivity of low density carbon aerogels  

Science Journals Connector (OSTI)

Carbon aerogels with densities ranging from 0.182 to 0.052 g/cm3, pore sizes ranging from 88 to 227 nm, and particle diameters ranging from 20 to 13 nm were prepared. Thermal conductivity measurements by laser fl...

Junzong Feng; Jian Feng; Changrui Zhang

2012-10-01T23:59:59.000Z

67

The Thermal Conductivity of Low Density Concretes Containing Perlite  

E-Print Network (OSTI)

-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...

Yarbrough, D. W.

68

Measurement of thermal conductivity P t BPart B  

E-Print Network (OSTI)

wave Take the Fourier transform of this frequency domain solution #12;For a low thermal conductivity thin filmFor a low thermal conductivity thin film on a high thermal conductivity substrate (Factor of 2Measurement of thermal conductivity Part A: P t BPart B: · Time domain thermoreflectance #12

Braun, Paul

69

Developing a High Thermal Conductivity Fuel with Silicon Carbide Additives  

SciTech Connect

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:

Ronald baney; James Tulenko

2012-11-20T23:59:59.000Z

70

Enhancing Thermal Conductivity and Reducing Friction  

NLE Websites -- All DOE Office Websites (Extended Search)

Laboratory currently has several projects underway to develop advanced fluids, films, coatings, and Laboratory currently has several projects underway to develop advanced fluids, films, coatings, and processes to improve thermal conductivity and reduce friction. These measures are helping to increase energy efficiency for next-generation transportation applications. Superhard and Slick Coating (SSC) Opportunity: Friction, wear, and lubrication strongly affect the energy efficiency, durability, and environmental compatibility of

71

Design of a novel conduction heating based stress-thermal cycling apparatus for composite materials and its utilization to characterize composite microcrack damage thresholds  

E-Print Network (OSTI)

???????????..?????????47 viii CHAPTER Page 4.4 Thermal Loading Combined with Bending Conditions?????? 49 4.5 Thermo-Viscoelastic Constitutive....1 Characterization of Crack Formation and Propagation Mechanism?. 93 6.2 Analytical Study of Time Dependent Non-Isothermal Linear Thermo-Viscoelasticity??????????????????...94 6.3 Initial Damage Characterization??????????????.. 101 6.3.1 Cryogenic Temperature...

Ju, Jaehyung

2006-10-30T23:59:59.000Z

72

An analog analysis of transient heat flow in solids with temperature-dependent thermal properties  

E-Print Network (OSTI)

) used a nonlinear material known as Metrosil to simulate the nonlinear variations of thermal properties for combined conductive and radiant heat transfer. Since that time, Friedmann (8) has used nonlinear resistances in conjunction with an electronic... at end of this thesis. K = thermal conductivity of heat conducting media, and K and S are functions of the temperature t. Since the formation of these equations, solutions of transient heat flow problems involving materials in which the thermal...

Lee, Dwain Edward

2012-06-07T23:59:59.000Z

73

Testing the physics of heat conduction using high pressure: crystals, glasses, and interfaces  

E-Print Network (OSTI)

, simplest case of thermal conductivity where resistive scattering dominates C() v() l() d C() = heatTesting the physics of heat conduction using high pressure: crystals, glasses, and interfaces David supported by CDAC and AFOSR #12;The story... · Use high pressure (gem anvil cells) to modify vibrational

Braun, Paul

74

Spring 2005 Test #1 1. Steady state heat conduction in a slab with heat generation. (40 points)  

E-Print Network (OSTI)

and goes only in the r direction. The fluid density is , the heat capacity is Cp and the thermal to the surroundings is given by a heat transfer coefficient and Newton's law of cooling q(R) = h (T(R) -T0). a. WriteChEg 356 Spring 2005 Test #1 2/17/05 1. Steady state heat conduction in a slab with heat generation

McCready, Mark J.

75

Electrical resistivity and thermal conductivity of liquid Fe alloys at high P and T, and  

E-Print Network (OSTI)

Electrical resistivity and thermal conductivity of liquid Fe alloys at high P and T, and heat flux to crystallize (1, 4). Existing estimates of thermal conductivity (kel) and electrical resistivity (el) of Earth of electrical resistivity to temperature, its invariability along and across the Fe liquidus, and adherence

Steinle-Neumann, Gerd

76

Ultralow thermal conductivity and the thermal d t f i t fconductance of interfaces  

E-Print Network (OSTI)

are critical at the nanoscale · Low thermal conductivity in nanostructured materials ­ improved thermoelectric to the thermal conductivity of materials. · Ultralow thermal conductivity: beating the amorphous limitUltralow thermal conductivity and the thermal d t f i t fconductance of interfaces David G. Cahill

Braun, Paul

77

An Analytical Model for Determining the Thermal Conductivity of Closed-Cell Foam Insulation  

Science Journals Connector (OSTI)

The purpose of this paper is to present analytical methods and some preliminary test results for determining the thermal conductivity and net heat flow in closed-cell foam materials used as cryogenic insulation. ...

M. B. Hammond Jr.

1995-01-01T23:59:59.000Z

78

Reduction of thermal conductivity of anharmonic lattices Lei Wang1 and Baowen Li1,2,3,  

E-Print Network (OSTI)

for constructing a material with ultra low thermal conductivity is still not available. As a simple. INTRODUCTION Thermal conductivity is one of the most fundamental and important properties of materials.1 heat dissipation. In the former case, one needs to have a very low thermal conductivity, while

Li, Baowen

79

CONDUCTION HEAT TRANSFER Dr. Ruhul Amin Fall 2011  

E-Print Network (OSTI)

ME 525 CONDUCTION HEAT TRANSFER Dr. Ruhul Amin Fall 2011 Office: 201C Roberts Hall Lecture Room of conduction heat transfer. Important results which are useful for engineering application will also: 121 Roberts Hall Phone: 994-6295 Lecture Periods: 12:45- 2:00, TR TEXT: Heat Conduction, M. N. Ozisik

Dyer, Bill

80

Strain-controlled thermal conductivity in ferroic twinned films  

E-Print Network (OSTI)

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 ...

Li, Suzhi

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


81

Optimization of the configuration and working fluid for a micro heat pipe thermal control device  

E-Print Network (OSTI)

of a micro heat pipe system containing a working fluid with physical properties having been speciffcally selected such that the heat pipes, as a whole, vary in effective thermal conductance, thereby providing a level of temperature regulation...

Coughlin, Scott Joseph

2006-04-12T23:59:59.000Z

82

Ultralow Thermal Conductivity of Isotope-Doped Silicon Nanowires  

E-Print Network (OSTI)

conductivity of SiNWs is about 2 orders of magnitude smaller than that of bulk crystals.18,19 The low thermal conductivity (0.05 W/m K) found in layered materials.22 So it is indispensable to reduce the thermal conUltralow Thermal Conductivity of Isotope-Doped Silicon Nanowires Nuo Yang, Gang Zhang,*, and Baowen

Li, Baowen

83

Monte Carlo Simulations of Thermal Conductivity in Nanoporous Si Membranes  

E-Print Network (OSTI)

candidates for thermoelectric materials as they can provide extremely low thermal conductivity , relatively of boundary scattering on the thermal conductivity. We show that the material porosity strongly affects1 Monte Carlo Simulations of Thermal Conductivity in Nanoporous Si Membranes Stefanie Wolf1

84

Pushing the boundaries of the thermal conductivity of materials  

E-Print Network (OSTI)

Pushing the boundaries of the thermal conductivity of materials David G. Cahill, C. Chiritescu, Y. · Advances in time-domain thermoreflectance. · Amorphous limit to the thermal conductivity of materials. #12;50 nm Interfaces are critical at the nanoscale · Low thermal conductivity in nanostructured

Braun, Paul

85

Note: Local thermal conductivities from boundary driven non-equilibrium molecular dynamics simulations  

SciTech Connect

We report non-equilibrium molecular dynamics simulations of heat transport in models of molecular fluids. We show that the “local” thermal conductivities obtained from non-equilibrium molecular dynamics simulations agree within numerical accuracy with equilibrium Green-Kubo computations. Our results support the local equilibrium hypothesis for transport properties. We show how to use the local dependence of the thermal gradients to quantify the thermal conductivity of molecular fluids for a wide range of thermodynamic states using a single simulation.

Bresme, F., E-mail: f.bresme@imperial.ac.uk [Department of Chemistry, Chemical Physics Section, Imperial College London, London SW7 2AZ (United Kingdom); Department of Chemistry, Norwegian University of Science and Technology, Trondheim (Norway); Armstrong, J., E-mail: j.armstrong@imperial.ac.uk [Department of Chemistry, Chemical Physics Section, Imperial College London, London SW7 2AZ (United Kingdom)

2014-01-07T23:59:59.000Z

86

Passive Solar Building Design and Solar Thermal Space Heating...  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Passive Solar Building Design and Solar Thermal Space Heating Webinar Passive Solar Building Design and Solar Thermal Space Heating Webinar Watch a recording of National Renewable...

87

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

SciTech Connect

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.

Williams, Colin F.; Sass, John H.

1996-01-24T23:59:59.000Z

88

G-Plus report to Owens Corning-thermal conductivity Measurements of Fiberglass  

SciTech Connect

Fiberglass made by Owens Corning is being used in noise reduction of automobile exhaust system. Specifically, the glass fibers are packed inside the muffler to achieve the desired acoustic effect. A secondary benefit of the fibers is to serve as a thermal insulation. Because of this insulating property, the glass fibers can serve to reduce the temperature of the muffler shell. This in turn reduces the need for heat shields around mufflers and reduces the amount of exterior temperature accelerated corrosion of the muffler shell, especially in the winter ''salt belts'' where large amounts of salt are placed on highways to minimize the safety impact of snow and ice. In addition, for some applications the use of the fiberglass could allow the use of lighter weight carbon based polymer composite materials in place of steel for muffler shells. However, in order to properly design exhaust systems without heat shields or to take advantage of new materials, the thermal conductivity of the fiberglass material at operating temperatures (for some applications above 750 C) must be known. We selected two types of Owens Corning glass fibers, 17 {micro}m and 24 {micro}m in diameter, for this study. There are some room temperature thermal conductivity data for the fiberglass, but high temperature data are not available. Based on the thermal radiation model, thermal conductivity should increase rapidly at high temperature, providing less thermal insulation. In addition, thermal conductivity depends on packing density of the glass fibers. We will study the effect of packing density on thermal conductivity. Another issue is that the glass fiber conducts heat better along the fiber, while the conduction across the fibers is poor, because thermal conduction from one fiber to another has to go through an interface with thermal resistance. In fiberglass, most fibers are not in good contact with the surrounding fibers, thus, most heat transfer is dependent on the thermal radiation effect. Among the many methods of measuring thermal conductivity, only a few can be used for glass fibers. The traditional heat flow meter is used in testing thermal insulations near room temperature. At higher temperatures this method cannot be used due to material and instrument limitations. Our plan is to use a transient plane source (TPS) method to measure thermal conductivity directly. The advantage of the TPS method is that measurements can be taken at over 700 C, and covers the temperature of the automobile exhausts. The following is a report for the G-Plus project conducted at ORNL to apply the TPS method to characterizing the thermal conductivity of two types of fiberglass and also the effect of packing density.

Wang, H

2003-04-15T23:59:59.000Z

89

SHOCKS AND THERMAL CONDUCTION FRONTS IN RETRACTING RECONNECTED FLUX TUBES  

SciTech Connect

We present a model for plasma heating produced by time-dependent, spatially localized reconnection within a flare current sheet separating skewed magnetic fields. The reconnection creates flux tubes of new connectivity which subsequently retract at Alfvenic speeds from the reconnection site. Heating occurs in gas-dynamic shocks (GDSs) which develop inside these tubes. Here we present generalized thin flux tube equations for the dynamics of reconnected flux tubes, including pressure-driven parallel dynamics as well as temperature-dependent, anisotropic viscosity and thermal conductivity. The evolution of tubes embedded in a uniform, skewed magnetic field, following reconnection in a patch, is studied through numerical solutions of these equations, for solar coronal conditions. Even though viscosity and thermal conductivity are negligible in the quiet solar corona, the strong GDSs generated by compressing plasma inside reconnected flux tubes generate large velocity and temperature gradients along the tube, rendering the diffusive processes dominant. They determine the thickness of the shock that evolves up to a steady state value, although this condition may not be reached in the short times involved in a flare. For realistic solar coronal parameters, this steady state shock thickness might be as long as the entire flux tube. For strong shocks at low Prandtl numbers, typical of the solar corona, the GDS consists of an isothermal sub-shock where all the compression and cooling occur, preceded by a thermal front where the temperature increases and most of the heating occurs. We estimate the length of each of these sub-regions and the speed of their propagation.

Guidoni, S. E.; Longcope, D. W., E-mail: guidoni@physics.montana.ed [Department of Physics, Montana State University, Bozeman, MT 59717-3840 (United States)

2010-08-01T23:59:59.000Z

90

October 2011 SDI FEP Issues Heat Conduction Issues (HC)  

E-Print Network (OSTI)

the heaters. Background: Halite thermal conductivity (k) is inversely related to porosity. The higher porosity additional information on the higher temperature-lower thermally conductive nature of halite and its affect on distal temperatures. Background: Halite thermal k is inversely related to temperature. A higher

91

Molecular Dynamics Simulations of Heat Conduction in Nanostructures: Effect of Heat Bath  

E-Print Network (OSTI)

temperature profile and thermal conductivity in homogeneous materials. Furthermore, the thermal rectification) The low thermal conductivity of SiNWs is of particular interest for thermoelectric application.10 point of view. On the one hand, superior thermal conductivity has been observed in graphene1

Li, Baowen

92

SENSIBLE HEAT STORAGE FOR A SOLAR THERMAL POWER PLANT  

E-Print Network (OSTI)

HEAT STORAGE FOR A SOLAR THERMAL POWER PLANT Thomas F.CENTRAL RECEIVER SOLAR THERMAL POWER SYSTEM, PHASE progressCorporation, RECEIVER SOLAR THERMAL POWER SYSTEM, PHASE I,

Baldwin, Thomas F.

2011-01-01T23:59:59.000Z

93

Project Profile: Sensible Heat, Direct, Dual-Media Thermal Energy...  

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

Sensible Heat, Direct, Dual-Media Thermal Energy Storage Module Acciona logo Acciona Solar, under the Thermal Storage FOA, plans to develop a prototype thermal energy storage...

94

Effect of nanofluids on thermal performance of heat pipes.  

E-Print Network (OSTI)

?? A relatively new way for utilizing the thermal performance of heat pipes is to use nanofluids as working fluids in the heat pipes. Heat… (more)

Ferizaj, Drilon

2014-01-01T23:59:59.000Z

95

Duality of the Interfacial Thermal Conductance in Graphene-based Nanocomposites  

SciTech Connect

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.

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

96

Morphology and thermal conductivity of yttria-stabilized zirconia coatings  

E-Print Network (OSTI)

yttria-stabilized zir- conia (YSZ) is then applied to provide thermal insulation [1]. This ceramic layer]. The thermal conductivity of the ceramic layer has been found to depend on the pore morphology within a coatingMorphology and thermal conductivity of yttria-stabilized zirconia coatings Hengbei Zhao a

Wadley, Haydn

97

Effective thermal conductivity for anisotropic granular porous media using fractal concepts  

SciTech Connect

The use of granular porous media in chemical processes, thermal insulation, heat exchangers, and nuclear reactor fuel rods has led to the development of correlations for thermophysical properties, such as thermal conductivity. These correlations are essential in the prediction of heat and mass transfer involving porous media. Analytical correlations are derived for the effective thermal conductivity of anisotropic, Granular Porous Media (GPM). The correlations proposed, which can be apply in general to any porous media material, are used to determine the effective thermal conductivity of GPM that are formed by semi-cylindrical ice particles. Pictures of the cross-section of GPM provide digital data for measuring local fractal dimensions. Local fractal dimensions are used to determine an equivalent three-dimensional Representative Unit Cell (RUC) for the GPM considered. A simplified analysis of heat conduction at the RUC level provide an analytical expression for the effective heat transfer coefficient. Estimates for the effective thermal conductivity by the use of the models are discussed and compared with various models known in literature. Finally, results for anisotropic thermal conductivities, which are obtained by the use of fractal correlations, are discussed.

Sabau, A.S.; Tao, Y.X.; Liu, G.; Vidhuvalavan, G.

1997-07-01T23:59:59.000Z

98

Final Report: Thermal Conductance of Solid-Liquid Interfaces  

SciTech Connect

Research supported by this grant has significantly advanced fundamental understanding of the thermal conductance of solid-liquid interfaces, and the thermal conductivity of nanofluids and nanoscale composite materials. • The thermal conductance of interfaces between carbon nanotubes and a surrounding matrix of organic molecules is exceptionally small and this small value of the interface conductance limits the enhancement in thermal conductivity that can be achieved by loading a fluid or a polymer with nanotubes. • The thermal conductance of interfaces between metal nanoparticles coated with hydrophilic surfactants and water is relatively high and surprisingly independent of the details of the chemical structure of the surfactant. • We extended our experimental methods to enable studies of planar interfaces between surfactant-coated metals and water where the chemical functionalization can be varied between strongly hydrophobic and strongly hydrophilic. The thermal conductance of hydrophobic interfaces establishes an upper-limit of 0.25 nm on the thickness of the vapor-layer that is often proposed to exist at hydrophobic interfaces. • Our high-precision measurements of fluid suspensions show that the thermal conductivity of fluids is not significantly enhanced by loading with a small volume fraction of spherical nanoparticles. These experimental results directly contradict some of the anomalous results in the recent literature and also rule-out proposed mechanisms for the enhanced thermal conductivity of nanofluids that are based on modification of the fluid thermal conductivity by the coupling of fluid motion and the Brownian motion of the nanoparticles.

Cahil, David, G.; Braun, Paul, V.

2006-05-31T23:59:59.000Z

99

Thermal conductivity of graphene nanoribbons in noble gaseous environments  

SciTech Connect

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.

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

100

Estimation of composite thermal conductivity of a heterogeneous methane hydrate sample using iTOUGH2  

E-Print Network (OSTI)

15–17, 2006 ESTIMATION OF COMPOSITE THERMAL CONDUCTIVITY OFABSTRACT We determined the composite thermal conductivity (kfrom granular ice. The composite thermal conductivity was

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

2006-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


101

List of Solar Thermal Process Heat Incentives | Open Energy Information  

Open Energy Info (EERE)

Process Heat Incentives Process Heat Incentives Jump to: navigation, search The following contains the list of 204 Solar Thermal Process Heat Incentives. CSV (rows 1 - 204) Incentive Incentive Type Place Applicable Sector Eligible Technologies Active 30% Business Tax Credit for Solar (Vermont) Corporate Tax Credit Vermont Commercial Industrial Photovoltaics Solar Space Heat Solar Thermal Electric Solar Thermal Process Heat Solar Water Heat No APS - Renewable Energy Incentive Program (Arizona) Utility Rebate Program Arizona Commercial Residential Anaerobic Digestion Biomass Daylighting Geothermal Electric Ground Source Heat Pumps Landfill Gas Other Distributed Generation Technologies Photovoltaics Small Hydroelectric Solar Pool Heating Solar Space Heat Solar Thermal Process Heat

102

Continuous Processing of High Thermal Conductivity Polyethylene Fibers and Sheets  

Energy.gov (U.S. Department of Energy (DOE))

Project to develop and validate a continuous manufacturing process for polyethylene fibers and sheets yielding a thermal conductivity value greater than 60 W/m.K.

103

Glass-like thermal conductivity in high efficiency thermoelectric materials  

Energy.gov (U.S. Department of Energy (DOE))

Discusses strategies to design thermoelectric materials with extremely low lattice thermal conductivity through modifications of the phonon band structure and phonon relaxation time.

104

Los Alamos probes mysteries of uranium dioxide's thermal conductivity  

NLE Websites -- All DOE Office Websites (Extended Search)

of nuclear materials into the hands of terrorists and other non-state actors. The depleted uranium dioxide crystals used for the thermal conductivity measurements were...

105

Unglazed transpired solar collector having a low thermal-conductance absorber  

DOE Patents (OSTI)

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.

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

1997-12-02T23:59:59.000Z

106

Unglazed transpired solar collector having a low thermal-conductance absorber  

DOE Patents (OSTI)

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.

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

1997-01-01T23:59:59.000Z

107

Regulation of thermal conductivity in hot galaxy clusters by MHD turbulence  

E-Print Network (OSTI)

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.

Steven A. Balbus; Christopher S. Reynolds

2008-06-05T23:59:59.000Z

108

Regulation of thermal conductivity in hot galaxy clusters by MHD turbulence  

E-Print Network (OSTI)

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 populat...

Balbus, Steven A

2008-01-01T23:59:59.000Z

109

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

E-Print Network (OSTI)

be modeled as particles possessing interfacial shells [8] or nanolayers composed of interfacial particles [9] in an effort to explain observed enhancements of fluid thermal conductivity. Fractal models have also been proposed to describe the effect... of nanoparticle-fluid mixture, Int. J. of Heat and Mass Trans. 48 (2005) 2926-2932. [10] B.X. Wang, L.P. Zing, X.F. Peng, A fractal model for predicting the effective thermal conductivity of liquid with suspension of nanoparticles, Int. J. of Heat and Mass...

Fortenberry, Stephen

2009-09-30T23:59:59.000Z

110

Composite material having high thermal conductivity and process for fabricating same  

DOE Patents (OSTI)

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.

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

1998-07-21T23:59:59.000Z

111

Composite material having high thermal conductivity and process for fabricating same  

DOE Patents (OSTI)

A process 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.

Colella, Nicholas J. (Livermore, CA); Davidson, Howard L. (San Carlos, CA); Kerns, John A. (Livermore, CA); Makowiecki, Daniel M. (Livermore, CA)

1998-01-01T23:59:59.000Z

112

FAST STATIC AND DYNAMIC GRID LEVEL THERMAL SIMULATION CONSIDERING TEMPERATURE DEPENDENT THERMAL CONDUCTIVITY OF SILICON  

E-Print Network (OSTI)

heat diffusion equation has been conventionally handled by grid-grids and an approximate delta function simulating a point heatgrid size of 64×64. To obtain transient thermal mask an impulse heat

Ziabari, Amirkoushyar

2012-01-01T23:59:59.000Z

113

Advanced Heat Transfer Fluids and Novel Thermal Storage Concepts...  

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

Systems Lehigh University: Novel Thermal Storage Technologies for Concentrating Solar Power Generation Terrafore: Heat Transfer and Latent Heat Storage in Inorganic Molten...

114

Heat conduction in relativistic neutral gases revisited  

E-Print Network (OSTI)

The kinetic theory of dilute gases to first order in the gradients yields linear relations between forces and fluxes. The heat flux for the relativistic gas has been shown to be related not only to the temperature gradient but also to the density gradient in the representation where number density, temperature and hydrodynamic velocity are the independent state variables. In this work we show the calculation of the corresponding transport coefficients from the full Boltzmann equation and compare the magnitude of the relativistic correction.

A. L. Garcia-Perciante; A. R. Mendez

2010-09-30T23:59:59.000Z

115

Firearm suppressor having enhanced thermal management for rapid heat dissipation  

DOE Patents (OSTI)

A suppressor is disclosed for use with a weapon having a barrel through which a bullet is fired. The suppressor has an inner portion having a bore extending coaxially therethrough. The inner portion is adapted to be secured to a distal end of the barrel. A plurality of axial flow segments project radially from the inner portion and form axial flow paths through which expanding propellant gasses discharged from the barrel flow through. The axial flow segments have radially extending wall portions that define sections which may be filled with thermally conductive material, which in one example is a thermally conductive foam. The conductive foam helps to dissipate heat deposited within the suppressor during firing of the weapon.

Moss, William C.; Anderson, Andrew T.

2014-08-19T23:59:59.000Z

116

Thermal Storage and Advanced Heat Transfer Fluids (Fact Sheet)  

SciTech Connect

Fact sheet describing NREL CSP Program capabilities in the area of thermal storage and advanced heat transfer fluids: measuring thermophysical properties, measuring fluid flow and heat transfer, and simulating flow of thermal energy and fluid.

Not Available

2010-08-01T23:59:59.000Z

117

Heat conduction: hyperbolic self-similar shock-waves in solids  

E-Print Network (OSTI)

Analytic solutions for cylindrical thermal waves in solid medium is given based on the nonlinear hyperbolic system of heat flux relaxation and energy conservation equations. The Fourier-Cattaneo phenomenological law is generalized where the relaxation time and heat propagation coefficient have a general power law temperature dependence. From such laws one cannot form a second order parabolic or telegraph-type equation. We consider the original non-linear hyperbolic system itself with the self-similar Ansatz for the temperature distribution and for the heat flux. As results continuous and shock-wave solutions are presented. For physical establishment numerous materials with various temperature dependent heat conduction coefficients are mentioned.

Imre Ferenc Barna; Robert Kersner

2012-04-19T23:59:59.000Z

118

Simultaneous measurement of the thermal conductivity and thermal diffusivity of unconsolidated materials by the transient hot wire method  

Science Journals Connector (OSTI)

This paper describes a new design for the transient hot wire method that can obtain the thermal conductivity and thermal diffusivity of unconsolidated materials. In this method the thermal conductivity is determined from the slope of the temperature rise versus time of an electrically heated wire. The temperature rise is detected as the unbalanced voltage of a precision Wheatstone bridge. This voltage is read by a microcomputer via a high?speed analog?to?digital converter. The instrument was designed so that measurements can be taken over a temperature range of 20–200?°C and a pressure range of atmospheric down to 10 mTorr. Tests using glycerin indicate an accuracy of 1% for the conductivity and 6% for the diffusivity and a precision of 0.4% for the conductivity and 4.5% for the diffusivity. Measurements have also been made on materials such as 50?? glass beads and unconsolidated spent oil shale.

Greg C. Glatzmaier; W. Fred Ramirez

1985-01-01T23:59:59.000Z

119

Heat conduction in relativistic systems: alternatives and perspectives  

E-Print Network (OSTI)

The non-equilibrium thermodynamics of relativistic systems have a rich phenomenology. The simplest phenomenon in the class of dissipative processes is that of heat. This letter presents a brief summary of the efforts made to tackle the problem of relativistic heat conduction. In particular, we focus on the multi-fluid approach to relativistic dissipation.

C. S. Lopez-Monsalvo

2010-11-30T23:59:59.000Z

120

Thermal management of batteries using a Variable-Conductance Insulation (VCI) enclosure  

SciTech Connect

Proper thermal management is important for optimum performance and durability of most electric-vehicle batteries. For high-temperature cells such as sodium/sulphur, a very efficient and responsive thermal control system is essential. Heat must be removed during exothermic periods and retained when the batteries are not in use. Current thermal management approaches rely on passive insulation enclosures with active cooling loops that penetrate the enclosure. This paper presents the design, analysis, and testing of an enclosure with variable conductance insulation (VCI). VCI uses a hydride with an integral electric resistance heater to expel and retrieve a small amount of hydrogen gas into a vacuum space. By controlling the amount of hydrogen gas, the thermal conductance can be varied by more than 100:1, enabling the cooling loop (cold plate) to be mounted on the enclosure exterior. By not penetrating the battery enclosure, the cooling system is simpler and more reliable. Also, heat can be retained more effectively when desired. For high temperatures, radiation shields within the vacuum space are required. Ceramic spacers are used to maintain separation of the steel enclosure materials against atmospheric loading. Ceramic-to-ceramic thermal contact resistance within the spacer assembly minimizes thermal conductance. Two full-scale (0.8-m {times} 0.9-m {times} 0.3-m) prototypes were designed, built, and tested under high-temperature 200{degrees}-350{degrees}C battery conditions. With an internal temperature of 330{degrees}C (and 20{degrees}C ambient), the measured total-enclosure minimum heat loss was 80 watts (excluding wire pass-through losses). The maximum heat rejection was 4100 watts. The insulation can be switched from minimum to maximum conductance (hydrogen pressure from 2.0 {times} 10{sup -3} to 8 torr) in 3 minutes. Switching from maximum to minimum conductance was longer (16 minutes), but still satisfactory because of the large thermal mass of the battery.

Burch, S.D.; Parish, R.C.; Keyser, M.A.

1995-05-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


121

Resonant bonding leads to low lattice thermal conductivity  

E-Print Network (OSTI)

Understanding the lattice dynamics and low thermal conductivities of IV–VI, V[subscript 2]–VI[subscript 3] and V materials is critical to the development of better thermoelectric and phase-change materials. Here we provide ...

Lee, Sangyeop

122

Investigation on thermal conductivity and AC impedance of graphite suspension  

E-Print Network (OSTI)

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 ...

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

2011-01-01T23:59:59.000Z

123

Determination of Thermal Contact Conductance of Metal Tabs for Battery Ultrasonic Welding Process  

SciTech Connect

A new experimental apparatus and data analysis algorithm were used to determine the thermal contact conductance between 0.2-mm-thick pure aluminum battery tabs as a function of contact pressure from 3.6 to 14.4 MPa. Specimens were sandwiched between one optically transparent and one infrared (IR) transparent glass windows, and heated up from one side by an intense short pulse of flash light. The temperature transient on the other side was measured by an IR camera. In order to determine the thermal contact conductance, two experiment configurations having different number of Al specimen layers were used. Numerical heat conduction simulations showed that the thermal contact conductance strongly depended on the ratio of the maximum temperature rise between the two configurations. Moreover, this ratio was not sensitive to the uncertainties of other thermal properties. Through the simulation results, a simple correlation between the gap conductance and the ratio was established. Therefore, once the ratio of the temperature rise between two configurations was experimentally measured, the thermal contact conductance could be readily determined from the correlation. The new method was fast and robust. Most importantly, the data analysis algorithm improved the measurement accuracy by considerably reducing the uncertainties associated with the thermophysical properties of materials and measurement system.

Chen, Jian [ORNL] [ORNL; Zhang, Wei [ORNL] [ORNL; Yu, Zhenzhen [ORNL] [ORNL; Feng, Zhili [ORNL] [ORNL

2012-01-01T23:59:59.000Z

124

Serpentine Thermal Coupling Between a Stream and a Conducting Body  

SciTech Connect

Here we document the effect of flow configuration on the heat transfer performance of a serpentine shaped stream embedded in a conducting solid. Several configurations with fixed volume of fluid are considered: U-shaped with varying spacing between the parallel portions of the U, serpentine shapes with three elbows, and conducting soil with several parallelepipedal shapes. We show that the spacing must be greater than a critical value in order for the heat transfer density of the stream-solid configuration to be the highest that it can be. Spacings larger than this critical value do not yield improvements in heat transfer density. We also show that even though the heat transfer is time dependent, the stream-solid configuration has an effective number of heat transfer units Ntu that is nearly constant in time. The larger Ntu values correspond to the configurations with greater heat transfer density.

Kobayashi, H.; Lorente, S.; Anderson, R.; Bejan, A.

2012-02-15T23:59:59.000Z

125

Flow and heat transfer in porous micro heat sink for thermal management of high power LEDs  

Science Journals Connector (OSTI)

A novel porous micro heat sink system is presented for thermal management of high power LEDs, which has high heat transport capability. The operational principle and heat transfer characteristics of porous micro heat sink are analyzed. Numerical model ... Keywords: Heat dissipation, High heat flux, High power LEDs, Porous media, Porous micro heat sink

Z. M. Wan; J. Liu; K. L. Su; X. H. Hu; S. S. M

2011-05-01T23:59:59.000Z

126

Reduction of Thermal Conductivity in Wafer-Bonded Silicon  

SciTech Connect

Blocks of silicon up to 3-mm thick have been formed by directly bonding stacks of thin wafer chips. These stacks showed significant reductions in the thermal conductivity in the bonding direction. In each sample, the wafer chips were obtained by polishing a commercial wafer to as thin as 36 {micro}m, followed by dicing. Stacks whose starting wafers were patterned with shallow dots showed greater reductions in thermal conductivity. Diluted-HF treatment of wafer chips prior to bonding led to the largest reduction of the effective thermal conductivity, by approximately a factor of 50. Theoretical modeling based on restricted conduction through the contacting dots and some conduction across the planar nanometer air gaps yielded fair agreement for samples fabricated without the HF treatment.

ZL Liau; LR Danielson; PM Fourspring; L Hu; G Chen; GW Turner

2006-11-27T23:59:59.000Z

127

Quantal Heating of Conducting Electrons with Discrete Spectrum  

SciTech Connect

Usually heating of conducting electrons by dc electric field results in an increase of electron temperature. In this paper we show that the dc heating of 2D electrons, placed in quantized magnetic fields, results in a peculiar electron distribution, which has the same broadening or an effective 'temperature' as the unbiased electron system. The quantal heating, however, violates strongly the Ohm's Law. In the conducting system with discrete electron spectrum the quantal heating results in spectacular decrease of electron resistance and transition of the electrons into a state with zero differential resistance (ZDR). Finally the heating leads to apparent dc driven metal-insulator transition, which correlates with the transition into the ZDR state. The correlation is very unexpected and is not understood.

Vitkalov, S. A. [Department of Physics, The City College of New York, New York, NY 10031 (United States); Bykov, A. A. [Institute of Semiconductor Physics, 630090 Novosibirsk (Russian Federation)

2011-12-23T23:59:59.000Z

128

Heat conductance in nonlinear lattices at small temperature gradients  

E-Print Network (OSTI)

This paper proposes a new methodological framework within which the heat conductance in 1D lattices can be studied. The total process of heat conductance is separated into two parts where the first one is the equilibrium process at equal temperatures $T$ of both ends and the second one -- non-equilibrium with the temperature $\\Delta T$ of one end and zero temperature of the other. This approach allows significant decrease of computational time at $\\Delta T \\to 0$. The threshold temperature $T_{\\rm thr}$ is found which scales $T_{\\rm thr}(N) \\sim N^{-3}$ with the lattice size $N$ and by convention separates two mechanisms of heat conductance: phonon mechanism dominates at $T T_{\\rm thr}$. Solitons and breathers are directly visualized in numerical experiments. The problem of heat conductance in non-linear lattices in the limit $\\Delta T \\to 0$ can be reduced to the heat conductance of harmonic lattice with time-dependent stochastic rigidities determined by the equilibrium process at temperature $T$. The detailed analysis is done for the $\\beta$-FPU lattice though main results are valid for one-dimensional lattices with arbitrary potentials.

T. Yu. Astakhova; V. N. Likhachev; G. A. Vinogradov

2010-06-09T23:59:59.000Z

129

An Analytical Study Of A 2-Layer Transient Thermal Conduction Problem As  

Open Energy Info (EERE)

Analytical Study Of A 2-Layer Transient Thermal Conduction Problem As Analytical Study Of A 2-Layer Transient Thermal Conduction Problem As Applied To Soil-Temperature Surveys Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Journal Article: An Analytical Study Of A 2-Layer Transient Thermal Conduction Problem As Applied To Soil-Temperature Surveys Details Activities (0) Areas (0) Regions (0) Abstract: The soil temperature survey is an inexpensive exploration method in groundwater and geothermal resource investigations. In its simplest form, temperatures measured in shallow holes are analyzed to deduce variations in material properties. 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 a solution to the

130

Temperature dependence of thermal conductivities of coupled rotator lattice and the momentum diffusion in standard map  

E-Print Network (OSTI)

In contrary to other 1D momentum-conserving lattices such as the Fermi-Pasta-Ulam $\\beta$ (FPU-$\\beta$) lattice, the 1D coupled rotator lattice is a notable exception which conserves total momentum while exhibits normal heat conduction behavior. The temperature behavior of the thermal conductivities of 1D coupled rotator lattice had been studied in previous works trying to reveal the underlying physical mechanism for normal heat conduction. However, two different temperature behaviors of thermal conductivities have been claimed for the same coupled rotator lattice. These different temperature behaviors also intrigue the debate whether there is a phase transition of thermal conductivities as the function of temperature. In this work, we will revisit the temperature dependent thermal conductivities for the 1D coupled rotator lattice. We find that the temperature dependence follows a power law behavior which is different with the previously found temperature behaviors. Our results also support the claim that there is no phase transition for 1D coupled rotator lattice. We also give some discussion about the similarity of diffusion behaviors between the 1D coupled rotator lattice and the single kicked rotator also called the Chirikov standard map.

Yunyun Li; Nianbei Li; Baowen Li

2015-01-29T23:59:59.000Z

131

Gulf Power - Solar Thermal Water Heating Program | Department of Energy  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Gulf Power - Solar Thermal Water Heating Program Gulf Power - Solar Thermal Water Heating Program Gulf Power - Solar Thermal Water Heating Program < Back Eligibility Low-Income Residential Multi-Family Residential Residential Savings Category Heating & Cooling Solar Water Heating Maximum Rebate $1,000 Program Info State Florida Program Type Utility Rebate Program Provider Energy Efficiency '''''This program reopened on October 3, 2011 for 2012 applications. Funding is limited and must be reserved through online application before the installation of qualifying solar water heating systems. See Gulf Power's [http://www.gulfpower.com/renewable/solarThermal.asp Solar Water Heating] web site for more information.''''' Gulf Power offers a Solar Thermal Water Heating rebate to customers who install water heaters. This program started after the original pilot

132

Thermal conductivity of rigid foam insulations for aerospace vehicles  

Science Journals Connector (OSTI)

The present work describes measurements of the effective thermal conductivity of NCFI 24-124 foam, a spray-on foam insulation used formerly on the Space Shuttle external fuel tank. A novel apparatus to measure the effective thermal conductivity of rigid foam at temperatures ranging from 20 K to 300 K was developed and used to study three samples of NCFI 24-124 foam insulation. In preparation for measurement, the foam samples were either treated with a uniquely designed moisture absorption apparatus or different residual gases to study their impact on the effective thermal conductivity of the foam. The resulting data are compared to other measurements and mathematical models reported in the literature.

M. Barrios; S.W. Van Sciver

2013-01-01T23:59:59.000Z

133

Structure of fast shocks in the presence of heat conduction  

SciTech Connect

There are three types of magnetohydrodynamic (MHD) shocks: the fast shock, intermediate shock, and slow shock. The structure of slow shocks and intermediate shocks in the presence of heat conduction has been studied earlier [C. L. Tsai, R. H. Tsai, B. H. Wu, and L. C. Lee, Phys. Plasmas 9, 1185 (2002); C. L. Tsai, B. H. Wu, and L. C. Lee, Phys. Plasmas 12, 82501 (2005)]. Based on one-dimensional MHD numerical simulations with a heat conduction term, the evolution and structure of fast shocks are studied. The fast shock will form a foreshock in the presence of heat conduction. The foreshock is formed due to the heat flow from downstream to upstream and located in the immediate upstream of the main shock. In the steady state, the value of diffusion velocity V{sub d} in the foreshock is found to nearly equal the upstream convection velocity in the fast shock frame. It is found that the density jump across the main shock in high Mach number case can be much larger than 4 in the early simulation time. However the density jump will gradually evolve to a value smaller than 4 at steady state. By using the modified Rankine-Hugoniot relations with heat flux, the density jump across the fast shock is examined for various upstream parameters. The results show that the calculated density jump with heat flux is very close to the simulation value and the density jump can far exceed the maximum value of 4 without heat conduction. The structure of foreshock and main shock is also studied under different plasma parameters, such as the heat conductivity K{sub 0}, the ratio of upstream plasma pressure to magnetic pressure {beta}{sub 1}, Alfven Mach number M{sub A1}, and the angle {theta}{sub 1} between shock normal and magnetic field. It is found that as the upstream shock parameters K{sub 0}, {beta}{sub 1}, and M{sub A1} increase or {theta}{sub 1} decreases, the width of foreshock L{sub d} increases. The present results can be applied to fast shocks in the solar corona, solar wind, and magnetosphere, in which the heat conduction effects are important.

Tsai, C. L.; Chen, H. H.; Wu, B. H.; Lee, L. C. [Earth Dynamic System Research Center and Department of Physics, National Cheng Kung University, Tainan, 701 Taiwan and Institute of Space Science, National Central University, Jhongli, 320 Taiwan (China); Department of Physics, National Cheng Kung University, Tainan, 701 Taiwan and Institute of Space Science, National Central University, Jhongli, 320 Taiwan (China); National Space Organization, Hsinchu, 300 Taiwan (China); Institute of Space Science, National Central University, Jhongli, 320 Taiwan (China)

2007-12-15T23:59:59.000Z

134

Thermal conductivity of highly-ordered mesoporous titania thin films from 30 to 320 K  

E-Print Network (OSTI)

Thermal resistance of grain boundaries in alumina ceramicsThermal conductivity of highly porous zirconia”. Journal of the European Ceramic

2011-01-01T23:59:59.000Z

135

Underhood Thermal Management [Heat Transfer and Fluid Mechanics] - Nuclear  

NLE Websites -- All DOE Office Websites (Extended Search)

Underhood Thermal Underhood Thermal Management Capabilities Engineering Computation and Design Engineering and Structural Mechanics Systems/Component Design, Engineering and Drafting Heat Transfer and Fluid Mechanics Overview Thermal Hydraulic Optimization of Nuclear Systems Underhood Thermal Management Combustion Simulations Advanced Model and Methodology Development Multi-physics Reactor Performance and Safety Simulations Other Capabilities Work with Argonne Contact us For Employees Site Map Help Join us on Facebook Follow us on Twitter NE on Flickr Heat Transfer and Fluid Mechanics Bookmark and Share Underhood Thermal Management Hybrid Vehicle Underhood Thermal Analysis Hybrid Vehicle Underhood Thermal Analysis. Click on image to view larger image. In addition to nuclear system applications, the section applies its

136

Thermal Energy Storage/Heat Recovery and Energy Conservation in Food Processing  

E-Print Network (OSTI)

discharges can be made more economically attrac tank holding several thousand gallons of water tive by incorporating thermal energy storage in a maintained at 128-130?F. This scald tank is con heat recovery system. Thermal energy storage can stantly... the ultimate energy end use. of wasting this hot water to the plant drain, a heat A project conducted by the Georgia Tech exchanger was installed at the Gold Kist plant to Engineering Experiment Station to demonstrate preheat scald tank makeup water...

Combes, R. S.; Boykin, W. B.

1980-01-01T23:59:59.000Z

137

Improvement of the identification of multiwall carbon nanotubes carpet thermal conductivity by pulsed photothermal method  

SciTech Connect

Thermal properties in multiwall carbon nanotubes carpets and micro-devices are investigated using a nanosecond photothermal method. Gradually, the identification model and experimental protocol are performed to increase the method accuracy for the thermal conductivity determination. In the experimental protocol, a nanosecond UV monopulse laser beam is used to heat the surface of a multilayer (600 nm of Ti/20 {mu}m of carbon nanotube carpet) sample. In the 1D identification model with two layers and a thermal contact resistance, the effect of the laser excitation temporal shape is taken into account. In this study, this first approach allows to improve the accuracy of apparent thermal conductivity measurements of multiwall carbon nanotubes carpet. The carbon nanotubes carpet apparent thermal conductivity value went from being to 180 {+-} 5 W Multiplication-Sign m{sup -1} Multiplication-Sign K{sup -1}. In the second approach, two laser beams are coupled in order to increase the interaction time duration from 27 ns to 60 ns. It becomes possible to probe different depths in the carpet. The obtained value (180 W Multiplication-Sign m{sup -1} Multiplication-Sign K{sup -1}) confirms the pulsed photothermal method consistency for porous samples. Finally, assuming that the carbon nanotubes are parallel and without any defects, the equivalent intrinsic thermal conductivity of a single carbon nanotube is estimated to be around 3600 W Multiplication-Sign m{sup -1} Multiplication-Sign K{sup -1}.

Amin-Chalhoub, E.; Wattieaux, G.; Semmar, N.; Gaillard, M.; Petit, A.; Leborgne, C. [GREMI, Universite d'Orleans, CNRS UMR 6606, 14 rue d'Issoudun, BP 6744, 45067 Orleans (France)

2012-11-01T23:59:59.000Z

138

THERMAL CONDUCTIVITY OF POWDER INSULATIONS FOR CRYOGENIC STORAGE  

E-Print Network (OSTI)

THERMAL CONDUCTIVITY OF POWDER INSULATIONS FOR CRYOGENIC STORAGE VESSELS Y. S. Choi1 '3 , M. N), powder insulation, and foam insulation, are used in the cryogenic storage vessels. Among CP823, Advances in Cjyogenie Engineering: Transactions of the Cryogenic Engineering Conference - CEC, Vol. 51, edited by J. G

Chang, Ho-Myung

139

Remarkable Reduction of Thermal Conductivity in Silicon Nanotubes  

E-Print Network (OSTI)

localization, thermoelectric material T hermoelectric (TE) materials can provide electricity when subjected materials can be characterized by the dimen- sionless thermoelectric figure of merit ZT ) S2 T/, where S to be responsible for the reduction of thermal conductivity. Our study suggests SiNT is a promising thermoelectric

Li, Baowen

140

Mode dependent lattice thermal conductivity of single layer graphene  

SciTech Connect

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.

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

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


141

Thin-film aerogel thermal conductivity measurements via 3?  

Science Journals Connector (OSTI)

The limiting constraint in a growing number of nano systems is the inability to thermally tune devices. Silica aerogel is widely accepted as the best solid thermal insulator in existence and offers a promising solution for microelectronic systems needing superior thermal isolation. In this study, thin-film silica aerogel films varying in thickness from 250 to 1280 nm were deposited on SiO2 substrates under a variety of deposition conditions. These samples were then thermally characterized using the 3? technique. Deposition processes for depositing the 3? testing mask to the sample were optimized and it was demonstrated that thin-film aerogel can maintain its structure in common fabrication processes for microelectromechanical systems. Results indicate that thin-film silica aerogel can maintain the unique, ultra-low thermal conductivity commonly observed in bulk aerogel, with a directly measured thermal conductivity as low as 0.024 W/m-K at temperature of 295 K and pressure between 0.1 and 1 Pa.

M.L. Bauer; C.M. Bauer; M.C. Fish; R.E. Matthews; G.T. Garner; A.W. Litchenberger; P.M. Norris

2011-01-01T23:59:59.000Z

142

Thermal response of a flat heat pipe sandwich structure to a localized heat flux  

E-Print Network (OSTI)

metal foam wick and distilled water as the working fluid. Heat was applied via a propane torch and radiative heat transfer. A novel method was developed to estimate experimentally, the heat flux distribution rights reserved. Keywords: Flat heat pipe; Thermal spreader; Heat transfer; Evaporator; Condenser 1

Wadley, Haydn

143

Measurement of the thermal conductance of the graphene/SiO2 interface Kin Fai Mak, Chun Hung Lui, and Tony F. Heinz  

E-Print Network (OSTI)

, 043112 (2012) Opposite ReD-dependencies of nanofluid (Al2O3) thermal conductivities between heating and cooling modes Appl. Phys. Lett. 101, 083111 (2012) Thermal transport in graphene supported on copper J of thermal transport in this material system2­4 is currently less advanced. The thermal transport properties

Heinz, Tony F.

144

The thermal conductivity of silicon nitride with molybdenum disilicide additions  

SciTech Connect

Room-temperature thermal conductivity has been measured for a series of silicon nitride (Si{sub 3}N{sub 4}) matrix composites with molybdenum disilicide (MoSi{sub 2}) additions of 2, 5 10, 25 and 50 wt. %. Included in these measurements were a pure MoSi{sub 2} sample and a Si{sub 3}N{sub 4} sample containing only sintering aids. Aluminum oxide (Al{sub 2}O{sub 3}) and yttrium oxide (Y{sub 2}O{sub 3}) were added as the sintering aids, at approximately 6 and 2 respectively. When the amount of MoSi{sub 2} was increased to greater than 10 wt. %, the amount of the sintering aids necessary to densify the composite was decreased. No sintering aids were added to the pure MoSi{sub 2} sample. Thermal conductivities of the Si{sub 3}N{sub 4} sample without MoSi{sub 2} and the pure MoSi{sub 2} sample wee 36 W/m.K and 52 W/m.K respectively, which agree very well with the literature values for similar materials. No statistically significant changes were observed in the thermal conductivity for those samples containing up to 10 wt. % MoSi{sub 2}. However, between 10 and 25 wt. % MoSi{sub 2} there was a dramatic decrease in the thermal conductivity from 37 to 20.9 W/m.K. The thermal conductivity then increased steadily with further additions of MoSi{sub 2} up to 52 W/m.K for the pure MoSi{sub 2} specimen.

Beecher, S.C.; Dinwiddie, R.B.; Abeel, A.M.; Lowden, R.A.

1993-12-31T23:59:59.000Z

145

The divergence of neighboring magnetic field lines and fast-particle diffusion in strong magnetohydrodynamic turbulence, with application to thermal conduction in galaxy clusters  

E-Print Network (OSTI)

We investigate field-line separation in strong MHD turbulence using direct numerical simulations. We find that in the static-magnetic-field approximation the thermal conductivity in galaxy clusters is reduced by a factor of about 50 relative to the Spitzer thermal conductivity of a non-magnetized plasma. This value is too small for heat conduction to balance radiative cooling in clusters.

Jason L. Maron; Benjamin D. G. Chandran; Eric G. Blackman

2003-03-11T23:59:59.000Z

146

Thermal conductivity of Permian Basin bedded salt at elevated pressure  

SciTech Connect

Measurements of thermal conductivity were made on five core samples of bedded rock salt from the Permian Basin in Texas. The sample size was 100 mm in diameter by 250 mm in length. Measurements were conducted under confining pressures ranging from 3.8 to 31.0 MPa and temperatures from room temperature to 473 K. Conductivity showed no dependence on confining pressure, but showed a monotonic, negative temperature dependence. Four of the five samples showed conductivities clustered in a range of 5.6 +- 0.5 W/m.K at room temperature, falling to 3.6 +- 0.3 W/m.K at 473 K. These values are approximately 20% below the values for pure halite, reflecting perhaps the 5 to 20% non-halite component of the samples. The fifth sample showed a conductivity vs temperature dependence much like that of halite. 19 references, 4 figures.

Durham, W.B.; Boro, C.O.; Beiriger, J.M.

1984-04-01T23:59:59.000Z

147

Esimation of field-scale thermal conductivities of unsaturatedrocks from in-situ temperature data  

SciTech Connect

A general approach is presented here which allows estimationof field-scale thermal properties of unsaturated rock using temperaturedata collected from in situ heater tests. The approach developed here isused to determine the thermal conductivities of the unsaturated host rockof the Drift Scale Test (DST) at Yucca Mountain, Nevada. The DST wasdesigned to obtain thermal, hydrological, mechanical, and chemical (THMC)data in the unsaturated fractured rock of Yucca Mountain. Sophisticatednumerical models have been developed to analyze these THMC data. However,though the objective of those models was to analyze "field-scale" (of theorder of tens-of-meters) THMC data, thermal conductivities measured from"laboratory-scale" core samples have been used as input parameters.While, in the absence of a better alternative, using laboratory-scalethermal conductivity values in field-scale models can be justified, suchapplications introduce uncertainties in the outcome of the models. Thetemperature data collected from the DST provides a unique opportunity toresolve some of these uncertainties. These temperature data can be usedto estimate the thermal conductivity of the DST host rock and, given thelarge volume of rock affected by heating at the DST, such an estimatewill be a more reliable effective thermal conductivity value for fieldscale application. In this paper, thus, temperature data from the DST areused to develop an estimate of the field-scale thermal conductivityvalues of the unsaturated host rock of the DST. An analytical solution isdeveloped for the temperature rise in the host rock of the DST; and usinga nonlinear fitting routine, a best-fit estimate of field-scale thermalconductivity for the DST host rock is obtained. Temperature data from theDST show evidence of two distinct thermal regimes: a zone below boiling(wet) and a zone above boiling (dry). Estimates of thermal conductivityfor both the wet and dry zones are obtained in this paper. Sensitivity ofthese estimates to the input heating power of the DST is alsoinvestigated in this paper. These estimated thermal conductivity valuesare compared with core measurements and those estimated fromgeostatistical simulations. Note that the approach presented here isapplicable to other host rock and heater test settings, provided suitablemodifications are made in the analytical solution to account fordifferences in test geometry.

Mukhopadhyay, Sumit; Tsang, Yvonne W.; Birkholzer, Jens T.

2006-06-26T23:59:59.000Z

148

Large Deviations in Stochastic Heat-Conduction Processes Provide a Gradient-Flow Structure for Heat Conduction  

E-Print Network (OSTI)

We consider three one-dimensional continuous-time Markov processes on a lattice, each of which models the conduction of heat: the family of Brownian Energy Processes with parameter $m$, a Generalized Brownian Energy Process, and the Kipnis-Marchioro-Presutti process. The hydrodynamic limit of each of these three processes is a parabolic equation, the linear heat equation in the case of the BEP$(m)$ and the KMP, and a nonlinear heat equation for the GBEP($a$). We prove the hydrodynamic limit rigorously for the BEP$(m)$, and give a formal derivation for the GBEP($a$). We then formally derive the pathwise large-deviation rate functional for the empirical measure of the three processes. These rate functionals imply gradient-flow structures for the limiting linear and nonlinear heat equations. We contrast these gradient-flow structures with those for processes describing the diffusion of mass, most importantly the class of Wasserstein gradient-flow systems. The linear and nonlinear heat-equation gradient-flow structures are each driven by entropy terms of the form $-\\log \\rho$; they involve dissipation or mobility terms of order $\\rho^2$ for the linear heat equation, and a nonlinear function of $\\rho$ for the nonlinear heat equation.

Mark A. Peletier; Frank Redig; Kiamars Vafayi

2014-03-19T23:59:59.000Z

149

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

SciTech Connect

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)

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

150

Nanoscale Graphene Disk: A Natural Functionally Graded Material --The Thermal Conductivity of Nanoscale Graphene Disk by Molecular Dynamics Simulation  

E-Print Network (OSTI)

In this letter, we investigate numerically (by non-equilibrium molecular dynamics) and analytically the thermal conductivity of nanoscale graphene disks (NGDs), and discussed the possibility to realize FGM with only one material, NGDs. We found that the NGD has a graded thermal conductivity and can be used as FGM in a large temperature range. Moreover, we show the dependent of NGDs' thermal conductivity on radius and temperature. Our study may inspire experimentalists to develop NGD based FGMs and help heat removal of hot spots on chips by graphene.

Yang, Nuo; Ma, Dengke; Lu, Tingyu; Li, Baowen

2014-01-01T23:59:59.000Z

151

Non-steady state heat conduction in composite walls  

E-Print Network (OSTI)

The problem of heat conduction in one-dimensional piecewise homogeneous composite materials is examined by providing an explicit solution of the one-dimensional heat equation in each domain. The location of the interfaces is known, but neither temperature nor heat flux are prescribed there. Instead, the physical assumptions of their continuity at the interfaces are the only conditions imposed. The problem of two semi-infinite domains and that of two finite-sized domains are examined in detail. We indicate also how to extend the solution method to the setting of one finite-sized domain surrounded on both sides by semi-infinite domains, and on that of three finite-sized domains.

Bernard Deconinck; Beatrice Pelloni; Natalie Sheils

2014-02-12T23:59:59.000Z

152

Combined use of adiabatic calorimetry and heat conduction calorimetry for quantifying propellant cook-off hazards  

Science Journals Connector (OSTI)

Recent work performed at DERA (now QinetiQ) has shown how accelerating rate calorimetry (ARC) can be used to obtain time to maximum rate curves using larger samples of energetic materials. The use of larger samples reduces the influence of thermal inertia, permitting experimental data to be gathered at temperatures closer to those likely to be encountered during manufacture, transportation or storage of an explosive device. However, in many cases, extrapolation of the time to maximum rate curve will still be necessary. Because of its low detection limit compared to the ARC, heat conduction calorimetry can be used to obtain data points at, or below, the region where an explosive system might exceed its temperature of no return and undergo a thermal explosion. Paired ARC and heat conduction calorimetry experiments have been conducted on some energetic material samples to explore this possibility further. Examples of where both agreement and disagreement are found between the two techniques are reported and the significance of these discussed. Ways in which combining ARC and heat conduction calorimetry experiments can enhance, complement and validate the results obtained from each technique are examined.

P.F. Bunyan; T.T. Griffiths; V.J. Norris

2003-01-01T23:59:59.000Z

153

Minnesota Power - Solar-Thermal Water Heating Rebate Program | Department  

Energy.gov (U.S. Department of Energy (DOE)) Indexed Site

Minnesota Power - Solar-Thermal Water Heating Rebate Program Minnesota Power - Solar-Thermal Water Heating Rebate Program Minnesota Power - Solar-Thermal Water Heating Rebate Program < Back Eligibility Commercial Industrial Low-Income Residential Multi-Family Residential Residential Savings Category Heating & Cooling Solar Water Heating Maximum Rebate Single-family unit: $2,000 Two- to three-family units: $4,000 Multi-family units (four or more): $10,000 Businesses: $25,000 Program Info Start Date 03/2010 Expiration Date 12/31/2013 State Minnesota Program Type Utility Rebate Program Rebate Amount 25% of costs Provider Minnesota Power Minnesota Power offers a 25% rebate for qualifying solar thermal water heating systems. The maximum award for single-family customers is $2,000 per customer; $4,000 for 2-3 family unit buildings; $10,000 for buildings

154

Ferrocyanide safety program: Heat load and thermal characteristics determination for selected tanks  

SciTech Connect

An analysis was conducted to determine the heat loads, conductivities, and heat distributions of waste tanks 241-BY-105, -106, -108, -110, -111, and 241-C-109 at the Hanford Site. The heat distribution of tank 241-BY-111 was determined to be homogeneously distributed throughout the sludge contained in the tank. All of the other tanks, with the exception of 241-C-109, showed evidence of a heat-producing layer at the bottom of the tanks. No evidence of a heat-producing layer in a position above the bottom was found. The thermal conductivities were determined to be within the ranges found by previous laboratory and computer analysis. The heat loads of the tanks were found to be below 2.81 kW (9,600 Btu/hr).

McLaren, J.M.; Cash, R.J.

1993-11-01T23:59:59.000Z

155

FDTD simulation of induction heating of conducting ceramic ware  

SciTech Connect

Induction heating for the treatment of metals has been in commercial use since the mid 1960`s. Traditional advantages of induction heating over the convection or radiation processes include speed of heating, possible energy savings, and the ability to customize the coil design to optimize the heating process. In this paper the authors used the Finite-Difference Time-Domain (FDTD) technique to simulate and analyze the induction heating process for highly conducting ceramics. In order to analyze frequency effects, simulations were performed at 300 kHz, 2 MHz, and 25 MHz. It is found that at higher frequencies coils with a pitch of 2 in. or greater became capacitive and generate a large, axial, electric-field component. This new axial electric field, in addition to the normally encountered azimuthal field, causes an improvement in the uniformity of the power deposition in the ceramic sample. If the sample occupies a large portion of the coil, uniformity may also be improved by using a variable-pitch coil, or by extending the length of the coil a few turns beyond the length of the sample. In a production-line arrangement, where multiple samples are placed inside the coil, it is shown that maximum uniformity is achieved when the samples are placed coaxially.

White, M.J.; Iskander, M.F.; Bringhurst, S. [Univ. of Utah, Salt Lake City, UT (United States). Electrical Engineering Dept.

1996-12-31T23:59:59.000Z

156

Analysis of thermal response of a food self-heating system  

Science Journals Connector (OSTI)

This paper presents a distributed model of heat transfer in a self-heating unit for group meals and its numerical simulation. A magnesium alloy and water exothermic reaction provides the necessary energy. The resulting governing equations of chemical reaction and heat conduction that depicts the heater performance were solved to develop an approximate analytical solution, to which experimental data found from literature were compared and curve fitted. Then, a model of a complete food-heating unit for group meals, which include a stack of four sets of food tray, heating tray, and heater sandwiched between them, as well as the cardboard container, was developed. The governing equations for heat conduction in the complete model were solved. The response in thermal performance of the heating system to the parameters that influence heating profiles of the heater such as decay constant and heat generation capacity were studied. The results show that the system thermal performance is most significantly affected by heat generation and a proper combination of heaters with different heat generation capacity can improve temperature uniformity between food trays. The results are useful for designing and optimizing self-heating multi-food tray units.

Son H. Ho; Muhammad M. Rahman; Aydin K. Sunol

2010-01-01T23:59:59.000Z

157

Thermal Hydraulic Optimization of Nuclear Systems [Heat Transfer and Fluid  

NLE Websites -- All DOE Office Websites (Extended Search)

Thermal Hydraulic Thermal Hydraulic Optimization of Nuclear Systems Capabilities Engineering Computation and Design Engineering and Structural Mechanics Systems/Component Design, Engineering and Drafting Heat Transfer and Fluid Mechanics Overview Thermal Hydraulic Optimization of Nuclear Systems Underhood Thermal Management Combustion Simulations Advanced Model and Methodology Development Multi-physics Reactor Performance and Safety Simulations Other Capabilities Work with Argonne Contact us For Employees Site Map Help Join us on Facebook Follow us on Twitter NE on Flickr Heat Transfer and Fluid Mechanics Bookmark and Share Thermal Hydraulic Optimization of Nuclear Systems Accelerator Driven Test Facility Target Accelerator Driven Test Facility Target. Click on image to view larger

158

Effective thermal conduction model for estimating global warming  

Science Journals Connector (OSTI)

This paper presents a simple way to approximate the dependence of the global mean air temperature at Earth’s surface on the atmospheric concentration of carbon dioxide. It treats the atmosphere as a blanket the effective thermal conductivity of which is a decreasing function of the amount of CO 2 present and does not involve the details of energy transport. The only data required are the CO 2 concentrations at the middle of the nineteenth and the end of the twentieth centuries and the shift in temperature that has occurred over that time. This elementary phenomenological energy-balance approach is well suited for undergraduate physics courses to illustrate thermal conduction and radiation by way of the very interesting and critically important example of greenhouse warming of Earth.

Anthony B. Wolbarst

1999-01-01T23:59:59.000Z

159

Nanofluid \\{PCMs\\} for thermal energy storage: Latent heat reduction mechanisms and a numerical study of effective thermal storage performance  

Science Journals Connector (OSTI)

Abstract The latent heat of fusion of paraffin-based nanofluids has been examined to investigate the use of enhanced phase change materials (PCMs) for thermal energy storage (TES) applications. The nanofluid approach has often been exploited to enhance thermal conductivity of PCMs, but the effects of particle addition on other thermal properties affecting TES are relatively ignored. An experimental study of paraffin-based nanofluids containing various particle sizes of multi-walled carbon nanotubes has been conducted to investigate the effect of nanoparticles on latent heat of fusion. Results demonstrated that the magnitude of nanofluid latent heat reduction increases for smaller diameter particles in suspension. Three possible mechanisms – interfacial liquid layering, Brownian motion, and particle clustering – were examined to explain further reduction in latent heat, through the weakening of molecular bond structures. Although additional research is required to explore detailed mechanisms, experimental evidence suggests that interfacial liquid layering and Brownian motion cannot explain the degree of latent heat reduction observed. A finite element model is also presented as a method of quantifying nanofluid PCM energy storage performance. Thermal properties based on modified effective medium theory and an empirical relation for latent heat of fusion were applied as model parameters to determine energy stored and extracted over a given period of time. The model results show that while micro-scale particle inclusions exhibit some performance enhancement, nanoparticles in \\{PCMs\\} provide no significant improvement in TES performance. With smaller particles, the enhancement in thermal conductivity is not significant enough to overcome the reduction in latent heat of fusion, and less energy is stored over the PCM charge period. Therefore, the nanofluid approach may not be justifiable for energy storage applications. However, since the model parameters are dependent on the material properties of the system observed, storage performance may vary for differing nanofluid materials.

Aitor Zabalegui; Dhananjay Lokapur; Hohyun Lee

2014-01-01T23:59:59.000Z

160

Modelling the vertical heat exchanger in thermal basin  

Science Journals Connector (OSTI)

In geographical area characterize by specific geological conformations such as the Viterbo area which comprehend active volcanic basins, it is difficult to use conventional geothermal plants. In fact the area presents at shallow depths thermal falde ... Keywords: heat, thermal aquifer, thermal energy

Maurizio Carlini; Sonia Castellucci

2007-06-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


161

Investigation of new heat exchanger design performance for solar thermal chemical heat pump.  

E-Print Network (OSTI)

?? The emergence of Thermally Driven Cooling system has received more attention recently due to its ability to utilize low grade heat from engine, incinerator… (more)

Cordova, Cordova

2013-01-01T23:59:59.000Z

162

In-Situ Preparation and thermal shock resistance of mullite-cordierite heat tube material for solar thermal power  

Science Journals Connector (OSTI)

In order to improve the thermal shock resistance of solar thermal heat transfer tube material, the mullite-cordierite composite ceramic as solar thermal heat transfer tube material were fabricated by...?-Al2O3......

Xiaohong Xu ???; Xionghua Ma; Jianfeng Wu…

2013-06-01T23:59:59.000Z

163

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

E-Print Network (OSTI)

thermal properties such as the Debye temperature and the thermal conductivity of materials. We demonstrate studied for the past few decades6 . Low thermal conductivity mate- rials constitute the basis of a new and predict the thermal conductivity of differ- ent materials8,9,11­16 . Such evaluation of the higher

Curtarolo, Stefano

164

Developing Low-Conductance Window Frames: Capabilities and Limitations of Current Window Heat Transfer Design Tools  

E-Print Network (OSTI)

across vertical fluid layers, Journal of Heat Transfer.fluid dynamics and conduction simulations of heat transferheat transfer through such window frames, we need, ideally, to simulate fluid

Gustavsen, Arild

2009-01-01T23:59:59.000Z

165

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

E-Print Network (OSTI)

1 Pump-probe measurements of the thermal conductivity tensor for materials lacking in conductivity corresponding to the scanning direction. Also, we demonstrate Nb- V as a low thermal conductivity thermal conductivity tensor and the illuminating spots have arbitrary intensity profiles

Cahill, David G.

166

Submitted to Phys. Rev. B, June 2013 Ultralow thermal conductivity of fullerene derivatives  

E-Print Network (OSTI)

conductivity in WSe2. The objective our study is to verify the exceptionally low thermal conductivities of these materials might affect their thermal conductivities. In addition to PCBM, we also investigate [6,6]-phenyl on the appearance of ultralow thermal conductivity in this class of materials. We use time-domain thermoreflectance

Cahill, David G.

167

E-Print Network 3.0 - angle-resolved thermal conductivity Sample...  

NLE Websites -- All DOE Office Websites (Extended Search)

single-walled carbon nanotube films Kei... , the expectation on single-walled carbon nanotubes (SWNTs) to possess high thermal conductivity has attracted... of the thermal...

168

Effective thermal conductivity of packed beds of spheres  

E-Print Network (OSTI)

of N are known only for certain types of regular packing, however, an empirical relation for m ) 0. 3 is given as N = 11. 6(l ? m) (22) When a load is applied to a bed of spheres, the contact area between spheres is determined using the Hertz... the authors compared their analytical solutions to has consistently dealt with beds of materials which have a very low thermal conductivity compared to that of the brass and aluminum spheres. These materials have been solid and hollow glass spheres, ceramic...

Duncan, Allen Buchanan

1987-01-01T23:59:59.000Z

169

Thermally Activated Desiccant Technology for Heat Recovery and Comfort  

SciTech Connect

Desiccant cooling is an important part of the diverse portfolio of Thermally Activated Technologies (TAT) designed for conversion of heat for the purpose of indoor air quality control. Thermally activated desiccant cooling incorporates a desiccant material that undergoes a cyclic process involving direct dehumidification of moist air and thermal regeneration. Desiccants fall into two categories: liquid and solid desiccants. Regardless of the type, solid or liquid, the governing principles of desiccant dehumidification systems are the same. In the dehumidification process, the vapor pressure of the moist air is higher than that of the desiccant, leading to transfer of moisture from the air to the desiccant material. By heating the desiccant, the vapor pressure differential is reversed in the regeneration process that drives the moisture from the desiccant. Figure 1 illustrates a rotary solid-desiccant dehumidifier. A burner or a thermally compatible source of waste heat can provide the required heat for regeneration.

Jalalzadeh, A. A.

2005-11-01T23:59:59.000Z

170

Latent Heat or Phase Change Thermal Energy Storage  

Science Journals Connector (OSTI)

It has been explained in sections 1.6 and 1.6.2 how phase change materials (PCM) have considerably higher thermal energy storage densities compared to sensible heat storage materials and are able to absorb or rel...

H. P. Garg; S. C. Mullick; A. K. Bhargava

1985-01-01T23:59:59.000Z

171

Thermal insulation by heat resistant polymers.  

E-Print Network (OSTI)

??Internal insulation in a solid rocket motor is a layer of heat-barrier material placed between the internal surface of the case and the propellant. The… (more)

Ahmed, Ashraf Fathy

2009-01-01T23:59:59.000Z

172

COLD FRONTS AND GAS SLOSHING IN GALAXY CLUSTERS WITH ANISOTROPIC THERMAL CONDUCTION  

SciTech Connect

Cold fronts in cluster cool cores should be erased on short timescales by thermal conduction, unless protected by magnetic fields that are 'draped' parallel to the front surfaces, suppressing conduction perpendicular to the sloshing fronts. We present a series of MHD simulations of cold front formation in the core of a galaxy cluster with anisotropic thermal conduction, exploring a parameter space of conduction strengths parallel and perpendicular to the field lines. Including conduction has a strong effect on the temperature distribution of the core and the appearance of the cold fronts. Though magnetic field lines are draping parallel to the front surfaces, preventing conduction directly across them, the temperature jumps across the fronts are nevertheless reduced. The geometry of the field is such that the cold gas below the front surfaces can be connected to hotter regions outside via field lines along directions perpendicular to the plane of the sloshing motions and along sections of the front that are not perfectly draped. This results in the heating of this gas below the front on a timescale of a Gyr, but the sharpness of the density and temperature jumps may nevertheless be preserved. By modifying the gas density distribution below the front, conduction may indirectly aid in suppressing Kelvin-Helmholtz instabilities. If conduction along the field lines is unsuppressed, we find that the characteristic sharp jumps seen in Chandra observations of cold front clusters do not form. Therefore, the presence of cold fronts in hot clusters is in contradiction with our simulations with full Spitzer conduction. This suggests that the presence of cold fronts in hot clusters could be used to place upper limits on conduction in the bulk of the intracluster medium. Finally, the combination of sloshing and anisotropic thermal conduction can result in a larger flux of heat to the core than either process in isolation. While still not sufficient to prevent a cooling catastrophe in the very central (r {approx} 5 kpc) regions of the cool core (where something else is required, such as active galactic nucleus feedback), it reduces significantly the mass of gas that experiences a cooling catastrophe outside those small radii.

ZuHone, J. A.; Markevitch, M. [Astrophysics Science Division, Laboratory for High Energy Astrophysics, Code 662, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)] [Astrophysics Science Division, Laboratory for High Energy Astrophysics, Code 662, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Ruszkowski, M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States)] [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Lee, D. [The Flash Center for Computational Science, The University of Chicago, 5747 S. Ellis, Chicago, IL 60637 (United States)] [The Flash Center for Computational Science, The University of Chicago, 5747 S. Ellis, Chicago, IL 60637 (United States)

2013-01-10T23:59:59.000Z

173

Thermal conductivity of the electrode gap of a thermionic converter, filled with inert gases, at low pressures  

SciTech Connect

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.

Modin, V.A.; Nikolaev, Y.V.

1985-11-01T23:59:59.000Z

174

Experimental and analytical analyses of the thermal conductivities and high-temperature characteristics of silica aerogels based on microstructures  

Science Journals Connector (OSTI)

An analytical heat transfer model based on scanning electron microscopy, Brunauer–Emmett–Teller and pycnometry measurements and a 3D random diffusion-limited cluster–cluster aggregation structure is proposed to calculate the temperature-dependent microstructural parameters and thermal conductivities of silica aerogels. This model is a pure prediction model, which does not need experimentally fitted empirical parameters and only needs four measured structural parameters as input parameters. This model can provide high-temperature microstructural and thermophysical properties as well as theoretical guidelines for material designs with optimum parameters. The results show that three stages occur during the thermal evolution processes of the aerogel structure with increasing temperature from 300 to 1500 K. The current analytical model is fully validated by experimental data. The constant structure assumptions used in previous heat transfer models are found to cause significant errors at higher temperatures as the temperature-dependent structure deformation significantly increases the aerogel thermal conductivity. The conductive and total thermal conductivities of silica aerogels after high-temperature heat treatments are much larger than those with no heat treatment.

Jun-Jie Zhao; Yuan-Yuan Duan; Xiao-Dong Wang; Bu-Xuan Wang

2013-01-01T23:59:59.000Z

175

High temperature latent heat thermal energy storage: Phase change materials, design considerations and performance enhancement techniques  

Science Journals Connector (OSTI)

Abstract A very common problem in solar power generation plants and various other industrial processes is the existing gap between the period of thermal energy availability and its period of usage. This situation creates the need for an effective method by which excess heat can be stored for later use. Latent heat thermal energy storage is one of the most efficient ways of storing thermal energy through which the disparity between energy production or availability and consumption can be corrected, thus avoiding wastage and increasing the process efficiency. This paper reviews a series of phase change materials, mainly inorganic salt compositions and metallic alloys, which could potentially be used as storage media in a high temperature (above 300 °C) latent heat storage system, seeking to serve the reader as a comprehensive thermophysical properties database to facilitate the material selection task for high temperature applications. Widespread utilization of latent heat storage systems has been held back by the poor thermal conductivity and some other inherent drawbacks of the use of PCMs; this paper reviews several heat transfer and performance enhancement techniques proposed in the literature and discusses a number of design considerations that must be taken into account aiming to provide a broad overview for the design of high temperature latent heat based thermal energy storage systems.

Bruno Cárdenas; Noel León

2013-01-01T23:59:59.000Z

176

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

E-Print Network (OSTI)

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 ...

Cheaito, Ramez

177

Thermal Conductivity of Certain Rock Types and its Relevance to the Storage of Nuclear Waste  

Science Journals Connector (OSTI)

Nine rocks selected from the surface of three plutons have been examined petrographically and their thermal conductivities measured in the temperature range of 100° to 500°C. The thermal conductivities of differe...

V. V. Mirkovich; J. A. Soles

1978-01-01T23:59:59.000Z

178

HEAT CONDUCTION OF SINGLE-WALLED CARBON NANOTUBE IN VARIOUS ENVIRONMENTS  

E-Print Network (OSTI)

HEAT CONDUCTION OF SINGLE-WALLED CARBON NANOTUBE IN VARIOUS ENVIRONMENTS Junichiro Shiomi-ku, Tokyo 113-8656, Japan ABSTRACT Some of our recent studies on the heat conduction of single-walled carbon, the heat conduction is investigated in more practical situations under the influence of inter

Maruyama, Shigeo

179

Thermal Properties of Uranium-Molybdenum Alloys: Phase Decomposition Effects of Heat Treatments  

E-Print Network (OSTI)

to generate computational estimates of the alloys specific heat and thermal conductivity. Section 2 describes the technical background in which this thesis is based, including uranium metal alloy theory and properties. Section 3 describes the experimental... the phases and distorted phases that occur during phase decomposition. The authors conducted numerous experiments involving uranium, plutonium, and neptunium, as well as alloys with other metals. In the a0 = 3.4808 ! 0.00314 xMo !" Mox ? 10 case...

Creasy, John Thomas

2012-02-14T23:59:59.000Z

180

High Temperature Variable Conductance Heat Pipes for Radioisotope Stirling Systems  

SciTech Connect

In a Stirling radioisotope system, heat must continually be removed from the GPHS modules, to maintain the GPHS modules and surrounding insulation at acceptable temperatures. Normally, the Stirling converter provides this cooling. If the Stirling engine stops in the current system, the insulation is designed to spoil, preventing damage to the GPHS, but also ending the mission. An alkali-metal Variable Conductance Heat Pipe (VCHP) is under development to allow multiple stops and restarts of the Stirling engine. The status of the ongoing effort in developing this technology is presented in this paper. An earlier, preliminary design had a radiator outside the Advanced Stirling Radioisotope Generator (ASRG) casing, used NaK as the working fluid, and had the reservoir located on the cold side adapter flange. The revised design has an internal radiator inside the casing, with the reservoir embedded inside the insulation. A large set of advantages are offered by this new design. In addition to reducing the overall size and mass of the VCHP, simplicity, compactness and easiness in assembling the VCHP with the ASRG are significantly enhanced. Also, the permanently elevated temperatures of the entire VCHP allows the change of the working fluid from a binary compound (NaK) to single compound (Na). The latter, by its properties, allows higher performance and further mass reduction of the system. Preliminary design and analysis shows an acceptable peak temperature of the ASRG case of 140 deg. C while the heat losses caused by the addition of the VCHP are 1.8 W.

Tarau, Calin; Walker, Kara L.; Anderson, William G. [Advanced Cooling Technologies, Inc. 1046 New Holland Ave. Lancaster, PA 17601 (United States)

2009-03-16T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


181

Report on workshop on thermal property measurements  

SciTech Connect

Results of thermogravimetric analysis of basalt is discussed. Heat capacity, thermal conductivity and thermal expansion are specifically addressed. (CBS)

Robertson, E.C.

1987-01-01T23:59:59.000Z

182

Improved 3-omega measurement of thermal conductivity in liquid, gases, and powders using a metal-coated optical fiber  

Science Journals Connector (OSTI)

A novel 3?thermal conductivitymeasurement technique called metal-coated 3? is introduced for use with liquids gases powders and aerogels. This technique employs a micron-scale metal-coated glass fiber as a heater/thermometer that is suspended within the sample. Metal-coated 3? exceeds alternate 3? based fluid sensing techniques in a number of key metrics enabling rapid measurements of small samples of materials with very low thermal effusivity (gases) using smaller temperature oscillations with lower parasitic conduction losses. Its advantages relative to existing fluid measurement techniques including transient hot-wire steady-state methods and solid-wire 3? are discussed. A generalized n-layer concentric cylindrical periodic heating solution that accounts for thermal boundary resistance is presented. Improved sensitivity to boundary conductance is recognized through this model. Metal-coated 3? was successfully validated through a benchmark study of gases and liquids spanning two-orders of magnitude in thermal conductivity.

Scott N. Schiffres; Jonathan A. Malen

2011-01-01T23:59:59.000Z

183

Numerical heat conduction in hydrodynamical models of colliding hypersonic flows  

E-Print Network (OSTI)

Hydrodynamical models of colliding hypersonic flows are presented which explore the dependence of the resulting dynamics and the characteristics of the derived X-ray emission on numerical conduction and viscosity. For the purpose of our investigation we present models of colliding flow with plane-parallel and cylindrical divergence. Numerical conduction causes erroneous heating of gas across the contact discontinuity which has implications for the rate at which the gas cools. We find that the dynamics of the shocked gas and the resulting X-ray emission are strongly dependent on the contrast in the density and temperature either side of the contact discontinuity, these effects being strongest where the postshock gas of one flow behaves quasi-adiabatically while the postshock gas of the other flow is strongly radiative. Introducing additional numerical viscosity into the simulations has the effect of damping the growth of instabilities, which in some cases act to increase the volume of shocked gas and can re-he...

Parkin, E R

2010-01-01T23:59:59.000Z

184

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

E-Print Network (OSTI)

of the phase change materials, because low thermal conductivity hinders the rate of energy storage and release of the new way of improving the thermal conductivity of phase change materials by seeding nano materials way to manipulate the thermal conductivity of nano composites using one dimensional nano material

Maruyama, Shigeo

185

Origin of Low Thermal Conductivity in Nuclear Fuels Quan Yin and Sergey Y. Savrasov  

E-Print Network (OSTI)

, the thermal conductivity of UO2 is very low, and the search for alternative materials continuesOrigin of Low Thermal Conductivity in Nuclear Fuels Quan Yin and Sergey Y. Savrasov Department in a very low thermal conductivity of modern nuclear fuels. Consider semiconducting UO2 which is a main

Savrasov, Sergej Y.

186

Calculations of dynamical properties of skutterudites: Thermal conductivity, thermal expansivity, and atomic mean-square displacement  

SciTech Connect

While the thermal conductivity of the filled skutterudites has been of great interest it had not been calculated within a microscopic theory. Here a central force, Guggenheim-McGlashen, model with parameters largely extracted from first-principles calculations and from spectroscopic data, specific to LaFe{sub 4} Sb{sub 12} or CoSb{sub 3} , is employed in a Green-Kubo/molecular dynamics calculation of thermal conductivity as a function of temperature. We find that the thermal conductivity of a filled solid is more than a factor of two lower than that of an unfilled solid, assuming the “framework” interatomic force parameters are the same between filled and unfilled solids, and that this decrease is almost entirely due to the cubic anharmonic interaction between filling and framework atoms. In addition, partially as a test of our models, we calculate thermal expansivity and isotropic atomic mean-square displacements using both molecular dynamics and lattice dynamics methods. These quantities are in reasonable agreement with experiment, increasing our confidence in the anharmonic parameters of our models. We also find an anomalously large filling-atom mode Gruneisen parameter that is apparently observed for a filled skutterudite and is observed in a clathrate.

Bernstein, N.; Feldman, J. L.; Singh, David J.

2010-01-01T23:59:59.000Z

187

T I ENHANCING THERMAL CONDUCTIVITY OF FLUIDS WITH NANOPARTICLES*  

Office of Scientific and Technical Information (OSTI)

JAM 1 1 1935 JAM 1 1 1935 b T I ENHANCING THERMAL CONDUCTIVITY OF FLUIDS WITH NANOPARTICLES* Stephen U. S. Choi 1 and J. A. Eastman 2 1 Energy Technology Division and ^Materials Science Division Argonne National Laboratory, Argonne, IL 60439 October 1995 The submitted manuscript has been authored by a contractor of the U.S. Government under contract No. W-31-109-ENG-38. Accordingly, the U.S. Government retains a nonexclusive, royalty-free license to publish or reproduce the published form of this contribution, or allow others to do so, for U.S. Government purposes. DISCLAIMER This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsi-

188

Thermal conductivity of diamond-loaded glues for the ATLAS particle physics detector  

E-Print Network (OSTI)

The ATLAS experiment is one of two large general-purpose particle detectors at the Large Hadron Collider (LHC) at the CERN laboratory in Geneva, Switzerland. ATLAS has been collecting data from the collisions of protons since December 2009, in order to investigate the conditions that existed during the early Universe and the origins of mass, and other topics in fundamental particle physics. The innermost layers of the ATLAS detector will be exposed to the most radiation over the first few years of operation at the LHC. In particular, the layer closest to the beam pipe, the B-layer, will degrade over time due to the added radiation. To compensate for its degradation, it will be replaced with an Insertable B-Layer (IBL) around 2016. The design of and R&D for the IBL is ongoing, as the hope is to use the most current technologies in the building of this new sub-detector layer. One topic of interest is the use of more thermally conductive glues in the construction of the IBL, in order to facilitate in the dissipation of heat from the detector. In this paper the measurement and use of highly thermally conductive glues, in particular those that are diamond-loaded, will be discussed. The modified transient plane source technique for thermal conductivity is applied in characterizing the glues across a wide temperature range.

E. A. Ouellette; A. Harris

2010-08-04T23:59:59.000Z

189

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

E-Print Network (OSTI)

MODEL FOR DETERMINING THE EFFECTIVE THERMAL CONDUCTIVITY OF PARTICLE BEDS WITH HIGH SOLID-TO-GAS- to-gas conductivity ratio (such as Be and He). The model has the capability of accounting with high solid-to-gas thermal conductivity ratios. This paper summarizes this modeling effort. Model

Abdou, Mohamed

190

Applications of heat pipes for high thermal load beam lines  

SciTech Connect

The high flux beam produced by insertion devices often requires special heat removal techniques. For the optical elements used in such high thermal load beam lines, the required precision demands a highly accurate design. Heat pipe cooling of critical elements of the X-1 beam line at the National Synchrotron Light Source is described. This method reduces vibrations caused by water cooling systems and simplifies the design. In some of these designs, deposited heat must be transferred through unbonded contact interfaces. A pinhole assembly and a beam position monitor designed for the X-1 beam line both transfer heat through such interfaces in an ultrahigh vacuum environment. The fundamental design objective is that of removing the heat with minimal interface thermal resistance. We present our test method and results for measuring the thermal resistance across metallic interfaces as a function of contact pressure. The design of some devices which utilize both heat pipes and thermal contact interfaces will also be described. 12 refs., 8 figs.

Shu, D.; Mortazavi, P.; Rarback, H.; Howells, M.R.

1985-01-01T23:59:59.000Z

191

Constructal entransy dissipation minimisation for 'volume-point' heat conduction without the premise of optimised last-order construct  

Science Journals Connector (OSTI)

In the 'volume-point' heat conduction problem with a steady heat source, entransy dissipation reflects the mean temperature difference. By taking entransy dissipation as an optimisation objective, the high effective-conduction channel distribution has been optimised based on rectangular element, without the premise of an optimised last-order construct. A more optimal construct and the limit of the equivalent thermal resistance are obtained. The conclusion shows that, in the hypothesis that the thermal current density in the high conductive link is linear, without a premise optimised last-order construct, the optimised construct with entransy dissipation minimisation objective is the same as the optimised construct with maximum temperature difference minimisation objective, and the mean temperature difference is 2/3 of the maximum temperature difference.

Shuhuan Wei; Lingen Chen; Fengrui Sun

2010-01-01T23:59:59.000Z

192

Effects of temperature and disorder on thermal boundary conductance at solidsolid interfaces: Nonequilibrium  

E-Print Network (OSTI)

with the constituent materials. The inter- face thermal resistance, often referred to as thermal boundary resistance between two different materials when a heat flux is applied. The inverse of thermal boundary resistance mismatched interfaces. Ã? 2007 Elsevier Ltd. All rights reserved. Keywords: Thermal boundary resistance

Zhigilei, Leonid V.

193

Convective heat transfer enhancement of laminar flow of latent functionally thermal fluid in a circular tube with constant heat flux: internal heat source model and its application  

Science Journals Connector (OSTI)

This paper analyzes the convective heat transfer enhancement mechanism of latent heat functionally thermal fluid. By using the proposed internal heat source model, the influence of each factor affecting the heat

Yinping Zhang; Xianxu Hu; Qing Hao; Xin Wang

2003-04-01T23:59:59.000Z

194

Thermal interface conductance across a graphene/hexagonal boron nitride heterojunction  

SciTech Connect

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.

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

195

Ballistic phonon thermal conductance in graphene nano-ribbon: First-principles calculations  

SciTech Connect

Ballistic phonon thermal conductances for graphene nanoribbons are investigated using first-principles calculations with the density functional perturbation theory and the Landauer theory. The phonon thermal conductance per unit width for GNR is larger than that for graphene and increases with decreasing ribbon width. The normalized thermal conductances with regard to a thermal quantum for GNRs are higher than those for the single-walled carbon nanotube that have circumferential lengths corresponding to the width of GNR.

Nakamura, Jun; Tomita, Hiroki [Department of Engineering Sciences, The University of Electro-Communications (UEC-Tokyo), 1-5-1 Chofugaoka, Chofu, Tokyo 182-8585 (Japan)

2013-12-04T23:59:59.000Z

196

Molten Glass for Thermal Storage: Advanced Molten Glass for Heat Transfer and Thermal Energy Storage  

SciTech Connect

HEATS Project: Halotechnics is developing a high-temperature thermal energy storage system using a new thermal-storage and heat-transfer material: earth-abundant and low-melting-point molten glass. Heat storage materials are critical to the energy storage process. In solar thermal storage systems, heat can be stored in these materials during the day and released at night—when the sun is not out—to drive a turbine and produce electricity. In nuclear storage systems, heat can be stored in these materials at night and released to produce electricity during daytime peak-demand hours. Halotechnics new thermal storage material targets a price that is potentially cheaper than the molten salt used in most commercial solar thermal storage systems today. It is also extremely stable at temperatures up to 1200°C—hundreds of degrees hotter than the highest temperature molten salt can handle. Being able to function at high temperatures will significantly increase the efficiency of turning heat into electricity. Halotechnics is developing a scalable system to pump, heat, store, and discharge the molten glass. The company is leveraging technology used in the modern glass industry, which has decades of experience handling molten glass.

None

2012-01-01T23:59:59.000Z

197

Evaluating the ignition sensitivity of thermal battery heat pellets  

SciTech Connect

Thermal batteries are activated by the ignition of heat pellets. If the heat pellets are not sensitive enough to the ignition stimulus, the thermal battery will not activate, resulting in a dud. Thus, to assure reliable thermal batteries, it is important to demonstrate that the pellets have satisfactory ignition sensitivity by testing a number of specimens. There are a number of statistical methods for evaluating the sensitivity of a device to some stimulus. Generally, these methods are applicable to the situation in which a single test is destructive to the specimen being tested, independent of the outcome of the test. In the case of thermal battery heat pellets, however, tests that result in a nonresponse do not totally degrade the specimen. This peculiarity provides opportunities to efficiently evaluate the ignition sensitivity of heat pellets. In this paper, a simple strategy for evaluating heat pellet ignition sensitivity (including experimental design and data analysis) is described. The relatively good asymptotic and small-sample efficiencies of this strategy are demonstrated.

Thomas, E.V.

1993-09-01T23:59:59.000Z

198

Summary Weusedthreemethodstomeasureboundarylayer conductance to heat transfer (gbH) and water vapor transfer  

E-Print Network (OSTI)

Summary Weusedthreemethodstomeasureboundarylayer conductance to heat transfer (gbH) and water vapor of transpiration). The boundary layer conductance to heat transfer is small enough that leaf temperature can become diffusion, the boundary layer around a leaf also provides resistance to the transfer of heat between a leaf

Martin, Timothy

199

Heat conduction in simple networks: The effect of interchain coupling Zonghua Liu1,2  

E-Print Network (OSTI)

Heat conduction in simple networks: The effect of interchain coupling Zonghua Liu1,2 and Baowen Li2; published 16 November 2007 Heat conduction in simple networks consisting of different one dimensional nonlinear chains is studied. We find that the coupling between chains has a different function in heat

Li, Baowen

200

Temperature measurements using multicolor pyrometry in thermal radiation heating environments  

SciTech Connect

Temperature measurements are important for thermal-structural experiments in the thermal radiation heating environments such as used for thermal-structural stress analyses. This paper describes the use of multicolor pyrometry for the measurements of diffuse surfaces in thermal radiation environments that eliminates the effects of background radiation reflections and unknown emissivities based on a least-squares algorithm. The near-infrared multicolor pyrometer had a spectral range of 1100–2400 nm, spectrum resolution of 6 nm, maximum sampling frequency of 2 kHz, working distance of 0.6 m to infinity, temperature range of 700–1700 K. The pyrometer wavelength response, nonlinear intensity response, and spectral response were all calibrated. The temperature of a graphite sample irradiated by quartz lamps was then measured during heating and cooling using the least-squares algorithm based on the calibrated irradiation data. The experiments show that higher temperatures and longer wavelengths are more suitable for the thermal measurements in the quartz lamp radiation heating system. This analysis provides a valuable method for temperature measurements of diffuse surfaces in thermal radiation environments.

Fu, Tairan, E-mail: trfu@mail.tsinghua.edu.cn [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China) [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China); Beijing Key Laboratory of CO2 Utilization and Reduction Technology, Beijing 100084 (China); Liu, Jiangfan; Duan, Minghao; Zong, Anzhou [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China)] [Key Laboratory for Thermal Science and Power Engineering of Ministry of Education, Department of Thermal Engineering, Tsinghua University, Beijing 100084 (China)

2014-04-15T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


201

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

E-Print Network (OSTI)

to solid materials like metals. Keywords: SWNT, Random Walk, Thermal Conductivity, Composites 1 at the interface between the matrix material and the SWNT plays a very important role on the effective thermal conductivity. This thermal resistance is known as the Kapitza resistance [8]. According to the acoustic theory

Maruyama, Shigeo

202

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

E-Print Network (OSTI)

light on the nature of thermal conduction in partially disordered nanostructured materials and can be used for estimating the thermal resistance of doped UNCD films. © 2008 American Institute of Physics, chemical inertness, record high thermal conductivity, high mobility of charge carriers, and high electron

203

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

E-Print Network (OSTI)

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

Paris-Sud XI, Université de

204

Thermal conductance of buckled carbon nanotubes Fumio Nishimura1  

E-Print Network (OSTI)

with the strain energy generated in the buckle. Despite the highly stained deformation, the thermal resistance have motivated applications of carbon nanotubes as thermal interface materials [4-8] and additives in nanocomposites [9-12], in practice, one needs to consider various thermal resistances that manifest in the actual

Maruyama, Shigeo

205

Thermal Conduction Path Analysis in 3-D ICs Boris Vaisband1  

E-Print Network (OSTI)

in the temperature and thermal resistance of up to, respectively, 20% and 28%. As confirmed by simulation, those [9], [10]. Thermal flow in materials is described by the Fourier Law, q = -k · T . (1) Thermal-D stack. through a unit of area) q [ W m2 ], the thermal conductivity, a property of the material k

Friedman, Eby G.

206

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

E-Print Network (OSTI)

represents the length of a material of thermal conduc- tivity providing an equivalent thermal resistance inorganic materials and anharmonic polymers have potentially intriguing thermal transport behavior. The low. This requirement proves challenging for low thermal conductivity materials like amorphous polymers. The effective

Braun, Paul

207

How Does Folding Modulate Thermal Conductivity of Graphene? Nuo Yang1,2  

E-Print Network (OSTI)

of thermal conductivity is due to scattering of low frequency phonons by the folds. Our results suggest dimensional materials. Keywords Folded graphene ribbon, thermal conductivity, phonon transport, scattering #12 conductivity of low-dimensional silicon and carbon materials11 and graphene ribbons12 were studied by EMD

Li, Baowen

208

Choose the best heat-recovery method for thermal oxidizers  

SciTech Connect

Thermal oxidation is current the most economically favorable add-on method of controlling hydrocarbon air emissions of moderate to low concentration (below 10,000 ppm). This concentration range covers emissions from a wide variety of chemical process industries (CPI) sources, including dryers, reactor vents, tank vents, and coaters. Thermal oxidizer systems consist of three basic sub-systems--burner, combustion chamber, and primary heat recovery. Selecting the type of primary heat recovery is probably the most important decision in the design of a thermal oxidizer, and requires consideration of a wide range of factors. The two most widely used types of primary heat recovery--recuperative and regenerative--each have distinct advantages and disadvantages. In general, recuperative oxidizers are simpler and less costly to purchase, whereas regenerative oxidizers offer substantially lower operating costs. Selecting between recuperative and regenerative heat recovery requires balancing a number of factors, such as capital and operating costs, exhaust gas composition and temperature, and secondary heat demand. This article provides guidance on when, where, and how to use each.

Klobucar, J.M.

1995-04-01T23:59:59.000Z

209

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

DOE Patents (OSTI)

Compositions, having the general formula (Ca[sub x]Mg[sub 1[minus]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 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 C to 1350 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. 7 figs.

Brown, J.; Hirschfeld, D.; Liu, D.M.; Yang, Y.; Li, T.; Swanson, R.E.; Van Aken, S.; Kim, J.M.

1992-04-07T23:59:59.000Z

210

Heat Conduction with Flux Condition on a Free Patch  

SciTech Connect

A new free boundary or free patch problem for the heat equation is presented. In the problem a nonlinear heat flux condition is prescribed on a free portion of the boundary, the patch, the position of which depends on the solution. The existence of a weak solution is established using the theory of set-valued pseudo monotone operators.

Kuttler, Kenneth L. [Department of Mathematics, Brigham Young University, Provo, UT 84602 (United States)], E-mail: klkuttler@math.byu.edu; Shillor, Meir [Department of Mathematics and Statistics, Oakland University, Rochester, MI 48309 (United States)], E-mail: shillor@oakland.edu

2004-08-15T23:59:59.000Z

211

Vanishing heat conductivity limit for the 2D Cahn-Hilliard-Boussinesq system  

Science Journals Connector (OSTI)

This article studies the vanishing heat conductivity limit for the 2D Cahn-Hilliard-boussinesq system in a bounded domain with non-...

Zaihong Jiang; Jishan Fan

2011-12-01T23:59:59.000Z

212

A Correction Scheme for Thermal Conductivity Measurement Using the Comparative Cut-bar Technique Based on a 3D Numerical Simulation  

SciTech Connect

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.

Douglas W. Marshall; Changhu Xing; Charles Folsom; Colby Jensen; Heng Ban

2014-05-01T23:59:59.000Z

213

EXPERIMENTAL MEASUREMENTS OF THE INTERFACE THERMAL CONDUCTANCE OF A LITHIUM METATITANATE PEBBLE BED  

E-Print Network (OSTI)

, CA 90095 aliabousena@engineering.ucla.edu The thermal properties of the lithium ceramics pebble beds will help to create a reliable database of the thermal properties of the lithium ceramics pebble beds. I heat is transferred from the hot lithium ceramic pebble beds to the coolant. The thermal properties

Abdou, Mohamed

214

Thermal conductivity, electrical resistivity, and permeability of saturated soils at various porosities  

E-Print Network (OSTI)

of Ottawa Sand . 4. Thermal Conductivity Data Analysis 5. Thermal Conductivity of Reference Materials 6. DC Resistivity Data with Plate Electrode System for Kaolinite at Porosity of 49% PAGE 48 52 54 66 71 AC Resistivity Data for Kaolinite... THERMAL CONDUCTIVITY, ELECTRICAL RESISTIVITY, AND PERMEABILITY OF SATURATED SOILS AT VARIOUS POROSITIES A Thesis by JAMES KEITH ENDERBY Submitted to the Graduate College of Texas ARM University in Partial fulfillment of the requirement...

Enderby, James Keith

2012-06-07T23:59:59.000Z

215

Aquifer thermal energy storage costs with a seasonal heat source.  

SciTech Connect

The cost of energy supplied by an aquifer thermal energy storage (ATES) system from a seasonal heat source was investigated. This investigation considers only the storage of energy from a seasonal heat source. Cost estimates are based upon the assumption that all of the energy is stored in the aquifer before delivery to the end user. Costs were estimated for point demand, residential development, and multidistrict city ATES systems using the computer code AQUASTOR which was developed specifically for the economic analysis of ATES systems. In this analysis the cost effect of varying a wide range of technical and economic parameters was examined. Those parameters exhibiting a substantial influence on ATES costs were: cost of purchased thermal energy; cost of capital; source temperature; system size; transmission distance; and aquifer efficiency. ATES-delivered energy costs are compared with the costs of hot water heated by using electric power or fuel-oils. ATES costs are shown as a function of purchased thermal energy. Both the potentially low delivered energy costs available from an ATES system and its strong cost dependence on the cost of purchased thermal energy are shown. Cost components for point demand and multi-district city ATES systems are shown. Capital and thermal energy costs dominate. Capital costs, as a percentage of total costs, increase for the multi-district city due to the addition of a large distribution system. The proportion of total cost attributable to thermal energy would change dramatically if the cost of purchased thermal energy were varied. It is concluded that ATES-delivered energy can be cost competitive with conventional energy sources under a number of economic and technical conditions. This investigation reports the cost of ATES under a wide range of assumptions concerning parameters important to ATES economics. (LCL)

Reilly, R.W.; Brown, D.R.; Huber, H.D.

1981-12-01T23:59:59.000Z

216

Flexibility in heat demand at the TU Delft campus smart thermal grid with phase change materials:.  

E-Print Network (OSTI)

??Plans have been made to change the current district heating grid at the TU Delft to a smart thermal grid. New heat suppliers will be… (more)

Van Vliet, E.H.A.

2013-01-01T23:59:59.000Z

217

Guaranteed Verification of Finite Element Solutions of Heat Conduction  

E-Print Network (OSTI)

. . . . . . . . . . . . . . . . . . 1 1.2 Research goals . . . . . . . . . . . . . . . . . . . . . . . . . 3 1.3 Outline of the dissertation . . . . . . . . . . . . . . . . . . 4 II A POSTERIORI ERROR ESTIMATION OF A THERMAL BATTERY PROBLEM WITH HIGH ORTHOTROPY . . . . . 5 2....1 Thermal battery problem and its finite element solution . . 5 2.2 Upper and lower bounds based on residual estimators . . . 12 III ILLUSTRATION OF THE MAIN DIFFICULTY . . . . . . . . 31 3.1 Model problem with boundary layer . . . . . . . . . . . . . 31...

Wang, Delin

2012-07-16T23:59:59.000Z

218

Thermal comfort, skin temperature distribution, and sensible heat loss distribution in the sitting posture in various asymmetric radiant fields  

Science Journals Connector (OSTI)

This study aimed at investigating the thermal comfort for the whole body as well as for certain local areas, skin temperatures, and sensible heat losses in various asymmetric radiant fields. Human subject experiments were conducted to assess the overall comfort sensation and local discomfort, and local skin temperatures were measured. Through thermal manikin experiments, we discovered a new method for the precise measurement of the local sensible heat loss in nonuniform thermal environments. The local sensible heat losses were measured by the use of a thermal manikin that had the same local skin temperatures as the human subjects. The experimental conditions consisted of the anterior–posterior, right–left, and up–down asymmetric thermal environments created by radiation panels. A total of 35 thermal environmental conditions were created ranging from 25.5 to 30.5 °C for air temperature, from 11.5 to 44.5 °C for surface temperature of radiation panels, from 40% RH to 50% RH for humidity, and less than 0.05 m/s for inlet air velocity to the climatic chamber. The local skin temperature changed depending on the environmental thermal nonuniformity, even if the mean skin temperature remained almost the same. It is essential to use the skin temperature distribution as well as mean skin temperature for expressing thermal comfort in nonuniform environments. The local sensible heat loss changed depending on the environmental thermal nonuniformity, even if the mean sensible heat loss remained almost the same. The relationship between the local skin temperature and local sensible heat loss cannot be depicted by a simple line; instead, it varies depending on the environmental thermal nonuniformity. The local heat discomfort in the head area was dependent on both the local skin temperature and local sensible heat loss. However, the local cold discomfort in the foot area was related only to the local skin temperature.

Tomonori Sakoi; Kazuyo Tsuzuki; Shinsuke Kato; Ryozo Ooka; Doosam Song; Shengwei Zhu

2007-01-01T23:59:59.000Z

219

Methods for increasing the thermal conductivity of ultra-high molecular weight polyethylene (UHMWPE)  

E-Print Network (OSTI)

A two-part study was conducted to determine methods for producing ultra-high molecular weight polyethylene with high thermal conductivity by way of polymer chain orientation. The first portion of this report surveys current ...

Miler, Josef L

2006-01-01T23:59:59.000Z

220

Potential of thermal insulation and solar thermal energy in domestic hot water and space heating and cooling sectors in Lebanon in the period 2010 - 2030.  

E-Print Network (OSTI)

??The potential of thermal insulation and solar thermal energy in domestic water heating, space heating and cooling in residential and commercial buildings Lebanon is studied… (more)

Zaatari, Z.A.R.

2012-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


221

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

SciTech Connect

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.

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

222

Thermal conductivity of the electrode gap of a therminonic converter, filled with inert gases, at low pressures  

SciTech Connect

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.

Modin, V.A.; Nikolaev, Y.V.

1986-05-01T23:59:59.000Z

223

Phonon Heat Conduction in Corrugated Silicon Nanowires Below the Casimir Limit Christophe Blanc,1  

E-Print Network (OSTI)

very low thermal conductances of highly rough silicon nanowires [7, 18], far below the amorphous limit, 2013) The thermal conductance of straight and corrugated monocrystalline silicon nanowires has been of nanostructured materials or low dimen- sional materials has attracted growing interest [1­4], es- pecially

Paris-Sud XI, Université de

224

The simple boundary element method for transient heat conduction in functionally graded materials  

E-Print Network (OSTI)

of functional material variation (quadratic, exponential and trigonometric) of thermal conductivity and specific, in an FGM, one face of a structural component is an engineering ceramic that can resist severe thermal ceramic and fracture- resisting metal can improve the properties of thermal barrier systems because

Paulino, Glaucio H.

225

Modeling properties of chromospheric evaporation driven by thermal conduction fronts from reconnection shocks  

E-Print Network (OSTI)

Magnetic reconnection in the corona results in contracting flare loops, releasing energy into plasma heating and shocks. The hydrodynamic shocks so produced drive thermal conduction fronts (TCFs) which transport energy into the chromosphere and drive upflows (evaporation) and downflows (condensation) in the cooler, denser footpoint plasma. Observations have revealed that certain properties of the transition point between evaporation and condensation (the "flow reversal point" or FRP), such as temperature and velocity-temperature derivative at the FRP, vary between different flares. These properties may provide a diagnostic tool to determine parameters of the coronal energy release mechanism and the loop atmosphere. In this study, we develop a 1-D hydrodynamical flare loop model with a simplified three-region atmosphere (chromosphere/transition region/corona), with TCFs initiated by shocks introduced in the corona. We investigate the effect of two different flare loop parameters (post-shock temperature and tra...

Brannon, Sean

2014-01-01T23:59:59.000Z

226

Thermal characterization of submicron polyacrylonitrile fibers based on optical heating and electrical thermal sensing  

SciTech Connect

In this work, the thermal diffusivity of single submicron ({approx}800 nm) polyacrylonitrile (PAN) fibers is characterized using the recently developed optical heating and electrical thermal sensing technique. In the experiment, a thin Au film (approximately in the nanometer range) is coated on the surface of nonconductive PAN fibers. A periodically modulated laser beam is used to irradiate suspended individual fibers to achieve noncontact periodical heating. The periodical temperature response of the sample is monitored by measuring the electrical resistance variation of the thin Au coating. The experimental results for three different synthesized PAN fibers with varying Au coating thickness are presented and discussed.

Hou Jinbo; Wang Xinwei; Zhang Lijun [Department of Mechanical Engineering, N104 Walter Scott Engineering Center, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0656 (United States)

2006-10-09T23:59:59.000Z

227

Computational fluid dynamics analyses of lateral heat conduction, coolant azimuthal mixing and heat transfer predictions in a BR2 fuel assembly geometry.  

SciTech Connect

To support the analyses related to the conversion of the BR2 core from highly-enriched (HEU) to low-enriched (LEU) fuel, the thermal-hydraulics codes PLTEMP and RELAP-3D are used to evaluate the safety margins during steady-state operation (PLTEMP), as well as after a loss-of-flow, loss-of-pressure, or a loss of coolant event (RELAP). In the 1-D PLTEMP and RELAP simulations, conduction in the azimuthal and axial directions is not accounted. The very good thermal conductivity of the cladding and the fuel meat and significant temperature gradients in the lateral directions (axial and azimuthal directions) could lead to a heat flux distribution that is significantly different than the power distribution. To evaluate the significance of the lateral heat conduction, 3-D computational fluid dynamics (CFD) simulations, using the CFD code STAR-CD, were performed. Safety margin calculations are typically performed for a hot stripe, i.e., an azimuthal region of the fuel plates/coolant channel containing the power peak. In a RELAP model, for example, a channel between two plates could be divided into a number of RELAP channels (stripes) in the azimuthal direction. In a PLTEMP model, the effect of azimuthal power peaking could be taken into account by using engineering factors. However, if the thermal mixing in the azimuthal direction of a coolant channel is significant, a stripping approach could be overly conservative by not taking into account this mixing. STAR-CD simulations were also performed to study the thermal mixing in the coolant. Section II of this document presents the results of the analyses of the lateral heat conduction and azimuthal thermal mixing in a coolant channel. Finally, PLTEMP and RELAP simulations rely on the use of correlations to determine heat transfer coefficients. Previous analyses showed that the Dittus-Boelter correlation gives significantly more conservative (lower) predictions than the correlations of Sieder-Tate and Petukhov. STAR-CD 3-D simulations were performed to compare heat transfer predictions from CFD and the correlations. Section III of this document presents the results of this analysis.

Tzanos, C. P.; Dionne, B. (Nuclear Engineering Division)

2011-05-23T23:59:59.000Z

228

Two-Dimensional Computational Fluid Dynamics and Conduction Simulations of Heat Transfer in Window Frames  

E-Print Network (OSTI)

1 Two-Dimensional Computational Fluid Dynamics and Conduction Simulations of Heat Transfer Arasteh and Dragan Curcija ABSTRACT Accurately analyzing heat transfer in window frame cavities radiation heat-transfer effects.) We examine three representative complex cavity cross-section profiles

229

Thermal Conductivity of Cubic and Hexagonal Mesoporous Silica Thin Films  

E-Print Network (OSTI)

wire, serving as both a thermometer and a line heat source,as both heater and thermometer, was patterned on (A) (B)Diff Amp B Diff Amp Heater/thermometer on the sample I + V -

Coquil, Thomas; Richman, Eric K.; Hutchinson, Neal J.; Tolbert, S H; Pilon, Laurent

2009-01-01T23:59:59.000Z

230

A two-fluid model for relativistic heat conduction  

SciTech Connect

Three years ago it was presented in these proceedings the relativistic dynamics of a multi-fluid system together with various applications to a set of topical problems [1]. In this talk, I will start from such dynamics and present a covariant formulation of relativistic thermodynamics which provides us with a causal constitutive equation for the propagation of heat in a relativistic setting.

López-Monsalvo, César S. [Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México (Mexico)

2014-01-14T23:59:59.000Z

231

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

E-Print Network (OSTI)

. Active control of transport coefficients. Nanocolloïds. Cooling system Introduction Nanofluids (EastmanENHANCED 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

Paris-Sud XI, Université de

232

Electrical Conductivity, Near-Infrared Absorption, and Thermal Lens Spectroscopic Studies of Percolation of Microemulsions  

E-Print Network (OSTI)

Electrical Conductivity, Near-Infrared Absorption, and Thermal Lens Spectroscopic Studies studied below and above the percolation thresholds by electrical conductivity, near-infrared absorption. In this work the structure of microemulsions was investigated by using the near-IR absorption and thermal lens

Reid, Scott A.

233

Thermal conductance of metal-diamond interfaces at high pressure Gregory T. Hohensee  

E-Print Network (OSTI)

are concerned with the exchange of thermal energy across an interface between two materials. This topic-nonmetal interface, a two-temperature model predicts a thermal resistance of Rep = 1/ gL in series with the phononThermal conductance of metal-diamond interfaces at high pressure Gregory T. Hohensee Department

Cahill, David G.

234

Generalized model of thermal boundary conductance between SWNT and surrounding supercritical Lennard-Jones fluid  

E-Print Network (OSTI)

of the promising applications is to use SWNTs as additives to enhance thermal conductivity of composite materials of the composite can be strongly influenced by thermal boundary resistance (TBR) between carbon nanotubes, it is essential to understand TBR. Thermal boundary resistance, with its importance in small scale, has been

Maruyama, Shigeo

235

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

SciTech Connect

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.

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

236

Energy Efficient Integration of Heat Pumps into Solar District Heating Systems with Seasonal Thermal Energy Storage  

Science Journals Connector (OSTI)

Abstract Solar district heating (SDH) with seasonal thermal energy storage (STES) is a technology to provide heat for space heating and domestic hot water preparation with a high fraction of renewable energy. In order to improve the efficiency of such systems heat pumps can be integrated. By preliminary studies it was discovered, that the integration of a heat pump does not always lead to improvements from an overall energy perspective, although the operation of the heat pump increases the efficiency of other components of the system e. g. the STES or the solar collectors. Thus the integration of heat pumps in SDH systems was investigated in detail. Usually, the heat pumps are integrated in such a way, that the STES is used as low temperature heat source. No other heat sources from the ambience are used and only that amount of energy consumed by the heat pump is additionally fed into the system. In the case of an electric driven heat pump, this is highly questionable concerning economic and CO2-emission aspects. Despite that fact the operation of the heat pump influences positively the performance of other components in the system e. g. the STES and makes them more efficient. If the primary energy consumption of the heat pump is lower than the energetic benefits of all other components, the integration makes sense from an energetic point of view. A detailed assessment has been carried out to evaluate the most promising system configurations for the integration of a heat pump. Based on this approach a system concept was developed in which the integration of the heat pump is energetically further improved compared to realised systems. By means of transient system simulations this concept was optimised with regard to the primary energy consumption. A parameter study of this new concept has been performed to identify the most sensitive parameters of the system. The main result and conclusion are that higher solar fractions and also higher primary energy savings can be achieved by SDH systems using heat pumps compared systems without heat pumps.

Roman Marx; Dan Bauer; Harald Drueck

2014-01-01T23:59:59.000Z

237

Efficient Heat Storage Materials: Metallic Composites Phase-Change Materials for High-Temperature Thermal Energy Storage  

SciTech Connect

HEATS Project: MIT is developing efficient heat storage materials for use in solar and nuclear power plants. Heat storage materials are critical to the energy storage process. In solar thermal storage systems, heat can be stored in these materials during the day and released at night—when the sun’s not out—to drive a turbine and produce electricity. In nuclear storage systems, heat can be stored in these materials at night and released to produce electricity during daytime peak-demand hours. MIT is designing nanostructured heat storage materials that can store a large amount of heat per unit mass and volume. To do this, MIT is using phase change materials, which absorb a large amount of latent heat to melt from solid to liquid. MIT’s heat storage materials are designed to melt at high temperatures and conduct heat well—this makes them efficient at storing and releasing heat and enhances the overall efficiency of the thermal storage and energy-generation process. MIT’s low-cost heat storage materials also have a long life cycle, which further enhances their efficiency.

None

2011-11-21T23:59:59.000Z

238

Heat conductivity in the beta-FPU lattice. Solitons and breathers as energy carriers  

E-Print Network (OSTI)

This paper consists of two parts. The first part proposes a new methodological framework within which the heat conductivity in 1D lattices can be studied. The total process of heat conductivity is decomposed into two contributions where the first one is the equilibrium process at equal temperatures T of both lattice ends and the second -- non-equilibrium process with the temperature \\Delta T of one end and zero temperature of the other. The heat conductivity in the limit \\Delta T \\to 0 is reduced to the heat conductivity of harmonic lattice. A threshold temperature T_{thr} scales T_{thr}(N) \\sim N^{-3} with the lattice size N. Some unusual properties of heat conductivity can be exhibited on nanoscales at low temperatures. The thermodynamics of the \\beta-FPU lattice can be adequately approximated by the harmonic lattice. The second part testifies in the favor of the soliton and breather contribution to the heat conductivity in contrast to [N. Li, B. Li, S. Flach, PRL 105 (2010) 054102]. In the continuum limit the \\beta-FPU lattice is reduced to the modified Korteweg - de Vries equation with soliton and breather solutions. Numerical simulations demonstrate their high stability. New method for the visualization of moving solitons and breathers is suggested. An accurate expression for the dependence of the sound velocity on temperature is also obtained. Our results support the conjecture on the solitons and breathers contribution to the heat conductivity.

T. Yu. Astakhova; V. N. Likhachev; G. A. Vinogradov

2011-03-18T23:59:59.000Z

239

Tables for solution of the heat-conduction equation with a time-dependent heating rate  

E-Print Network (OSTI)

Tables are presented for the solution of the transient onedimensional heat flow in a solid body of constant material properties with the heating rate at one boundary dependent on time. These tables allow convenient and ...

Bergles A. E.

1962-01-01T23:59:59.000Z

240

Thermal analysis of an innovative heat pump operated desalination plant  

SciTech Connect

Sea and brackish water desalination can contribute to solve the problem of fresh water shortage in many and regions of the world. Nowadays most of the installed desalination plants employ distillation processes, like Multistage Flash (MSF), Multi effect Distillation (MED) and Vapor Compression (VC). VC process is called Mechanical Vapor Compression (MVC) when it employs a mechanical compressor, while it is called Thermal Compression when it employs a steam-ejector compressor. In this paper a new distillation plant for the treatment of sea water for drinking water purposes is presented. The most innovative feature of this system is the use of a heat pump as part of the desalting unit. The use of the heat pump in the proposed system enables desalting water evaporation and steam condensation at the same temperature, unlike conventional VC desalting systems where a steam compression stage is necessary. A thermal analysis of the heat pump-operated desalination (HPD) plant and a comparison between the HPD and a conventional MVC plant is presented, in order to determine the main advantages and disadvantages of the new system.

Site, V.D. [National Research Council of Italy, Rome (Italy)

1995-12-31T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


241

Determination of thermal accommodation coefficients from heat transfer measurements between parallel plates.  

SciTech Connect

Thermal accommodation coefficients have been derived for a variety of gas-surface combinations using an experimental apparatus developed to measure the pressure dependence of the conductive heat flux between parallel plates at unequal temperature separated by a gas-filled gap. The heat flux is inferred from temperature-difference measurements across the plates in a configuration where the plate temperatures are set with two carefully controlled thermal baths. Temperature-controlled shrouds provide for environmental isolation of the opposing test plates. Since the measured temperature differences in these experiments are very small (typically 0.3 C or less over the entire pressure range), high-precision thermistors are used to acquire the requisite temperature data. High-precision components have also been utilized on the other control and measurement subsystems in this apparatus, including system pressure, gas flow rate, plate alignment, and plate positions. The apparatus also includes the capability for in situ plasma cleaning of the installed test plates. Measured heat-flux results are used in a formula based on Direct Simulation Monte Carlo (DSMC) code calculations to determine the thermal accommodation coefficients. Thermal accommodation coefficients have been determined for three different gases (argon, nitrogen, helium) in contact with various surfaces. Materials include metals and alloys such as aluminum, gold, platinum, and 304 stainless steel. A number of materials important to fabrication of Micro Electro Mechanical Systems (MEMS) devices have also been examined. For most surfaces, coefficient values are near 0.95, 0.85, and 0.45 for argon, nitrogen, and helium, respectively. Only slight differences in accommodation as a function of surface roughness have been seen. Surface contamination appears to have a more significant effect: argon plasma treatment has been observed to reduce thermal accommodation by as much as 0.10 for helium. Mixtures of argon and helium have also been examined, and the results have been compared to DSMC simulations incorporating thermal-accommodation values from single-species experiments.

Gallis, Michail A.; Castaneda, Jaime N.; Rader, Daniel John; Torczynski, John Robert; Trott, Wayne Merle

2010-10-01T23:59:59.000Z

242

Phonon-cavity-enhanced low-temperature thermal conductance of a semiconductor nanowire with narrow constrictions  

Science Journals Connector (OSTI)

We study the effect of the phonon cavity lying in a narrow constriction of a semiconductor nanowire on the ballistic phonon thermal conductance at low temperatures. At higher temperatures, the thermal conductance of the nanowire with phonon cavity is lower than that of the nanowire without phonon cavity since more discontinuous interfaces scatter phonons. On the contrary, it is found that the cavity can enhance the thermal conductance at very low temperatures despite phonons are scattered by its interfaces. The enhancement originates from the coupling between more excited cavity modes in the phonon cavity and phonon modes in the constrictions.

Wei-Qing Huang; Gui-Fang Huang; Ling-Ling Wang; Bai-Yun Huang

2007-06-27T23:59:59.000Z

243

Study on the heat conduction of phase-change material microcapsules  

Science Journals Connector (OSTI)

The 3? approach was used to measure the effective thermal conductivity of phase-change material microcapsules (PCMMs) based on urea formaldehyde ... PCMMs with different densities were measured within the phase-change

Gangtao Zhao; Xiaohui Xu; Lin Qiu; Xinghua Zheng; Dawei Tang

2013-06-01T23:59:59.000Z

244

Anomalous heat conduction in polyethylene chains: Theory and molecular dynamics simulations  

E-Print Network (OSTI)

In 1955 Fermi, Pasta, and Ulam showed that a simple model for a nonlinear one-dimensional chain of particles can be nonergodic, which implied infinite thermal conductivity. A more recent investigation of a realistic model ...

Henry, Asegun

245

Electron-Phonon Coupling and Thermal Conductance at a Metal-Semiconductor Interface: First-principles Analysis  

E-Print Network (OSTI)

The mechanism of heat transfer and the contribution of electron-phonon coupling to thermal conductance of a metal-semiconductor interface remains unclear in the present literature. We report ab initio simulations of a technologically important titanium silicide (metal) - silicon (semiconductor) interface to estimate the Schottky barrier height (SBH), and the strength of electron-phonon and phonon-phonon heat transfer across the interface. The electron and phonon dispersion relations of TiSi$_2$ with C49 structure and the TiSi$_2$-Si interface are obtained using first-principles calculations within the density functional theory (DFT) framework. These are used to estimate electron-phonon linewidths and the associated Eliashberg function that quantifies coupling. We show that the coupling strength of electrons with interfacial phonon modes is of the same order of magnitude as coupling of electrons to phonon modes in the bulk metal, and its contribution to electron-phonon interfacial conductance is comparable to ...

Sadasivam, Sridhar; Fisher, Timothy S

2015-01-01T23:59:59.000Z

246

The Added Economic and Environmental Value of Solar Thermal Systems in Microgrids with Combined Heat and Power  

E-Print Network (OSTI)

thermal absorption solar photo- storage chiller thermalbetween solar thermal collection and storage systems and CHPimpact of solar thermal and heat storage on CO 2 emissions

Marnay, Chris

2010-01-01T23:59:59.000Z

247

The Added Economic and Environmental Value of Solar Thermal Systems in Microgrids with Combined Heat and Power  

E-Print Network (OSTI)

Environmental Value of Solar Thermal Systems in MicrogridsEnvironmental Value of Solar Thermal Systems in Microgridsa) ABSTRACT The addition of solar thermal and heat storage

Marnay, Chris

2010-01-01T23:59:59.000Z

248

Microstructure and thermal conductivity of surfactant-free NiO nanostructures  

SciTech Connect

High purity, nanometer sized surfactant-free nickel oxide (NiO) particles were produced in gram scale using a solution combustion method and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), gas pycnometry and gas adsorption analysis (BET). The average particle size of the as-synthesized NiO increases significantly with the preheating temperature of the furnace, while the specific surface area decreases. A BET specific surface area of {approx}100 m{sup 2}/g was obtained for NiO nanoparticles with size as small as 3 nm synthesized at 300 Degree-Sign C. The thermal conductivity ({kappa}) of pressed pellets of the synthesized NiO nanoparticles obtained using spark plasma sintering (SPS) and uniaxial hot pressing is drastically decreased ({approx}60%) compared to that of NiO single crystal. This strong reduction in {kappa} with particle size suggests the suitability of the synthesized surfactant-free NiO nanoparticles for use as nanoinclusions when designing high performance materials for waste heat recovery. - Graphical abstract: Highly efficient phonon scattering by surfactant-free NiO nanostructures obtained by solution combustion of a mixture of nickel (II) nitrate hexahydrate (oxidizer) and urea (fuel) at various temperatures. Highlights: Black-Right-Pointing-Pointer Fast synthesis of surfactant-free NiO nanoparticles with controllable size. Black-Right-Pointing-Pointer High specific surface area for NiO nanoparticles with size range from 3 to 7 nm. Black-Right-Pointing-Pointer Strong reduction of the thermal conductivity with decreasing particle size. Black-Right-Pointing-Pointer NiO as nanoinclusions in high performance materials for energy conversion.

Sahoo, Pranati [Laboratory for Emerging Energy and Electronic Materials, Materials Science and Engineering Department, University of Michigan, Ann Arbor, MI 48109 (United States); Department of Chemistry, University of New Orleans, New Orleans, LA 70148 (United States); Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Misra, Dinesh K. [The Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Salvador, Jim [Chemical Sciences and Materials Systems Laboratory, General Motors R and D Center, Warren, MI 48090 (United States); Makongo, Julien P.A. [Laboratory for Emerging Energy and Electronic Materials, Materials Science and Engineering Department, University of Michigan, Ann Arbor, MI 48109 (United States); Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Chaubey, Girija S. [Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Takas, Nathan J. [Laboratory for Emerging Energy and Electronic Materials, Materials Science and Engineering Department, University of Michigan, Ann Arbor, MI 48109 (United States); Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Wiley, John B. [Department of Chemistry, University of New Orleans, New Orleans, LA 70148 (United States); Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States); Poudeu, Pierre F.P., E-mail: ppoudeup@umich.edu [Laboratory for Emerging Energy and Electronic Materials, Materials Science and Engineering Department, University of Michigan, Ann Arbor, MI 48109 (United States); Department of Chemistry, University of New Orleans, New Orleans, LA 70148 (United States); Advanced Materials Research Institute, University of New Orleans, New Orleans, LA 70148 (United States)

2012-06-15T23:59:59.000Z

249

THERMAL PERFORMANCE MEASUREMENTS ON ULTIMATE HEAT SINKS - COOLING PONDS  

Office of Scientific and Technical Information (OSTI)

THERMAL PERFORMANCE MEASUREMENTS THERMAL PERFORMANCE MEASUREMENTS ON ULTIMATE HEAT SINKS - COOLING PONDS R. K. Hadlock 0 . B. Abbey Battelle Pacific Northwest Laboratories Prepared for U. S. Nuclear Regulatory Commission b + NOTICE This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Nuclear Regulatory Commission, nor any of their employees, nor any of their contractors, subcontractors, or their employees, makes any warranty, express or implied, nor assumes any legal liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, pro- duct or process disclosed, nor represents that its use would not infringe privately owned rights. F Available from National Technical Information Service

250

Conduction and convection heat transfer in composite solar collector systems with porous absorber  

Science Journals Connector (OSTI)

Steady natural convection and conduction heat transfer has been studied in composite solar collector systems. The system consists of a glazing ... bounding wall isothermal at different temperatures, two horizontal

M. Mbaye; E. Bilgen

1993-01-01T23:59:59.000Z

251

E-Print Network 3.0 - axial heat conduction Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

2006 by ASME Proceedings of ASME TURBO EXPO 2007 Summary: and with lateral conduction loss) Figure 11 Heat transfer coefficient h at five axial locations on the casing plate......

252

Thermal self-oscillations in radiative heat exchange  

E-Print Network (OSTI)

We report the effect of relaxation-type self-induced temperature oscillations in the system of two parallel plates of SiO$_2$ and VO$_2$ which exchange heat by thermal radiation in vacuum. The nonlinear feedback in the self-oscillating system is provided by metal-insulator transition in VO$_2$. Using the method of fluctuational electrodynamics we show that under the action of external laser of a constant power, the temperature of VO$_2$ plate oscillates around its phase transition value.

Dyakov, Sergey; Yan, Min; Qiu, Min

2014-01-01T23:59:59.000Z

253

EVALUATION OF THERMAL CONDUCTIVITY OF INSTALLED-IN-PLACE POLYURETHANE FOAM INSULATION BY EXPERIMENT AND ANALYSIS  

SciTech Connect

In the thermal analysis of the 9977 package, it was found that calculated temperatures, determined using a typical thermal analysis code, did not match those measured in the experimental apparatus. The analysis indicated that the thermal resistance of the overpack in the experimental apparatus was less than that expected, based on manufacturer's reported value of thermal conductivity. To resolve this question, the thermal conductivity of the installed foam was evaluated from the experimental results, using a simplified analysis. This study confirmed that the thermal resistance of the experimental apparatus was lower than that which would result from the manufacturer's published values for thermal conductivity of the foam insulation. The test package was sectioned to obtain samples for measurement of material properties. In the course of the destructive examination a large uninsulated region was found at the bottom of the package, which accounted for the anomalous results. Subsequent measurement of thermal conductivity confirmed the manufacturer's published values. The study provides useful insight into the use of simplified, scoping calculations for evaluation of thermal performance of packages.

Smith, A; Bruce Hardy, B; Kurt Eberl, K; Nick Gupta, N

2007-12-05T23:59:59.000Z

254

1.12.2014bo Akademi Univ -Thermal and Flow Engineering Piispankatu 8, 20500 Turku 1/24 8. Heat pumps, heat pipes,  

E-Print Network (OSTI)

pumps, heat pipes, cold thermal energy storage Ron Zevenhoven Ã?bo Akademi University Thermal and Flow for heating is referred to as a heat pump (mostly based on a vapour-compression cycle) Heat pumps make use electricity!) for heating and air conditioning purposes Heat pumps became popular in the 1970s

Zevenhoven, Ron

255

Current methods to handle wall conduction and room internal heat transfer  

SciTech Connect

This paper reviews methods of handling wall conduction and room internal heat exchange adopted by ASHRAE (1993 Handbook of Fundamentals and later developments), CIBSE (1986 Guide and current proposals), and the CEN/TC89/WG6 proposals to calculate heating and cooling loads and related topics.

Davies, M.G.

1999-07-01T23:59:59.000Z

256

Heat conduction in anisotropic media: Nonlinear self-adjointness and conservation laws  

E-Print Network (OSTI)

Nonlinear self-adjointness of the anisotropic nonlinear heat equation is investigated. Mathematical models of heat conduction in anisotropic media with a source are considered and a class of self-adjoint models is identified. Conservation laws corresponding to the symmetries of the equations in question are computed.

Nail H. Ibragimov; Elena D. Avdonina

2012-02-23T23:59:59.000Z

257

1D-to-3D transition of phonon heat conduction in polyethylene using molecular dynamics simulations  

E-Print Network (OSTI)

The thermal conductivity of nanostructures generally decreases with decreasing size because of classical size effects. The axial thermal conductivity of polymer chain lattices, however, can exhibit the opposite trend, ...

Henry, Asegun

258

Assessing the Thermal Environmental Impacts of an Groundwater Heat Pump in Southeastern Washington State  

SciTech Connect

A thermal analysis of a large-scale (e.g., 1900 gpm), open-loop ground source heat pump (GSHP) installed on the Pacific Northwest National Laboratory (PNNL) campus in southeastern Washington State has been performed using a numerical modeling approach. Water temperature increases at the upgradient extraction wells in the system and at the downgradient Columbia River are potential concerns, especially since heat rejection to the subsurface will occur year-round. Hence, thermal impacts of the open-loop GSHP were investigated to identify operational scenarios that minimized downgradient environmental impacts at the river, and upgradient temperature drift at the production wells. Simulations examined the sensitivity of the system to variations in pumping rates and injected water temperatures, as well as to hydraulic conductivity estimates of the aquifer. Results demonstrated that both downgradient and upgradient thermal impacts were more sensitive to injection flow rates than estimates of hydraulic conductivity. Higher injection rates at lower temperatures resulted in higher temperature increases at the extraction wells but lower increases at the river. Conversely, lower pumping rates and higher injected water temperatures resulted in a smaller temperature increase at the extraction wells, but higher increases at the river. The scenario with lower pumping rates is operationally more efficient, but does increase the likelihood of a thermal plume discharging into the Columbia River. However, this impact would be mitigated by mixing within the hyporheic zone and the Columbia River. The impact under current operational conditions is negligible, but future increases in heat rejection could require a compromise between maximizing operational efficiency and minimizing temperature increases at the shoreline.

Freedman, Vicky L.; Waichler, Scott R.; Mackley, Rob D.; Horner, Jacob A.

2012-04-01T23:59:59.000Z

259

Thermal conductivity of fluids containing suspension of nanometer-sized particles  

E-Print Network (OSTI)

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 ...

Ma, Jack Jeinhao

2006-01-01T23:59:59.000Z

260

Thermal conductivity enhancement of Ag nanowires on an organic phase change material  

Science Journals Connector (OSTI)

One of the greatest challenges in the application of organic phase change materials (PCMs) is to increase their thermal conductivity while maintaining high phase change enthalpy. 1-Tetradecanol/Ag nanowires compo...

J. L. Zeng; Z. Cao; D. W. Yang; L. X. Sun…

2010-07-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


261

Enhancing thermal conductivity of fluids with graphite nanoparticles and carbon nanotube  

DOE Patents (OSTI)

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.

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

2008-03-25T23:59:59.000Z

262

Effective thermal conductivity measurements relevant to deep borehole nuclear waste disposal  

E-Print Network (OSTI)

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 ...

Shaikh, Samina

2007-01-01T23:59:59.000Z

263

Thermal Conductivity of Ordered Mesoporous Nanocrystalline Silicon Thin Films Made from Magnesium Reduction of Polymer-  

E-Print Network (OSTI)

Thermal Conductivity of Ordered Mesoporous Nanocrystalline Silicon Thin Films Made from Magnesium-assembly of mesoporous silica followed by magnesium reduction. The periodic ordering of pores in mesoporous silicon

Pilon, Laurent

264

Gallium arsenide thermal conductivity and optical phonon relaxation times from first-principles calculations  

E-Print Network (OSTI)

In this paper, thermal conductivity of crystalline GaAs is calculated using first-principles lattice dynamics. The harmonic and cubic force constants are obtained by fitting them to the force-displacement data from density ...

Luo, Tengfei

265

Lattice thermal conductivity of Bi, Sb, and Bi-Sb alloy from first principles  

E-Print Network (OSTI)

Using first principles, we calculate the lattice thermal conductivity of Bi, Sb, and Bi-Sb alloys, which are of great importance for thermoelectric and thermomagnetic cooling applications. Our calculation reveals that the ...

Lee, Sangyeop

266

Author's personal copy Pyroelectric waste heat energy harvesting using heat conduction  

E-Print Network (OSTI)

pump, cryogenic refrigeration, and air liquefaction applications [3]. Organic Rankine cycles use heat harvesting Olsen cycle a b s t r a c t Waste heat can be directly converted into electrical energy by performing the Olsen cycle on pyroelectric materials. The Olsen cycle consists of two isothermal and two

Pilon, Laurent

267

The effect of thermal contact resistance on heat management in the electronic packaging  

E-Print Network (OSTI)

The effect of thermal contact resistance on heat management in the electronic packaging M. Grujicic the role of thermal contact resistance on heat management within a simple central processing unit (CPU interface materials on the maximum temperature experienced by the CPU. Two classes of thermal interface

Grujicic, Mica

268

Viscosity and thermal conductivity effects at first-order phase transitions in heavy-ion collisions  

SciTech Connect

Effects of viscosity and thermal conductivity on the dynamics of first-order phase transitions are studied. The nuclear gas-liquid and hadron-quark transitions in heavy-ion collisions are considered. We demonstrate that at nonzero thermal conductivity, {kappa} {ne} 0, onset of spinodal instabilities occurs on an isothermal spinodal line, whereas for {kappa} = 0 instabilities take place at lower temperatures, on an adiabatic spinodal.

Voskresensky, D. N., E-mail: D.Voskresensky@gsi.de [National Research Nuclear University 'MEPhI' (Russian Federation); Skokov, V. V., E-mail: V.Skokov@gsi.de [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH (Germany)

2012-06-15T23:59:59.000Z

269

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

E-Print Network (OSTI)

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...

Ochterbeck, Jay Matthew

2012-06-07T23:59:59.000Z

270

SHORT CIRCUITS IN THERMALLY IONIZED PLASMAS: A MECHANISM FOR INTERMITTENT HEATING OF PROTOPLANETARY DISKS  

SciTech Connect

Many astrophysical systems of interest, including protoplanetary accretion disks, are made of turbulent magnetized gas with near-solar metallicity. Thermal ionization of alkali metals in such gas exceeds non-thermal ionization when temperatures climb above roughly 1000 K. As a result, the conductivity, proportional to the ionization fraction, gains a strong, positive dependence on temperature. In this paper, we demonstrate that this relation between the temperature and the conductivity triggers an exponential instability that acts similarly to an electrical short, where the increased conductivity concentrates the current and locally increases the Ohmic heating. This contrasts with the resistivity increase expected in an ideal magnetic reconnection region. The instability acts to focus narrow current sheets into even narrower sheets with far higher currents and temperatures. We lay out the basic principles of this behavior in this paper using protoplanetary disks as our example host system, motivated by observations of chondritic meteorites and their ancestors, dust grains in protoplanetary disks, that reveal the existence of strong, frequent heating events that this instability could explain.

Hubbard, Alexander; McNally, Colin P.; Mac Low, Mordecai-Mark, E-mail: ahubbard@amnh.org, E-mail: cmcnally@nbi.dk, E-mail: mordecai@amnh.org [Department of Astrophysics, American Museum of Natural History, 79th St. at Central Park West, New York, NY 10024-5192 (United States)

2012-12-10T23:59:59.000Z

271

Size-dependent interface phonon transmission and thermal conductivity of nanolaminates  

E-Print Network (OSTI)

resistance between different materials exists since the interface breaks the regular lattice structure and superlattices as the interface distance or periodic thickness reduces. The interface thermal resistance has beenSize-dependent interface phonon transmission and thermal conductivity of nanolaminates L. H. Liang

Li, Baowen

272

Measurement of Thermal Conductivity of PbTe Nanocrystal Coated Glass Fibers by the 3 Method  

E-Print Network (OSTI)

and high aspect ratio result in a significant thermal radiation effect. We simulate the experiment using such as automobile exhaust pipes, power plant steam pipes, manufacturing industry cooling pipes, and so forth. Our the radiation effect and extract the thermal conductivity at the single fiber level. Our simulation method

Ruan, Xiulin

273

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

274

Iodine doping effects on the lattice thermal conductivity of oxidized polyacetylene nanofibers  

SciTech Connect

Thermal transport in oxidized polyacetylene (PA) nanofibers with diameters in the range between 74 and 126?nm is measured with the use of a suspended micro heater device. With the error due to both radiation and contact thermal resistance corrected via a differential measurement procedure, the obtained thermal conductivity of oxidized PA nanofibers varies in the range between 0.84 and 1.24?W?m{sup ?1}?K{sup ?1} near room temperature, and decreases by 40%–70% after iodine doping. It is also found that the thermal conductivity of oxidized PA nanofibers increases with temperature between 100 and 350?K. Because of exposure to oxygen during sample preparation, the PA nanofibers are oxidized to be electrically insulating before and after iodine doping. The measurement results reveal that iodine doping can result in enhanced lattice disorder and reduced lattice thermal conductivity of PA nanofibers. If the oxidation issue can be addressed via further research to increase the electrical conductivity via doping, the observed suppressed lattice thermal conductivity in doped polymer nanofibers can be useful for the development of such conducting polymer nanostructures for thermoelectric energy conversion.

Bi, Kedong, E-mail: lishi@mail.utexas.edu, E-mail: kedongbi@seu.edu.cn [Jiangsu Key Laboratory for Design and Manufacture of Micro-Nano Biomedical Instruments, School of Mechanical Engineering, Southeast University, Nanjing 211189 (China); Department of Mechanical Engineering, University of Texas at Austin, Austin, Texas 78712 (United States); Weathers, Annie; Pettes, Michael T.; Shi, Li, E-mail: lishi@mail.utexas.edu, E-mail: kedongbi@seu.edu.cn [Department of Mechanical Engineering, University of Texas at Austin, Austin, Texas 78712 (United States); Matsushita, Satoshi; Akagi, Kazuo [Department of Polymer Chemistry, Kyoto University, Kyoto 615-8510 (Japan); Goh, Munju [Department of Polymer Chemistry, Kyoto University, Kyoto 615-8510 (Japan); Institute of Advanced Composite Materials, Korea Institute of Science and Technology (KIST), Eunha-ri san 101, Bondong-eup, Wanju-gun, Jeolabuk-do 565-905 (Korea, Republic of)

2013-11-21T23:59:59.000Z

275

Thermal properties for the thermal-hydraulics analyses of the BR2 maximum nominal heat flux.  

SciTech Connect

This memo describes the assumptions and references used in determining the thermal properties for the various materials used in the BR2 HEU (93% enriched in {sup 235}U) to LEU (19.75% enriched in {sup 235}U) conversion feasibility analysis. More specifically, this memo focuses on the materials contained within the pressure vessel (PV), i.e., the materials that are most relevant to the study of impact of the change of fuel from HEU to LEU. This section is regrouping all of the thermal property tables. Section 2 provides a summary of the thermal properties in form of tables while the following sections present the justification of these values. Section 3 presents a brief background on the approach used to evaluate the thermal properties of the dispersion fuel meat and specific heat capacity. Sections 4 to 7 discuss the material properties for the following materials: (i) aluminum, (ii) dispersion fuel meat (UAlx-Al and U-7Mo-Al), (iii) beryllium, and (iv) stainless steel. Section 8 discusses the impact of irradiation on material properties. Section 9 summarizes the material properties for typical operating temperatures. Appendix A elaborates on how to calculate dispersed phase's volume fraction. Appendix B shows the evolution of the BR2 maximum heat flux with burnup.

Dionne, B.; Kim, Y. S.; Hofman, G. L. (Nuclear Engineering Division) [Nuclear Engineering Division

2011-05-23T23:59:59.000Z

276

General formula for the thermoelectric transport phenomena based on Fermi liquid theory: Thermoelectric power, Nernst coefficient, and thermal conductivity  

Science Journals Connector (OSTI)

On the basis of linear response transport theory, the general expressions for the thermoelectric transport coefficients, such as thermoelectric power (S), Nernst coefficient (?), and thermal conductivity (?), are derived by using Fermi liquid theory. The obtained expression is exact for the most singular term in terms of 1/?k* (?k* being the quasiparticle damping rate). We utilize Ward identities for the heat velocity which is derived by the local energy conservation law. The derived expressions enable us to calculate various thermoelectric transport coefficients in a systematic way, within the framework of the conserving approximation of Baym and Kadanoff. Thus the present expressions are very useful for studying strongly correlated electrons such as high-Tc superconductors, organic metals, and heavy fermion systems, where the current vertex correction (VC) is expected to play important roles. By using the derived expression, we calculate the thermal conductivity ? in a free-dispersion model up to second order with respect to the on-site Coulomb potential U. We find that it is slightly enhanced due to the VC for the heat current, although the VC for electron current makes the conductivity (?) of this system diverge, reflecting the absence of the umklapp process.

Hiroshi Kontani

2003-01-16T23:59:59.000Z

277

On Energy and Entropy Influxes in the Green-Naghdi Type III Theory of Heat Conduction  

E-Print Network (OSTI)

The energy-influx/entropy-influx relation in the Green-Naghdi Type III theory of heat conduction is examined within a thermodynamical framework \\`a la Mueller-Liu, where that relation is not specified a priori irrespectively of the constitutive class under attention. It is shown that the classical assumption, i.e., that the entropy influx and the energy influx are proportional via the absolute temperature, holds true if heat conduction is, in a sense that is made precise, isotropic. In addition, it is proven that the standard assumption does not hold in case of transversely isotropic conduction.

Swantje Bargmann; Antonino Favata; Paolo Podio-Guidugli

2012-09-13T23:59:59.000Z

278

The Added Economic and Environmental Value of Solar Thermal Systems in Microgrids with Combined Heat and Power  

E-Print Network (OSTI)

solar thermal and heat storage on CO 2 emissions and annual energyenergy costs, heat storage does not directly support solar thermal /energy costs. This paper focuses on analysis of the optimal interaction of solar thermal

Marnay, Chris

2010-01-01T23:59:59.000Z

279

Plate Fin Heat Exchanger Model with Axial Conduction and Variable Properties  

SciTech Connect

Future superconducting radio frequency (SRF) cavities, as part of Project X at Fermilab, will be cooled to superfluid helium temperatures by a cryogenic distribution system supplying cold supercritical helium. To reduce vapor fraction during the final Joule-Thomson (J-T) expansion into the superfluid helium cooling bath, counter-flow, plate-fin heat exchangers will be utilized. Due to their compact size and ease of fabrication, plate-fin heat exchangers are an effective option. However, the design of compact and high-effectiveness cryogenic heat exchangers operating at liquid helium temperatures requires consideration of axial heat conduction along the direction of flow, in addition to variable fluid properties. Here we present a numerical model that includes the effects of axial conduction and variable properties for a plate fin heat exchanger. The model is used to guide design decisions on heat exchanger material choice and geometry. In addition, the J-T expansion process is modeled with the heat exchanger to analyze the effect of heat load and cryogenic supply parameters. A numerical model that includes the effects of axial conduction and variable properties for a plate fin heat exchanger was developed and the effect of various design parameters on overall heat exchanger size was investigated. It was found that highly conductive metals should be avoided in the design of compact JT heat exchangers. For the geometry considered, the optimal conductivity is around 3.5 W/m-K and can range from 0.3-10 W/m-K without a large loss in performance. The model was implemented with an isenthalpic expansion process. Increasing the cold side inlet temperature from 2K to 2.2 K decreased the liquid fraction from 0.856 to 0.839 which corresponds to a 0.12 g/s increase in supercritical helium supply needed to maintain liquid level in the cooling bath. Lastly, it was found that the effectiveness increased when the heat load was below the design value. Therefore, the heat exchanger should be sized on the high end of the required heat load.

Hansen, B.J.; White, M.J.; Klebaner, A.; /Fermilab

2011-06-10T23:59:59.000Z

280

PHYSICAL REVIEW B 90, 174107 (2014) High-throughput computational screening of thermal conductivity, Debye temperature, and  

E-Print Network (OSTI)

for the past few decades [6]. Low thermal conductivity materials constitute the basis of a new generation such as the Debye temperature and the thermal conductivity of materials. We demonstrate that the AGL method, which ranking of the thermal conductivity for several different classes of semiconductor materials

Curtarolo, Stefano

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


281

Thermal Conduction in Suspended Graphene Layers A. A.BALANDIN, S. GHOSH, D. L. NIKA AND E. P. POKATILOV  

E-Print Network (OSTI)

' properties. Materials with very high or very low thermal conductivities attract particular attention due and engineering research communities to the thermal conductivity of materials. This is explained by both in its atomic structure and the knowledge of thermal conductivity can shed light on many other materials

282

Suppression of thermal conductivity in InxGa12xN alloys by nanometer-scale disorder  

E-Print Network (OSTI)

power requires low lattice thermal conductivity while maintaining high mobility of the charge carriers. The binary InN and GaN materials have high ther- mal conductivity materials9­14 (the room-temperature thermalSuppression of thermal conductivity in InxGa12xN alloys by nanometer-scale disorder T. Tong,1,a) D

Wu, Junqiao

283

Analysis of the reduced thermal conductivity in InGaAs/GaAs quantum dot lasers from chirp characteristics  

E-Print Network (OSTI)

injection which we term "thermal impact" , the ther- mal conductivity of the active region is estimatedAnalysis of the reduced thermal conductivity in InGaAs/GaAs quantum dot lasers from chirp; published online 21 September 2006 The thermal conductivity of self-organized quantum dot QD active regions

Klotzkin, David

284

Conductivity heating a subterranean oil shale to create permeability and subsequently produce oil  

SciTech Connect

This patent describes an improvement in a process in which oil is produced from a subterranean oil shale deposit by extending at least one each of heat-injecting and fluid-producing wells into the deposit, establishing a heat-conductive fluid-impermeable barrier between the interior of each heat-injecting well and the adjacent deposit, and then heating the interior of each heat-injecting well at a temperature sufficient to conductively heat oil shale kerogen and cause pyrolysis products to form fractures within the oil shale deposit through which the pyrolysis products are displaced into at least one production well. The improvement is for enhancing the uniformity of the heat fronts moving through the oil shale deposit. Also described is a process for exploiting a target oil shale interval, by progressively expanding a heated treatment zone band from about a geometric center of the target oil shale interval outward, such that the formation or extension of vertical fractures from the heated treatment zone band to the periphery of the target oil shale interval is minimized.

Van Meurs, P.; DeRouffignac, E.P.; Vinegar, H.J.; Lucid, M.F.

1989-12-12T23:59:59.000Z

285

Thermal conductance of solid-liquid interfaces Scott Huxtable, Zhenbin Ge, David G. Cahill  

E-Print Network (OSTI)

thermal conductivity in nanostructured materials ­ improved thermoelectric energy conversion improved/surfactant/water PMMA/Al2O3 nanotube/alkane #12;Modulated pump-probe apparatus f=10 MHz rf lock-in #12;Solid · Cooling rate (RC time constant) gives interface conductance G = 12 MW m-2 K-1G = 12 MW m K #12;Application

Braun, Paul

286

SENSIBLE HEAT STORAGE FOR A SOLAR THERMAL POWER PLANT  

E-Print Network (OSTI)

ADVANCED THERMAL ENERGY STORAGE CONCEPT DEFINITION STUDY FORSchilling. F. E. , Thermal Energy Storage Using PrestressedNo ~cumulate thermal energy storage. Estimate ESTrof2(

Baldwin, Thomas F.

2011-01-01T23:59:59.000Z

287

Thermal storage of solar energy as sensible heat at medium temperatures  

Science Journals Connector (OSTI)

A model has been solved in order to determine the thermal losses of a storage tank, where thermal energy is stored as sensible heat of a diathermic fluid at medium temperatures. A parametric analysis has been ...

C. Bellecci; A. Bonanno; M. Camarca; M. Conti; L. La Rotonda…

288

Transient-heat-transfer and stress analysis of a thermal-storage solar cooker module  

E-Print Network (OSTI)

This paper details the analysis carried out in Solidworks to determine the best material and configuration of a thermal-storage solar cooker module.The thermal-storage solar cooker utilizes the high-latent-heat lithium ...

Zengeni, Hazel C

2014-01-01T23:59:59.000Z

289

An apparatus for the measurement of thermal conductivity of liquid neon  

E-Print Network (OSTI)

) ~ 4 Lochtermann, Cryog nics Q, 45 (1963) ~ conductivity of liquid neon. The thermal conductivity measurements will be made using the "hot plate" method used by Grenier for measurements in liquid helium. The test cell to be used is shown 1n figure... for the experiment shown in figure 1 follows the basic design used by Grenier f' or measure- 5 ments of' the thermal conductivity of liquid. helium. The hot plate, Pl, is supported within the guard ring, P , by means of a stainless steel tube. The guard ring...

Jensen, Jerald Norman

2012-06-07T23:59:59.000Z

290

Rotating Solar Jets in Simulations of Flux Emergence with Thermal Conduction  

E-Print Network (OSTI)

We study the formation of coronal jets through numerical simulation of the emergence of a twisted magnetic flux rope into a pre-existing open magnetic field. Reconnection inside the emerging flux rope in addition to that between the emerging and pre-existing fields give rise to the violent eruption studied. The simulated event closely resembles the coronal jets ubiquitously observed by Hinode/XRT and demonstrates that heated plasma is driven into the extended atmosphere above. Thermal conduction implemented in the model allows us to qualitatively compare simulated and observed emission from such events. We find that untwisting field lines after the reconnection drive spinning outflows of plasma in the jet column. The Poynting flux in the simulated jet is dominated by the untwisting motions of the magnetic fields loaded with high-density plasma. The simulated jet is comprised of spires of untwisting field that are loaded with a mixture of cold and hot plasma and exhibit rotational motion of order 20 km/s and m...

Fang, Fang; McIntosh, Scott W

2014-01-01T23:59:59.000Z

291

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

SciTech Connect

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.

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

292

Thermal Conductivity of Hexagonal Close-Packed Solid Helium Four at High Densities  

Science Journals Connector (OSTI)

Thermal conductivity measurements between 1.1° K and 7° K have been made on solid helium samples grown under constant pressures from 185 atm to 1050 atm. At high temperatures the phonon mean free path l¯ for the highest conductivity samples at six different densities is in good agreement with the expression, l¯=Aexp(?DbT), where ?D is the Debye temperature at T=0° K, A=2.5×10-8 cm, b=2.13. Several samples grown from gas repurified by an adsorption trap exhibited mean free paths in agreement with this expression over almost four orders of magnitude. Slightly impure samples showed a considerable attenuation in the peak thermal conductivity at pressures above 320 atm. There was some evidence for anisotropy of the thermal conductivity in the umklapp region and for Poiseuille flow in the low-temperature region, but both these effects were considerably smaller than reported by other investigators for specimens grown at lower pressures.

W. D. Seward, D. Lazarus, and S. C. Fain, Jr.

1969-02-05T23:59:59.000Z

293

Modeling the heating of the Green Energy Lab in Shanghai by the geothermal heat pump combined with the solar thermal energy and ground energy storage.  

E-Print Network (OSTI)

?? This work involves the study of heating systems that combine solar collectors, geothermal heat pumps and thermal energy storage in the ground. Solar collectors… (more)

Yu, Candice Yau May

2012-01-01T23:59:59.000Z

294

FAST STATIC AND DYNAMIC GRID LEVEL THERMAL SIMULATION CONSIDERING TEMPERATURE DEPENDENT THERMAL CONDUCTIVITY OF SILICON  

E-Print Network (OSTI)

is based on an equivalent circuit of thermal resistances andof convection resistance to 0.13 K/W. This is equivalent toequivalent convection coefficient. h = 1/(R × A) The convection resistance

Ziabari, Amirkoushyar

2012-01-01T23:59:59.000Z

295

SENSIBLE HEAT STORAGE FOR A SOLAR THERMAL POWER PLANT  

E-Print Network (OSTI)

the Heat-Transfer fluid Heat-Transfer Gas Helium Helium Gaswater vapor as a fluids, heat~transfer Problems associatedthermal energy by a heat-transfer fluid and used directly or

Baldwin, Thomas F.

2011-01-01T23:59:59.000Z

296

An optimal guarding scheme for thermal conductivity measurement using a guarded cut-bar technique, part 1 experimental study  

SciTech Connect

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.

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

297

Amorphization and reduction of thermal conductivity in porous silicon by irradiation with swift heavy ions  

SciTech Connect

In this article, we demonstrate that the thermal conductivity of nanostructured porous silicon is reduced by amorphization and also that this amorphous phase in porous silicon can be created by swift (high-energy) heavy ion irradiation. Porous silicon samples with 41%-75% porosity are irradiated with 110 MeV uranium ions at six different fluences. Structural characterisation by micro-Raman spectroscopy and SEM imaging show that swift heavy ion irradiation causes the creation of an amorphous phase in porous Si but without suppressing its porous structure. We demonstrate that the amorphization of porous silicon is caused by electronic-regime interactions, which is the first time such an effect is obtained in crystalline silicon with single-ion species. Furthermore, the impact on the thermal conductivity of porous silicon is studied by micro-Raman spectroscopy and scanning thermal microscopy. The creation of an amorphous phase in porous silicon leads to a reduction of its thermal conductivity, up to a factor of 3 compared to the non-irradiated sample. Therefore, this technique could be used to enhance the thermal insulation properties of porous Si. Finally, we show that this treatment can be combined with pre-oxidation at 300 Degree-Sign C, which is known to lower the thermal conductivity of porous Si, in order to obtain an even greater reduction.

Newby, Pascal J. [Institut des Nanotechnologies de Lyon, Universite de Lyon, INL-UMR5270, CNRS, INSA de Lyon, Villeurbanne 69621 (France); Institut Interdisciplinaire d'Innovation Technologique (3IT), Universite de Sherbrooke, CNRS UMI-LN2, Sherbrooke, Quebec J1K0A5 (Canada); Canut, Bruno; Bluet, Jean-Marie; Lysenko, Vladimir [Institut des Nanotechnologies de Lyon, Universite de Lyon, INL-UMR5270, CNRS, INSA de Lyon, Villeurbanne 69621 (France); Gomes, Severine [Centre de Thermique de Lyon, Universite de Lyon, CETHIL-UMR5008, CNRS, INSA de Lyon, Villeurbanne 69621 (France); Isaiev, Mykola; Burbelo, Roman [Faculty of Physics, Taras Shevchenko National University of Kyiv, 64/13, Volodymyrs'ka St., Kyiv 01601 (Ukraine); Termentzidis, Konstantinos [Laboratoire LEMTA, Universite de Lorraine-CNRS UMR 7563, 54506 Vandoeuvre-les-Nancy cedex (France); Chantrenne, Patrice [Universite de Lyon, INSA de Lyon, MATEIS-UMR CNRS 5510, Villeurbanne 69621 (France); Frechette, Luc G. [Institut Interdisciplinaire d'Innovation Technologique (3IT), Universite de Sherbrooke, CNRS UMI-LN2, Sherbrooke, Quebec J1K0A5 (Canada)

2013-07-07T23:59:59.000Z

298

Ultra-sensitive thermal conductance measurement of one-dimensional nanostructures enhanced by differential bridge  

Science Journals Connector (OSTI)

Thermal conductivity of one-dimensional nanostructures such as nanowires nanotubes and polymer chains is of significant interest for understanding nanoscale thermal transport phenomena as well as for practical applications in nanoelectronics energy conversion and thermal management. Various techniques have been developed during the past decade for measuring this fundamental quantity at the individual nanostructure level. However the sensitivity of these techniques is generally limited to 1 × 10?9 W/K which is inadequate for small diameter nanostructures that potentially possess thermal conductance ranging between 10?11 and 10?10 W/K. In this paper we demonstrate an experimental technique which is capable of measuring thermal conductance of ?10?11 W/K. The improved sensitivity is achieved by using an on-chip Wheatstone bridge circuit that overcomes several instrumentation issues. It provides a more effective method of characterizing the thermal properties of smaller and less conductive one-dimensional nanostructures. The best sensitivity experimentally achieved experienced a noise equivalent temperature below 0.5 mK and a minimum conductancemeasurement of 1 × 10?11 W/K. Measuring the temperature fluctuation of both the four-point and bridge measurements over a 4 h time period shows a reduction in measured temperature fluctuation from 100 mK to 0.6 mK. Measurement of a 15 nm Genanowire and background conductance signal with no wire present demonstrates the increased sensitivity of the bridge method over the traditional four-point I-V measurement. This ultra-sensitive measurement platform allows for thermal measurements of materials at new size scales and will improve our understanding of thermal transport in nanoscale structures.

Matthew C. Wingert; Zack C. Y. Chen; Shooshin Kwon; Jie Xiang; Renkun Chen

2012-01-01T23:59:59.000Z

299

Thermal Conductivity of LiF and NaF and the Ziman Limit  

Science Journals Connector (OSTI)

A model calculation of lattice thermal conductivity is presented and applied to measurements on LiF and NaF crystals of high purity. The treatment is in the spirit of a Callaway analysis, but at a somwhat more fundamental level: The Ziman variational principle for thermal conductivity derived from the phonon Boltzmann equation is used, with the phonon distribution function approximated by a displaced Planck part plus another term reducing the deviation from equilibrium for high-frequency phonons. An isotropic Debye approximation for the phonon spectra of LiF and NaF gives a good fit to the conductivity data, with only two semi-adjustable parameters (Grüneisen constant and a zone-edge longitudinal phonon frequency) for the anharmonic contribution. The most important feature of the calculation is the failure of the thermal conductivity to approach the Ziman limit of resistanceless phonon-phonon N processes. This is due to the important role played by high-frequency phonons in thermal conduction. Even for an infinite perfect crystal at arbitrarily low temperatures, the Ziman limit underestimates the conductivity by at least 50%. If this prediction is correct, it is not a peculiarity of LiF and NaF alone, and should be of importance for the theory of second-sound propagation in insulators.

David Benin

1972-03-15T23:59:59.000Z

300

Experiments and thermal modeling on hybrid energy supply system of gas engine heat pumps and organic Rankine cycle  

Science Journals Connector (OSTI)

Abstract This paper presents a hybrid energy supply system, which is composed of two subsystems (gas engine-driven heat pump system (GEHP) and organic Rankine cycle system (ORC)) and three major thermodynamic cycles (the vapor compression refrigeration cycle, the internal combustion gas engine cycle and ORC). In order to convert the low-grade gas engine waste heat into high-grade electricity, the ORC system is built up using R245fa, \\{R152a\\} and R123 as working fluids, and the ORC thermal model is also developed. Meanwhile, experiments of \\{GHEPs\\} in cooling mode are conducted, and several factors which influence the cooling performance are also discussed. The results indicate that the cooling capacity, gas engine energy consumption, gas engine waste heat increase with increasing of gas engine speed and decrease with decreasing of evaporator water inlet temperature. The waste heat recovered from gas engine is more than 55% of gas engine energy consumption. F6urthermore, R123 in ORC system yields the highest thermal and exergy efficiency of 11.84% and 54.24%, respectively. Although, thermal and exergy efficiency of \\{R245fa\\} is 11.42% and 52.25% lower than that of R123, its environmental performance exhibits favorable utilization for ORC using gas engine waste heat as low-grade heat source.

Huanwei Liu; Qiushu Zhou; Haibo Zhao; Peifeng Wang

2015-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


301

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

E-Print Network (OSTI)

for the continuous (a) and dispersed (b) types [16]. 2.3 Silicon Carbide as a High Conductivity Additive Solomon et al. explored the feasibility of increasing the thermal conductivity of oxide fuels by the addition of a second, higher thermal conductivity solid... methodology used to restrict the CO or SiO gases. All processing, therefore, must take place below this temperature. Because of ! "# Table 2.3. Samples used in the thermal conductivity measurements $%&'()&*! $(+!%,-.&/! 0...

Naramore, Michael J

2010-08-03T23:59:59.000Z

302

Analysis of combined cooling, heating, and power systems under a compromised electric–thermal load strategy  

Science Journals Connector (OSTI)

Abstract Following the electric load (FE) and following the thermal load (FT) strategies both have advantages and disadvantages for combined cooling, heating and power (CCHP) systems. In this paper, the performance of different strategies is evaluated under operation cost (OC), carbon dioxide emission (CDE) and exergy efficiency (EE). Analysis of different loads in one hour is conducted under the assumption that the additional electricity is not allowed to be sold back to the grid. The results show that FE produces less OC, less CDE, and FT produces higher EE when the electric load is larger. However, FE produces less OC, less CDE and higher EE when the thermal load is larger. Based on a hybrid electric–thermal load (HET) strategy, compromised electric–thermal (CET) strategies are innovatively proposed using the efficacy coefficient method. Additional, the CCHP system of a hotel in Tianjin is analyzed for all of the strategies. The results for an entire year indicate the first CET strategy is the optimal one when dealing with OC, CDE and EE. And the second CET is the optimal one when dealing with OC and EE. Moreover, the laws are strictly correct for different buildings in qualitative terms.

Gang Han; Shijun You; Tianzhen Ye; Peng Sun; Huan Zhang

2014-01-01T23:59:59.000Z

303

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

E-Print Network (OSTI)

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.

M. C. Runyan; W. C. Jones

2008-06-11T23:59:59.000Z

304

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

E-Print Network (OSTI)

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.

Runyan, M C

2008-01-01T23:59:59.000Z

305

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

SciTech Connect

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.

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

306

A robust and well shielded thermal conductivity device for low temperature measurements  

SciTech Connect

We present a compact mechanically robust thermal conductivity measurement apparatus for measurements at low temperatures (<1 K) and high magnetic fields on small high-purity single crystal samples. A high-conductivity copper box is used to enclose the sample and all the components. The box provides protection for the thermometers, heater, and most importantly the sample increasing the portability of the mount. In addition to physical protection, the copper box is also effective at shielding radio frequency electromagnetic interference and thermal radiation, which is essential for low temperature measurements. A printed circuit board in conjunction with a braided ribbon cable is used to organize the delicate wiring and provide mechanical robustness.

Toews, W. H.; Hill, R. W. [GWPI and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)] [GWPI and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

2014-04-15T23:59:59.000Z

307

A Novel Integrated Frozen Soil Thermal Energy Storage and Ground-Source Heat Pump System  

E-Print Network (OSTI)

In this paper, a novel integrated frozen soil thermal energy storage and ground-source heat pump (IFSTS&GSHP) system in which the GHE can act as both cold thermal energy storage device and heat exchanger for GSHP is first presented. The IFSTS...

Jiang, Y.; Yao, Y.; Rong, L.; Ma, Z.

2006-01-01T23:59:59.000Z

308

SENSIBLE HEAT STORAGE FOR A SOLAR THERMAL POWER PLANT  

E-Print Network (OSTI)

for concentrating solar-thermal energy use a large number ofBoth solar power plants absorb thermal energy in high-of a solar power plant that converts thermal energy into

Baldwin, Thomas F.

2011-01-01T23:59:59.000Z

309

Effective thermal conductivity of two-phase functionally graded particulate H. M. Yin, G. H. Paulino,a  

E-Print Network (OSTI)

, a continuous trade-off of fracture toughness and high thermal conductivity of metals is made with ceramic of the ceramic portions of FGMs. The effective thermal properties in the gradation direction are es- sentialEffective thermal conductivity of two-phase functionally graded particulate composites H. M. Yin, G

Paulino, Glaucio H.

310

PHYSICAL REVIEW B 83, 174205 (2011) Testing the minimum thermal conductivity model for amorphous polymers using high pressure  

E-Print Network (OSTI)

, and propagons" to classify the vibrational modes of disordered materials and their contributions to thermal predict the thermal conductivity of most amorphous materials--and many strongly disordered crystals) simulations of polystyrene (PS)7 and proteins.8,9 Pressure tuning of the thermal conductivity enables

Braun, Paul

311

Energy-Conservation Clustering Protocol based on Heat Conductivity for Wireless Sensor Networks  

E-Print Network (OSTI)

-sensors based on MEMS (Micro-Electro-Mechanical Systems) technology. A wireless sensor network is composedEnergy-Conservation Clustering Protocol based on Heat Conductivity for Wireless Sensor Networks critical issues in wireless sensor networks is energy efficiency because of the limited energy network

Landfeldt, Bjorn

312

Two-dimensional computational fluid dynamics and conduction simulations of heat transfer in window frames with internal cavities - Part 1: Cavities only  

E-Print Network (OSTI)

1980. Numerical heat transfer and fluid flow. Washington,of heat transfer by natural convection across vertical fluidFluid Dynamics and Conduction Simulations of Heat Transfer

Gustavsen, Arild; Kohler, Christian; Arasteh, Dariush; Curcija, Dragan

2003-01-01T23:59:59.000Z

313

Soliton mechanism of the uranium nitride microdynamics and heat conductivity at high temperatures  

SciTech Connect

The microdynamics of soliton waves and localized modes of nonlinear acoustic and optical oscillations in uranium nitride has been investigated. It is shown that, upon heating, the energies of solitons in the gap between the optical and acoustic phonon bands increase, while the energies of local modes decrease. The experimentally observed quasi-resonance features, which are shifted in the gap with a change in temperature, can be manifestations of the revealed soliton waves and local modes. The microdynamics of uranium nitride heat conductivity with the stochastic generation of the observed solitons and local modes at remote energy absorption have been investigated. The temperature dependence of the heat conductivity coefficient has been determined from the temperature gradient and energy flux within the standard approach (which is to be generalized).

Semenov, V. A.; Dubovsky, O. A., E-mail: dubov@ippe.ru; Orlov, A. V. [State Scientific Center of the Russian Federation Leipunsky Institute for Physics and Power Engineering (Russian Federation)

2011-12-15T23:59:59.000Z

314

Heat conduction in systems with Kolmogorov-Arnold-Moser phase space structure  

E-Print Network (OSTI)

We study heat conduction in a billiard channel formed by two sinusoidal walls and the diffusion of particles in the corresponding channel of infinite length; the latter system has an infinite horizon, i.e., a particle can travel an arbitrary distance without colliding with the rippled walls. For small ripple amplitudes, the dynamics of the heat carriers is regular and analytical results for the temperature profile and heat flux are obtained using an effective potential. The study also proposes a formula for the temperature profile that is valid for any ripple amplitude. When the dynamics is regular, ballistic conductance and ballistic diffusion are present. The Poincar\\'e plots of the associated dynamical system (the infinitely long channel) exhibit the generic transition to chaos as ripple amplitude is increased.When no Kolmogorov-Arnold-Moser (KAM) curves are present to forbid the connection of all chaotic regions, the mean square displacement grows asymptotically with time t as tln(t).

I. F. Herrera-González; H. I. Pérez-Aguilar; A. Mendoza-Suárez; E. S Tututi

2012-09-28T23:59:59.000Z

315

On the solution of the Heaviside - Klein - Gordon thermal equation for heat transport in graphene  

E-Print Network (OSTI)

We report studies of the solution of the Heaviside - Klein - Gordon thermal equation. As the result it is shown that the solution consists of two components: the fast thermal wave and slow diffusion for very large (compared to relaxation time) time period. We argue that the fast thermal wave can be recognized as the indication of the ballistic heat transport. As an example we consider the ballistic heat transport in graphene.

Magdalena Pelc

2007-11-26T23:59:59.000Z

316

Evidence for thermalization of surface-desorbed molecules at heating rates of 108  

E-Print Network (OSTI)

Evidence for thermalization of surface-desorbed molecules at heating rates of 108 K/s C. R of aniline-d7 from a single-crystal surface 0001 of sapphire Al2O3 at a heating rate on the order of 108 K.e., pulsed heating of the sapphire surface on the nanosecond time scale leads to thermal desorption and rapid

Zare, Richard N.

317

Controlling the thermal contact resistance of a carbon nanotube heat spreader  

E-Print Network (OSTI)

Controlling the thermal contact resistance of a carbon nanotube heat spreader Kamal H. Baloch,1 electron thermal microscopy shows that the thermal contact resistance of a nanotube weakly coupled to its Norvik Voskanian,2 and John Cumings2,a 1 Department of Materials Science and Engineering, Institute

Li, Teng

318

PHYSICAL REVIEW B 83, 094521 (2011) Thermal conductivity in the mixed state of a superconductor at low magnetic fields  

E-Print Network (OSTI)

15 March 2011) We evaluate accurate low-field/low-temperature asymptotics of the thermal conductivityPHYSICAL REVIEW B 83, 094521 (2011) Thermal conductivity in the mixed state of a superconductor conductivity at low fields. DOI: 10.1103/PhysRevB.83.094521 PACS number(s): 74.25.fc, 74.25.Uv I. INTRODUCTION

Alexei, Koshelev

319

Analysis and control of the thermal runaway of ceramic slab under microwave heating  

E-Print Network (OSTI)

Analysis and control of the thermal runaway of ceramic slab under microwave heating Changjun Liu of the dielectrics during microwave heating, in which there is a big jump of the steady-state temperature while the applied microwave power varies slightly. It hinders engineers in the applications of microwave heating

Sheen, Dongwoo

320

Economical Analysis of a Groundwater Source Heat Pump with Water Thermal Storage System  

E-Print Network (OSTI)

The paper is based on a chilled and heat source for the building which has a total area of 140000m2 in the suburb of Beijing. By comparing the groundwater source heat pump of water thermal storage (GHPWTS) with a conventional chilled and heat source...

Zhou, Z.; Xu, W.; Li, J.; Zhao, J.; Niu, L.

2006-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


321

MAGNET/CRYOCOOLER INTEGRATIONFOR THERMAL STABILITY IN CONDUCTION-COOLED SYSTEMS  

E-Print Network (OSTI)

MAGNET/CRYOCOOLER INTEGRATIONFOR THERMAL STABILITY IN CONDUCTION-COOLED SYSTEMS H.-M. Chang and K The stability conditions that take into accounts the size of superconducting magnets and the refrigeration the refrigeration, causing a rise in the temperature of the magnet winding and leading to burnout. It is shown

Chang, Ho-Myung

322

Porous yttria-stabilized zirconia ceramics with ultra-low thermal conductivity  

Science Journals Connector (OSTI)

Porous yttria-stabilized zirconia (ZrO2-8 mol% Y2O3, YSZ) ceramics with ultra-low thermal conductivity (as low as 0.06 W/mK) could be fabricated by tert-butyl alcohol...

LiangFa Hu; Chang-An Wang; Yong Huang

2010-06-01T23:59:59.000Z

323

Latent Heat Based High Temperature Solar Thermal Energy Storage for Power Generation  

Science Journals Connector (OSTI)

Abstract The design of a phase change material based high temperature solar thermal energy storage device is presented. Said unit will be used as an energy reserve for a 1 kWe domestic CCHP system using a Stirling engine to produce electric power. The thermal energy storage is conducted by means of the exploitation of the latent heat of fusion of the material contained inside the tank. This method was chosen because a great energy density is obtained and, at the same time, it is possible to extract the stored energy with very small variations on the temperature, which is a favorable feature for its intended purpose. The selection of the phase change material is discussed and the design of the different components of the proposed storage model is described. It is analyzed, as well, the insulating solution applied that minimizes heat losses. Finally, a comparison between experimental results of the tests performed on the first built to scale prototype and the data obtained from computer simulations is shown.

Bruno Cárdenas; Noel León

2014-01-01T23:59:59.000Z

324

Geothermal Resource-Reservoir Investigations Based On Heat Flow And Thermal  

Open Energy Info (EERE)

Resource-Reservoir Investigations Based On Heat Flow And Thermal Resource-Reservoir Investigations Based On Heat Flow And Thermal Gradient Data For The United States Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Report: Geothermal Resource-Reservoir Investigations Based On Heat Flow And Thermal Gradient Data For The United States Details Activities (2) Areas (2) Regions (0) Abstract: Several activities related to geothermal resources in the western United States are described in this report. A database of geothermal site-specific thermal gradient and heat flow results from individual exploration wells in the western US has been assembled. Extensive temperature gradient and heat flow exploration data from the active exploration of the 1970's and 1980's were collected, compiled, and synthesized, emphasizing previously unavailable company data. Examples of

325

Integration of solar thermal energy into processes with heat demand  

Science Journals Connector (OSTI)

An integration of solar thermal energy can reduce the utility cost and the environmental impact. A proper integration of solar thermal energy is required in order to achieve ... objective of this study is to maxi...

Andreja Nemet; Zdravko Kravanja…

2012-06-01T23:59:59.000Z

326

Use of Heat From, and Thermal Management of, Photovoltaics  

Science Journals Connector (OSTI)

In flat plate PV/T collectors air or water are used for heat removal. Heat removal from concentrated photovoltaic systems has been accomplished using fluids such as air and water (Royne et al. 2003; Saki et al. 1...

Brian Norton

2014-01-01T23:59:59.000Z

327

A new approach to low-conductivity, environmentally acceptable thermal insulation. Final report  

SciTech Connect

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.

Buckley, B.; Day, J.; Ferrero-Heredia, M.; Shanklin, E.; Varadarajan, G.; Woodruff, L.

1996-02-01T23:59:59.000Z

328

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

SciTech Connect

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.

Henager, Charles H.; Nguyen, Ba Nghiep

2013-04-19T23:59:59.000Z

329

Effects of finite heat conductivity on instabilities in a rotating plasma  

SciTech Connect

Analytical theory of magnetorotational and convective instabilities in a rotating cylindrical plasma with finite heat conductivity is developed and discussed. The heat conductivity is incorporated into the standardized equations of the regular magnetohydrodynamic approach to studying these instabilities. A case of high-{beta} plasma ({beta} is the ratio of plasma pressure to the magnetic field pressure) and the modes with parallel phase velocity much smaller than the sound velocity is particularly emphasized and considered in the quasi-incompressible approximation. It is shown that this approximation is more adequate than the Boussinesq approximation. Both these approximations lead to the same results for aperiodical instabilities of the axisymmetric modes which are hybrids of the magnetorotational and convective instabilities. On the other hand, the Boussinesq approximation overlooks the heat-conductivity-induced instabilities predicted by the quasi-incompressible approximation describing the dissipative excitation of the slow magnetoacoustic and Alfven waves. Non-axisymmetric aperiodical instabilities are considered. It is shown that, for such modes, the role of convective instabilities is greater than for the magnetorotational instability.

Mikhailovskii, A. B.; Smolyakov, A. I. [Russian Research Centre Kurchatov Institute, Institute of Nuclear Fusion (Russian Federation); Lominadze, J. G. [Kharadze Abastumani National Astrophysical Observatory (Georgia); Churikov, A. P. [Syzran Branch of Samara Technical University (Russian Federation); Pustovitov, V. D. [Russian Research Centre Kurchatov Institute, Institute of Nuclear Fusion (Russian Federation); Kharshiladze, O. V. [Nodia Institute of Geophysics (Georgia)

2009-08-15T23:59:59.000Z

330

Modeling heat conduction and radiation transport with the diffusion equation in  

NLE Websites -- All DOE Office Websites (Extended Search)

heat conduction and radiation transport with the diffusion equation in NIF ALE-AMR heat conduction and radiation transport with the diffusion equation in NIF ALE-AMR This article has been downloaded from IOPscience. Please scroll down to see the full text article. 2010 J. Phys.: Conf. Ser. 244 022075 (http://iopscience.iop.org/1742-6596/244/2/022075) Download details: IP Address: 50.136.219.251 The article was downloaded on 18/04/2013 at 01:36 Please note that terms and conditions apply. View the table of contents for this issue, or go to the journal homepage for more Home Search Collections Journals About Contact us My IOPscience Modeling Heat Conduction and Radiation Transport with the Diffusion Equation in NIF ALE-AMR A.C. Fisher 1 , D.S. Bailey 1 , T.B. Kaiser 1 , B.T.N. Gunney 1 , N.D. Masters 1 , A.E. Koniges 2 , D.C. Eder 1 , R.W. Anderson 1 1: Lawrence Livermore National Laboratory,

331

Simulation of Static Flying Attitudes with Different Heat Transfer Models for a Flying-Height Control Slider with Thermal Protrusion  

E-Print Network (OSTI)

Zhang, S. , Bogy, D.B. : A heat transfer model for thermal ?A phenomenological heat transfer model for the molecular gasWong, C.H. : A generalized heat transfer model for thin ?lm

Chen, Du; Bogy, David B.

2010-01-01T23:59:59.000Z

332

5. Heat transfer Ron Zevenhoven  

E-Print Network (OSTI)

1/120 5. Heat transfer Ron Zevenhoven �bo Akademi University Thermal and Flow Engineering / Värme Three heat transfer mechanisms Conduction Convection Radiation 2/120 Pic: B�88 �bo Akademi University | Thermal and Flow Engineering | 20500 Turku | Finland #12;3/120 5.1 Conductive heat transfer �bo Akademi

Zevenhoven, Ron

333

Theory of interparticle correlations in dense, high-temperature plasmas. V. Electric and thermal conductivities  

Science Journals Connector (OSTI)

On the basis of the quantum-statistical formulation of electronic transport, we calculate the electric and thermal conductivities of plasmas in a wide range of densities and temperatures where it is essential to take into account the varied degrees of electron degeneracy and local-field corrections describing the strong Coulomb-coupling effects. The physical implications of the results are investigated through comparison with other theories and experiments. For utility in the practical applications, we derive the analytic formulas parametrizing the computed results accurately for the generalized Coulomb logarithms appearing in those conductivities.

Setsuo Ichimaru and Shigenori Tanaka

1985-09-01T23:59:59.000Z

334

The Impact of Thermal Conductivity and Diffusion Rates on Water Vapor Transport through Gas Diffusion Layers  

E-Print Network (OSTI)

Water management in a hydrogen polymer electrolyte membrane (PEM) fuel cell is critical for performance. The impact of thermal conductivity and water vapor diffusion coefficients in a gas diffusion layer (GDL) has been studied by a mathematical model. The fraction of product water that is removed in the vapour phase through the GDL as a function of GDL properties and operating conditions has been calculated and discussed. Furthermore, the current model enables identification of conditions when condensation occurs in each GDL component and calculation of temperature gradient across the interface between different layers, providing insight into the overall mechanism of water transport in a given cell design. Water transport mode and condensation conditions in the GDL components depend on the combination of water vapor diffusion coefficients and thermal conductivities of the GDL components. Different types of GDL and water removal scenarios have been identified and related to experimentally-determined GDL proper...

Burlatsky, S F; Gummallaa, M; Condita, D; Liua, F

2013-01-01T23:59:59.000Z

335

Analyzing the efficiency of a photovoltaic-thermal solar collector based on heat pipes  

Science Journals Connector (OSTI)

The structure of a photovoltaic/thermal solar collector based on aluminum heat pipes and ... , along with the results from analyzing its efficiency. Its optimum mode of operation is shown...

S. M. Khairnasov

2014-01-01T23:59:59.000Z

336

Energy Efficient Process Heating: Insulation and Thermal Mass Kevin Carpenter and Kelly Kissock  

E-Print Network (OSTI)

1 Energy Efficient Process Heating: Insulation and Thermal Mass Kevin Carpenter and Kelly Kissock-0210 Phone: (937) 229-2852 Fax: (937) 229-4766 Email: Kelly.Kissock@notes.udayton.edu ABSTRACT Open tanks

Kissock, Kelly

337

Use of Thermal Energy Storage to Enhance the Recovery and Utilization of Industrial Waste Heat  

E-Print Network (OSTI)

evaluation involving process data from 12 industrial plants to determine if thermal energy storage (TES) systems can be used with commercially available energy management equipment to enhance the recovery and utilization of industrial waste heat. Results...

McChesney, H. R.; Bass, R. W.; Landerman, A. M.; Obee, T. N.; Sgamboti, C. T.

1982-01-01T23:59:59.000Z

338

Heat transfer and thermal management of electric vehicle batteries with phase change materials  

Science Journals Connector (OSTI)

This paper examines a passive thermal management system for electric vehicle batteries, consisting of encapsulated phase change material ( ... process to absorb the heat generated by a battery. A new configuratio...

M. Y. Ramandi; I. Dincer; G. F. Naterer

2011-07-01T23:59:59.000Z

339

Thermal conductivity studies of novel nanofluids based on metallic silver decorated mesoporous silica nanoparticles  

SciTech Connect

Graphical abstract: - Highlights: • Metallic silver was decorated in mSiO{sub 2} with grafted hemiaminal functional groups. • Synthesized nanoparticles were used for preparation of glycerol based nanofluids. • The effect of temperature, weight fraction of mSiO{sub 2} and concentration of silver nanoparticles on thermal conductivity of nanofluids was investigated. - Abstract: In the present study, the mesoporous structure of silica (mSiO{sub 2}) nanoparticles as well as hemiaminal grafted mSiO{sub 2} decorated by metallic silver (Ag/mSiO{sub 2}) has been used for the preparation of glycerol based nanofluids. Structural and morphological characterization of the synthesized products have been carried out using Fourier transform infrared spectroscopy (FTIR), scanning electron microscope (SEM), X-ray diffraction (XRD), UV–vis spectroscopy, inductively coupled plasma (ICP) and N{sub 2} adsorption–desorption isotherms. The thermal conductivity and viscosity of the nanofluids have been measured as a function of temperature for various weight fractions and silver concentrations of mSiO{sub 2} and Ag/mSiO{sub 2} nanoparticles, respectively. The results show that the thermal conductivity of the nanofluids increase up to 9.24% as the weight fraction of mSiO{sub 2} increases up to 4 wt%. Also, increasing the percent of the silver decorated mSiO{sub 2} (Ag/mSiO{sub 2}) up to 2.98% caused an enhancement in the thermal conductivity of the base fluid up to 10.95%. Furthermore, the results show that the nanofluids have Newtonian behavior in the tested temperature range for various concentrations of nanoparticles.

Tadjarodi, Azadeh, E-mail: tajarodi@iust.ac.ir [Research Laboratory of Inorganic Materials Synthesis, Department of Chemistry, Iran University of Science and Technology, 16846-13114 Tehran (Iran, Islamic Republic of); Zabihi, Fatemeh [Research Laboratory of Inorganic Materials Synthesis, Department of Chemistry, Iran University of Science and Technology, 16846-13114 Tehran (Iran, Islamic Republic of); Chemistry and Nanotechnology Laboratory, National Center for Laser Science and Technology, Tehran (Iran, Islamic Republic of)

2013-10-15T23:59:59.000Z

340

THE JOURNAL OF CHEMICAL PHYSICS 140, 114502 (2014) Thermal conductivity of simple liquids: Origin of temperature and packing  

E-Print Network (OSTI)

. For example, in concen- trating solar power plants1 or in prospective Generation IV nuclear reactors,2THE JOURNAL OF CHEMICAL PHYSICS 140, 114502 (2014) Thermal conductivity of simple liquids: Origin dependence of T1/4 3/2 in the thermal conductivity of the simple Lennard-Jones (LJ) liquid is explored

Boyer, Edmond

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


341

Oxidation of Metals, Vol. 61, Nos. 3/4, April 2004 ( 2004) Thermal Conductivity, Phase Stability, and Oxidation  

E-Print Network (OSTI)

, and Oxidation Resistance of Y3Al5O12 (YAG)/Y2O3­ZrO2 (YSZ) Thermal-Barrier Coatings Y. J. Su, R. W. Trice,# K oxidation resistance while maintaining low thermal conductivity and good phase stability. Padture) is proposed. The objective of this work is to quantify the effect of YAG on thermal resistance, long

Trice, Rodney W.

342

Phonon-hopping thermal conduction in quantum dot superlattices Manu Shamsa, Weili Liu, and Alexander A. Balandina  

E-Print Network (OSTI)

or polycrystalline materials in terms of thermal transport. © 2005 American Institute of Physics. DOI: 10 strongly depends on interface conditions, is considered as a major thermal resistive mecha- nismPhonon-hopping thermal conduction in quantum dot superlattices Manu Shamsa, Weili Liu

343

Electron thermal conduction as a possible mechanism to make the inner heliosheath thnner  

E-Print Network (OSTI)

We show that the electron thermal conductivity may strongly affect the heliosheath plasma flow and the global pattern of the solar wind (SW) interaction with the local interstellar medium (LISM). In particular, it leads to strong reduction of the inner heliosheath thickness that makes possible to explain (qualitatively) why Voyager 1 (V1) has crossed the heliopause at unexpectedly small heliocentric distance of 122 AU. To estimate the effect of thermal conductivity we consider a limiting case when thermal conduction is very effective. To do that we assume the plasma flow in the entire heliosphere is nearly isothermal. Due to this effect, the heliospheric distance of the termination shock has increased by about 15 AU in V1 direction compared to the adiabatic case with gamma = 5/3. The heliospheric distance of the heliopause has decreased by about 27 AU. As a result, the thickness of the inner heliosheath in the model has decreased by about 42 AU and become equal to 32 AU.

Izmodenov, V V; Ruderman, M S

2014-01-01T23:59:59.000Z

344

Improvement by heating of the electronic conductivity of cobalt spinel phases, electrochemically synthesized in various electrolytes  

SciTech Connect

The nature of the alkaline electrolyte (based on KOH, NaOH, LiOH), in which Co{sub 3}O{sub 4} spinel type phases are synthesized by electrooxidation of CoO, is shown to play a key role on the composition, the structure and the electronic conductivity of the materials. In the materials, prepared in pure LiOH electrolyte or in mixed ternary electrolyte (KOH, NaOH, LiOH), Co{sup 4+} ions are present in the octahedral framework, which entails electronic delocalization in the cobalt T{sub 2g} band and a high conductivity. The structure of the sample, synthesized in KOH, is on the opposite closer to that of ideal Co{sub 3}O{sub 4}, with only Co{sup 3+} in the octahedral sublattice, which leads to a semi-conducting behavior. Whatever the initial material, a thermal treatment induces an increase of the Co{sup 4+}/Co{sup 3+} ratio in the octahedral network, resulting in a significant increase of the electronic conductivity. - Graphical abstract: In 'Co{sub 3}O{sub 4}' type spinel phases synthesized by eleectrooxidation, the nature of the alkaline electrolyte allows to monitor the amounts of hydrogen and lithium, inserted in spinel framework and therefore the electronic conductivity. Whatever the initial synthesis electrolyte, a moderate thermal treatment of the materials induces a significant increase of the electronic conductivity, due to a structural reorganization (illustrated by the evolution of the cell parameter) and an increase of the Co{sup 4+}/Co{sup 3+} ratio in the octahedral framework.

Douin, Myriam [CNRS, ICMCB, 87, Av. Dr. A. Schweitzer, 33608 Pessac Cedex (France); Universite de Bordeaux, ICMCB, ENSCPB, F33608 Pessac Cedex (France); SAFT - Direction de la Recherche 111-113 Boulevard Alfred Daney, 33074 Bordeaux Cedex (France); Guerlou-Demourgues, Liliane, E-mail: guerlou@icmcb-bordeaux.cnrs.f [CNRS, ICMCB, 87, Av. Dr. A. Schweitzer, 33608 Pessac Cedex (France); Universite de Bordeaux, ICMCB, ENSCPB, F33608 Pessac Cedex (France); Menetrier, Michel; Bekaert, Emilie [CNRS, ICMCB, 87, Av. Dr. A. Schweitzer, 33608 Pessac Cedex (France); Universite de Bordeaux, ICMCB, ENSCPB, F33608 Pessac Cedex (France); Goubault, Lionel; Bernard, Patrick [SAFT - Direction de la Recherche 111-113 Boulevard Alfred Daney, 33074 Bordeaux Cedex (France); Delmas, Claude [CNRS, ICMCB, 87, Av. Dr. A. Schweitzer, 33608 Pessac Cedex (France); Universite de Bordeaux, ICMCB, ENSCPB, F33608 Pessac Cedex (France)

2009-05-15T23:59:59.000Z

345

SENSIBLE HEAT STORAGE FOR A SOLAR THERMAL POWER PLANT  

E-Print Network (OSTI)

with Sensible- Heat Storage Solar Power Plant with Sulfurof the Solar Power Plant Storage-Vessel Design, . . . . .System for Chemical Storage of Solar Energy. UC Berkeley,

Baldwin, Thomas F.

2011-01-01T23:59:59.000Z

346

Swimming pools as heat sinks for air conditioners: Model design and experimental validation for natural thermal behavior of the pool  

Science Journals Connector (OSTI)

Swimming pools as thermal sinks for air conditioners could save approximately 40% on peak cooling power and 30% of overall cooling energy, compared to standard residential air conditioning. Heat dissipation from pools in semi-arid climates with large diurnal temperature shifts is such that pool heating and space cooling may occur concurrently; in which case heat rejected from cooling equipment could directly displace pool heating energy, while also improving space cooling efficiency. The performance of such a system relies on the natural temperature regulation of swimming pools governed by evaporative and convective heat exchange with the air, radiative heat exchange with the sky, and conductive heat exchange with the ground. This paper describes and validates a model that uses meteorological data to accurately predict the hourly temperature of a swimming pool to within 1.1 °C maximum error over the period of observation. A thorough review of literature guided our choice of the most appropriate set of equations to describe the natural mass and energy exchange between a swimming pool and the environment. Monitoring of a pool in Davis, CA, was used to confirm the resulting simulations. Comparison of predicted and observed pool temperature for all hours over a 56 day experimental period shows an R-squared relatedness of 0.967.

Jonathan Woolley; Curtis Harrington; Mark Modera

2011-01-01T23:59:59.000Z

347

Thermal Solar Energy Systems for Space Heating of Buildings  

E-Print Network (OSTI)

to compensate the deficit. In this case a traditional solar heating system having the same characteristics with regard to the solar collecting area and the volume of storage tank is used. It can be concluded that the space heating system using a solar energy...

Gomri, R.; Boulkamh, M.

2010-01-01T23:59:59.000Z

348

Potentials of Demand Side Management Using Heat Pumps with Building Mass as a Thermal Storage  

Science Journals Connector (OSTI)

Abstract Within this work, load-shifting possibilities of heat pumps in residential buildings as well as its influencing and limiting factors are displayed. The intermediate storage is achieved by using the thermal mass of the building so the heat supply can be postponed from the heat demand for a certain period, depending on the characteristics of the building. No additional water storage is considered.

Charlotte Ellerbrok

2014-01-01T23:59:59.000Z

349

The flow and heat transfer characteristics of multi-thermal fluid in horizontal wellbore coupled with flow in heavy oil reservoirs  

Science Journals Connector (OSTI)

Abstract As a new improved oil-recovery technique, multi-thermal fluid injection technology through a horizontal well has been widely used in the development process of heavy oil reservoirs. The flow and heat transfer characteristic of multi-thermal fluid in horizontal wellbore is significantly important for the productivity evaluation and parameters design of the horizontal well. Considering the specific physical properties of multi-thermal fluid, fluid absorption in perforation holes and pressure drop characteristics along the horizontal wellbore, this paper developed the flow and heat transfer model of multi-thermal fluid in perforated horizontal wellbore. In order to evaluate the heating effect of the multi-thermal fluid, a concept of effective heating length of a horizontal well is proposed. Then, a sensitivity analysis process is performed to study the influence of reservoir/fluid parameters and operating parameters on the flowing process of multi-thermal fluid in horizontal wellbore. Simultaneously, using the method of orthogonal numerical test, differential analysis and variance analysis are also conducted. Results show that the flowing process of multi-thermal fluid in horizontal wellbore includes a single-phase flowing process and a gas–liquid two-phase flowing process. The influence of oil viscosity on the flow and heat transfer characteristics of multi-thermal fluid in horizontal wellbore is most significant. Thereafter, the solution of our semi-analytical model is compared against the test results of an actual horizontal well from an oilfield in China. It is shown that the model results are in good agreement with the real test results. This model could be used to calculate and predict the flow and heat transfer characteristics of multi-thermal fluid (or saturated steam) in a perforated horizontal wellbore.

Xiaohu Dong; Huiqing Liu; Zhaoxiang Zhang; Changjiu Wang

2014-01-01T23:59:59.000Z

350

Active charge/passive discharge solar heating systems: thermal analysis  

SciTech Connect

The performance of active charge/passive discharge solar space-heating systems is analyzed. This type of system combines liquid-cooled solar collector panels with a massive integral storage component that passively heats the building interior by radiation and free convection. The TRNSYS simulation program is used to evaluate system performance and to provide input for the development of a simplified analysis method. This method, which provides monthly calculations of delivered solar energy, is based on Klein's Phi-bar procedure and data from hourly TRNSYS simulations. The method can be applied to systems using a floor slab, a structural wall, or a water tank as the storage component. Important design parameters include collector area and orientation, building heat loss, collector and heat-exchanger efficiencies, storage capacity, and storage to room coupling.

Swisher, J.

1981-01-01T23:59:59.000Z

351

NOTES AND DISCUSSIONS Note on thermal heating efficiency  

E-Print Network (OSTI)

. This is the conversion problem faced in every home, where one has heat from a gas, oil, wood, or coal flame but wants, Washington University, St. Louis, Missouri 63130 Received 25 April 2002; accepted for publication 26 July

Rodriguez, Carlos

352

Heat conduction: a telegraph-type model with self-similar behavior of solutions II  

E-Print Network (OSTI)

In our former study (J. Phys. A: Math. Theor. 43, (2010) 325210 or arXiv:1002.0999v1 [math-ph]) we introduced a modified Fourier-Cattaneo law and derived a non-autonomous telegraph-type heat conduction equation which has desirable self-similar solution. Now we present a detailed in-depth analysis of this model and discuss additional analytic solutions for different parameters. The solutions have a very rich and interesting mathematical structure due to various special functions.

I. F. Barna; R. Kersner

2010-09-30T23:59:59.000Z

353

Effects of preheating and highly heat-conductive brick on coke quality  

SciTech Connect

In replacing the coke ovens available currently, the introduction of a combined technique of a preheated coal charging method (preheating temperature:175 C) and the use of highly heat-conductive brick is under examination for raising the productivity of coke ovens. With such background, a study of the effects of this combined technique on the coke quality, especially the coke size was conducted. The experimental results revealed that the primary size of coke produced by the combined technique is noticeably larger than that of the coke made from wet coal and after five revolutions of drum (equivalent to mechanical impact given at a time of dropping from coke oven chamber to wharf), the coke size reduces even compared with an ordinary coke. This may be due to the fact that the coke produced by the combined technique includes a lot of fissures inside the coke lump.

Fukuda, K.; Arima, T. [Nippon Steel Corp., Chiba (Japan). Process Technology, Research Labs.

1995-12-31T23:59:59.000Z

354

E-Print Network 3.0 - ac conductivity studies Sample Search Results  

NLE Websites -- All DOE Office Websites (Extended Search)

Conductivity, Molecular... Dynamics Simulation, Thermal Conductance ABSTRACT Several heat transfer problems related to single... function between carbon and carbon within a...

355

First-Principles Determination of Ultrahigh Thermal Conductivity of Boron Arsenide: A Competitor for Diamond?  

Science Journals Connector (OSTI)

We have calculated the thermal conductivities (?) of cubic III-V boron compounds using a predictive first principles approach. Boron arsenide is found to have a remarkable room temperature ? over 2000??W?m-1?K-1; this is comparable to those in diamond and graphite, which are the highest bulk values known. We trace this behavior in boron arsenide to an interplay of certain basic vibrational properties that lie outside of the conventional guidelines in searching for high ? materials, and to relatively weak phonon-isotope scattering. We also find that cubic boron nitride and boron antimonide will have high ? with isotopic purification. This work provides new insight into the nature of thermal transport at a quantitative level and predicts a new ultrahigh ? material of potential interest for passive cooling applications.

L. Lindsay; D. A. Broido; T. L. Reinecke

2013-07-08T23:59:59.000Z

356

Temperature Dependent Thermal Conductivity of Si/SiC Amorphous Multilayer Films  

SciTech Connect

The cross-plane thermal conductivity of 22 nm period Si/SiC amorphous multilayer films deposited by magnetron sputtering and measured using a differential 3{omega} method was found to decrease from 2.0 W/mK at 300 K to 1.1 W/mK at 80 K. Structural disorder in each of the constituent layers of the amorphous multilayer films was confirmed by high resolution transmission electron microscopy. Estimations of the relative contributions of interface and intrinsic layer thermal resistance based on microscopic phonon transport models indicate that mean free path reductions induced by the structural disorder within the multilayer films are responsible for the observed experimental trends.

Mazumder, M.; Solovyov, S.; Borca-Tasciuc, T.; Teehan, S.C.; Stinzianni, E.; Efstathiadis, H.

2010-03-01T23:59:59.000Z

357

Thermal heat radiation, near-field energy density and near-field radiative heat transfer of coated materials  

E-Print Network (OSTI)

We investigate the thermal radiation and thermal near-field energy density of a metal-coated semi-infinite body for different substrates. We show that the surface polariton coupling within the metal coating leads to an enhancement of the TM-mode part of the thermal near-field energy density when a polar substrate is used. In this case the result obtained for a free standing metal film is retrieved. In contrast, in the case of a metal substrate there is no enhancement in the TM-mode part, as can also be explained within the framework of surface plasmon coupling within the coating. Finally, we discuss the influence of the enhanced thermal energy density on the near-field radiative heat transfer between a simple semi-infinite and a coated semi-infinite body for different material combinations.

Svend-Age Biehs

2011-03-15T23:59:59.000Z

358

Domestic demand-side management (DSM): Role of heat pumps and thermal energy storage (TES) systems  

Science Journals Connector (OSTI)

Heat pumps are seen as a promising technology for load management in the built environment, in combination with the smart grid concept. They can be coupled with thermal energy storage (TES) systems to shift electrical loads from high-peak to off-peak hours, thus serving as a powerful tool in demand-side management (DSM). This paper analyzes heat pumps with radiators or underfloor heating distribution systems coupled with TES with a view to showing how a heat pump system behaves and how it influences the building occupants' thermal comfort under a DSM strategy designed to flatten the shape of the electricity load curve by switching off the heat pump during peak hours (16:00–19:00). The reference scenario for the analysis was Northern Ireland (UK). The results showed that the heat pump is a good tool for the purposes of DSM, also thanks to the use of TES systems, in particular with heating distribution systems that have a low thermal inertia, e.g. radiators. It proved possible to achieve a good control of the indoor temperature, even if the heat pump was turned off for 3 h, and to reduce the electricity bill if a “time of use” tariff structure was adopted.

A. Arteconi; N.J. Hewitt; F. Polonara

2013-01-01T23:59:59.000Z

359

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

DOE Patents (OSTI)

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.

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

360

Gold-titania interface toughening and thermal conductance enhancement using an organophosphonate nanolayer  

SciTech Connect

We demonstrate that a mercaptan-terminated organophosphonate nanolayer at gold-titania interfaces can give rise to two- to three-fold enhancement in the interfacial fracture toughness and thermal conductance. Electron spectroscopy reveals that interfacial delamination occurs at the metal-molecule interface near the gold-sulfur bonds, consistent with density functional theory calculations of bond energies. Qualitative correlation between interfacial fracture toughness and bond energies suggest that organophosphonate nanolayers are resilient to humidity-induced degradation. These results, and the versatility of organophosphonates as surface functionalization agents for technologically relevant materials, unlock uncharted avenues for molecular engineering of interfaces in materials and devices for a variety of applications.

Chow, Philippe K.; O'Brien, Peter; Ramanath, Ganpati [Rensselaer Polytechnic Institute, Department of Materials Science and Engineering, Troy, New York 12180 (United States)] [Rensselaer Polytechnic Institute, Department of Materials Science and Engineering, Troy, New York 12180 (United States); Cardona Quintero, Y.; Ramprasad, R. [Materials Science and Engineering, University of Connecticut, Storrs, Connecticut 06269 (United States)] [Materials Science and Engineering, University of Connecticut, Storrs, Connecticut 06269 (United States); Hubert Mutin, P. [Institut Charles Gerhardt Montpellier, UMR 5253 CNRS-UM2-ENSCM-UM1, Universite Montpellier 2, CC 1701, Place Eugene Bataillon, 34095 Montpellier Cedex 5 (France)] [Institut Charles Gerhardt Montpellier, UMR 5253 CNRS-UM2-ENSCM-UM1, Universite Montpellier 2, CC 1701, Place Eugene Bataillon, 34095 Montpellier Cedex 5 (France); Lane, Michael [Chemistry Department, Emory and Henry College, Emory, Virginia 24327 (United States)] [Chemistry Department, Emory and Henry College, Emory, Virginia 24327 (United States)

2013-05-20T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


361

On the dynamical Rayleigh-Taylor instability in compressible viscous flows without heat conductivity  

E-Print Network (OSTI)

We investigate the instability of a smooth Rayleigh-Taylor steady-state solution to compressible viscous flows without heat conductivity in the presence of a uniform gravitational field in a bounded domain $\\Omega\\subset{\\mathbb R}^3$ with smooth boundary $\\partial\\Omega$. We show that the steady-state is linearly unstable by constructing a suitable energy functional and exploiting arguments of the modified variational method. Then, based on the constructed linearly unstable solutions and a local well-posedness result of classical solutions to the original nonlinear problem, we further reconstruct the initial data of linearly unstable solutions to be the one of the original nonlinear problem and establish an appropriate energy estimate of Gronwall-type. With the help of the established energy estimate, we show that the steady-state is nonlinearly unstable in the sense of Hadamard by a careful bootstrap argument. As a byproduct of our analysis, we find that the compressibility has no stabilizing effect in the linearized problem for compressible viscous flows without heat conductivity.

Fei Jiang; Song Jiang

2014-03-20T23:59:59.000Z

362

Developing Low-Conductance Window Frames: Capabilities and Limitations of Current Window Heat Transfer Design Tools  

E-Print Network (OSTI)

860. Batchelor, G.K. 1954. Heat transfer by free convectionfree convection. In: Heat Transfer and Turbulent BuoyantHEAT2, A PC-program for heat transfer in two dimensions.

Gustavsen, Arild

2009-01-01T23:59:59.000Z

363

Simulation of Infrared Laser Heating of Silica Using Heat Conduction and Multifrequency Radiation Diffusion Equations Adapted for Homogeneous Refractive Lossy Media  

SciTech Connect

Localized, transient heating of materials using micro-scale, highly absorbing laser light has been used in many industries to anneal, melt and ablate material with high precision. Accurate modeling of the relative contributions of conductive, convective and radiative losses as a function of laser parameters is essential to optimizing micro-scale laser processing of materials. In bulk semi-transparent materials such as silicate glass melts, radiation transport is known to play a significantly larger role as the temperature increases. Conventionally, radiation is treated in the frequency-averaged diffusive limit (Rosseland approximation). However, the role and proper treatment of radiative processes under rapidly heated, high thermal gradient conditions, often created through laser-matter interactions, is at present not clear. Starting from the radiation transport equation for homogeneous, refractive lossy media, they derive the corresponding time-dependent multi-frequency diffusion equations. Zeroth and first moments of the transport equation couple the energy density, flux and pressure tensor. The system is closed by neglecting the temporal derivative of the flux and replacing the pressure tensor by its diagonal analogue. The radiation equations are coupled to a diffusion equation for the matter temperature. They are interested in modeling infrared laser heating of silica over sub-millimeter length scales, and at possibly rapid rates. Hence, in contrast to related work, they retain the temporal derivative of the radiation field. They derive boundary conditions at a planar air-silica interface taking account of reflectivities obtained from the Fresnel relations that include absorption. The effect of a temperature-dependent absorption index is explored through construction of a multi-phonon dielectric function that includes mode dispersion. The spectral dimension is discretized into a finite number of intervals yielding a system of multigroup diffusion equations. Simulations are presented. To demonstrate the bulk heat loss due to radiation and the effect of the radiation's temporal derivative, they model cooling of a silica slab, initially at 2500 K, for 10 s. Retaining the derivative enables correctly modeling the loss of photons initially present in the slab. Other simulations model irradiating silica discs (of approximately 5 mm radii and thickness) with a CO2 laser: {lambda} = 10.59 and 4.6 um, Gaussian profile, r{sub 0} = 0.5 mm for 1/e decay. By surrounding the disks in room-temperature air, they make use of the boundary conditions described above.

Shestakov, A I; Matthews, M J; Vignes, R M; Stolken, J S

2010-10-28T23:59:59.000Z

364

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

E-Print Network (OSTI)

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

Roshandell, Melina

2013-01-01T23:59:59.000Z

365

Lattice Boltzmann modeling of the effective thermal conductivity for fibrous materials  

E-Print Network (OSTI)

for fluid-solid conjugate heat transfer. Internationaleffectively the fluid-solid conjugate heat transfer [30],for the fluid-solid conjugate heat transfer problem [30],

Wang, Moran; He, Jihuan; Yu, Jianyong; Pan, Ning

2007-01-01T23:59:59.000Z

366

When it comes to transporting energy, nature has two vital tools at its disposal: conduction by heat and by  

E-Print Network (OSTI)

When it comes to transporting energy, nature has two vital tools at its disposal: conduction by heat and by electricity. But these two phenomena have never been treated equally by scientists that have transformed many aspects of our lives. But similar devices that allow the flow of heat

Li, Baowen

367

Efficient Phase-Change Materials: Development of a Low-Cost Thermal Energy Storage System Using Phase-Change Materials with Enhanced Radiation Heat Transfer  

SciTech Connect

HEATS Project: USF is developing low-cost, high-temperature phase-change materials (PCMs) for use in thermal energy storage systems. Heat storage materials are critical to the energy storage process. In solar thermal storage systems, heat can be stored in these materials during the day and released at night—when the sun is not out—to drive a turbine and produce electricity. In nuclear storage systems, heat can be stored in these materials at night and released to produce electricity during daytime peak-demand hours. Most PCMs do not conduct heat very well. Using an innovative, electroless encapsulation technique, USF is enhancing the heat transfer capability of its PCMs. The inner walls of the capsules will be lined with a corrosion-resistant, high-infrared emissivity coating, and the absorptivity of the PCM will be controlled with the addition of nano-sized particles. USF’s PCMs remain stable at temperatures from 600 to 1,000°C and can be used for solar thermal power storage, nuclear thermal power storage, and other applications.

None

2011-12-05T23:59:59.000Z

368

A Gas Chromatography–Thermal Conductivity Detection Method for Helium Detection in Postmortem Blood and Tissue Specimens  

Science Journals Connector (OSTI)

......victim's head, although some internet sources recommend use of...for volatiles and drugs of abuse. The cause of death was...Discussion of the Influence of the Internet. Am. J. Forensic Med...Suicide Thermal Conductivity Young Adult...

Jason E. Schaff; Roman P. Karas; Laureen Marinetti

2012-03-01T23:59:59.000Z

369

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

E-Print Network (OSTI)

pipes in high-temperature solar-energy power plants, thanks to its large thermal conductivity, which Laboratories, Albuquerque, New Mexico 87185, USA (Received 23 May 2011; published 4 August 2011) We report

Alfè, Dario

370

Thermal conductivity of the insulation system of the stator winding of a high-power turbogenerator with air cooling  

Science Journals Connector (OSTI)

Values of the thermal-conductivity coefficient of specimens of the frame insulation manufactured from pre- and unimpregnated, mica-containing tapes are determined. It is established that the tape structure, te...

A. Sh. Azizov; A. M. Andreev; A. M. Kostel’ov…

2009-03-01T23:59:59.000Z

371

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

E-Print Network (OSTI)

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...

Mckenna, Sean

2010-01-15T23:59:59.000Z

372

An investigation into the thermal properties of selected sensible and latent heat storage materials  

E-Print Network (OSTI)

in the latent heat of fusion. Considerable work has been done in analyzing latent heat storage systems. Telkes and Raymond [lj did early work with a sodium sulfate system using sealed drums. iVore recent experimental work was conducted with other salt...

Wood, Stanley Clayton

1982-01-01T23:59:59.000Z

373

Thermal behavior of spiral fin-and-tube heat exchanger having fly ash deposit  

SciTech Connect

This research investigates the effect of fly-ash deposit on thermal performance of a cross-flow heat exchanger having a set of spiral finned-tubes as a heat transfer surface. A stream of warm air having high content of fly-ash is exchanging heat with a cool water stream in the tubes. In this study, the temperature of the heat exchanger surface is lower than the dew point temperature of air, thus there is condensation of moisture in the air stream on the heat exchanger surface. The affecting parameters such as the fin spacing, the air mass flow rate, the fly-ash mass flow rate and the inlet temperature of warm air are varied while the volume flow rate and the inlet temperature of the cold water stream are kept constant at 10 l/min and 5 C, respectively. From the experiment, it is found that as the testing period is shorter than 8 h the thermal resistance due to the fouling increases with time. Moreover, the deposit of fly-ash on the heat transfer surface is directly proportional to the dust-air ratio and the amount of condensate on heat exchange surface. However, the deposit of fly-ash is inversely proportional to the fin spacing. The empirical model for evaluating the thermal resistance is also developed in this work and the simulated results agree well with those of the measured data. (author)

Nuntaphan, Atipoang [Thermal Technology Research Laboratory, Mae Moh Training Center, Electricity Generating Authority of Thailand, Mae Moh, Lampang 52220 (Thailand); Kiatsiriroat, Tanongkiat [Department of Mechanical Engineering, Chiang Mai University, Chiang Mai 50200 (Thailand)

2007-08-15T23:59:59.000Z

374

An experimental investigation of thermal contact conductance across carbon fiber/epoxy resin composites as a function of interface pressure  

E-Print Network (OSTI)

AN EXPERIMENTAL INVESTIGATION OF THERMAL CONTACT CONDUCTANCE ACROSS CARBON FIBER/EPOXY RESIN COMPOSITES AS A FUNCTION OF INTERFACE PRESSURE A Thesis by MICHAEL EVERETT RHOADES Submitted to the Office of Graduate Studies of Texas A...&M University in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE December 1989 Major Subject: Mechanical Engineering AN EXPERIMENTAL INVESTIGATION OF THERMAL CONTACT CONDUCTANCE ACROSS CARBON FIBER/EPOXY RESIN COMPOSITES AS A...

Rhoades, Michael Everett

1989-01-01T23:59:59.000Z

375

Minor ion heating in spectra of linearly and circularly polarized Alfvén waves: Thermal and non-thermal motions associated with perpendicular heating  

SciTech Connect

Minor ion (such as He{sup 2+}) heating via nonresonant interaction with spectra of linearly and circularly polarized Alfvén waves (LPAWs and CPAWs hereafter) is studied. The obtained analytic solutions are in good agreement with the simulation results, indicating that newborn ions are heated by low-frequency Alfvén waves with finite amplitude in low-beta plasmas such as the solar corona. The analytic solutions also reproduce the preferential heating of heavy ions in the solar wind. In the presence of parallel propagating Alfvén waves, turbulence-induced particle motion is clearly observed in the wave (magnetic field) polarized directions. After the waves diminish, the newborn ions are heated, which is caused by the phase difference (randomization) between ions due to their different parallel thermal motions. The heating is dominant in the direction perpendicular to the ambient magnetic field. The perpendicular heating, ?=(T{sub i?}{sup R}?T{sub i0?}{sup R})/T{sub i0?}{sup R} (where T{sub i0?}{sup R} and T{sub i?}{sup R} are the perpendicular temperature of species i before and after genuine heating, respectively), in the spectrum of CPAWs is a factor of two stronger than that of LPAWs. Moreover, we also study the effect of field-aligned differential flow speed of species i relative to H{sup +}, ?v{sub ip}=(v{sub i}?v{sub p})·B/|B| (where v{sub i} and v{sub p} denote vector velocities of the H{sup +} and species i, respectively), on the perpendicular heating. It reveals that large drift speed, v{sub d}=?v{sub ip}, has an effect on reducing the efficiency of perpendicular heating, which is consistent with observations.

Dong, Chuanfei, E-mail: dcfy@umich.edu [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States) [Department of Atmospheric, Oceanic and Space Sciences, University of Michigan, Ann Arbor, Michigan 48109 (United States); Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)

2014-02-15T23:59:59.000Z

376

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

E-Print Network (OSTI)

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

Harmon, Julie P.

377

Numerical simulation of heat transfer performance of an air-cooled steam condenser in a thermal power plant  

Science Journals Connector (OSTI)

Numerical simulation of the thermal-flow characteristics and heat transfer performance is made of an air-cooled steam condenser (ACSC) in a thermal power plant by considering the effects of ambient wind speed and...

Xiufeng Gao; Chengwei Zhang; Jinjia Wei; Bo Yu

2009-09-01T23:59:59.000Z

378

The Thermal Fatigue Life Prediction of Diesel Engine Heating Components by the Strain-Range Partitioning Method  

Science Journals Connector (OSTI)

In this paper, first the loading condition of thermal load of marine diesel engine is analyzed, and then the stress-strain ... carried on the thermal fatigue life prediction of diesel engine heating components by...

Senior Engineer Gu Zetong; Hu Gan…

1987-01-01T23:59:59.000Z

379

Review of combined photovoltaic/thermal collector: solar assisted heat pump system options  

SciTech Connect

The advantages of using photovoltaic (PV) and combined photovoltaic/thermal (PV/T) collectors in conjunction with residential heat pumps are examined. The thermal and electrical power requirements of similar residences in New York City and Fort Worth are the loads under consideration. The TRNSYS energy balance program is used to simulate the operations of parallel, series, and cascade solar assisted heat pump systems. Similar work involving exclusively thermal collectors is reviewed, and the distinctions between thermal and PV/T systems are emphasized. Provided the defrost problem can be satisfactorily controlled, lifecycle cost analyses show that at both locations the optimum collector area is less than 50 m/sup 2/ and that the parallel system is preferred.

Sheldon, D.B.; Russell, M.C.

1980-01-01T23:59:59.000Z

380

Thermal energy recovery of low grade waste heat in hydrogenation process; Återvinning av lågvärdig spillvärme från en hydreringsprocess.  

E-Print Network (OSTI)

?? The waste heat recovery technologies have become very relevant since many industrial plants continuously reject large amounts of thermal energy during normal operation which… (more)

Hedström, Sofia

2014-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


381

Using the reversability of the peltier effect to reduce the heat-scattering surfaces of thermal cooling batteries  

Science Journals Connector (OSTI)

We propose and analyze a method for significant reduction in the area of heat scattering surfaces in thermal cooling batteries, where the latter are used to cool....

E. K. Iordanishvili

1991-03-01T23:59:59.000Z

382

4th Generation District Heating (4GDH): Integrating smart thermal grids into future sustainable energy systems  

Science Journals Connector (OSTI)

Abstract This paper defines the concept of 4th Generation District Heating (4GDH) including the relations to District Cooling and the concepts of smart energy and smart thermal grids. The motive is to identify the future challenges of reaching a future renewable non-fossil heat supply as part of the implementation of overall sustainable energy systems. The basic assumption is that district heating and cooling has an important role to play in future sustainable energy systems – including 100 percent renewable energy systems – but the present generation of district heating and cooling technologies will have to be developed further into a new generation in order to play such a role. Unlike the first three generations, the development of 4GDH involves meeting the challenge of more energy efficient buildings as well as being an integrated part of the operation of smart energy systems, i.e. integrated smart electricity, gas and thermal grids.

Henrik Lund; Sven Werner; Robin Wiltshire; Svend Svendsen; Jan Eric Thorsen; Frede Hvelplund; Brian Vad Mathiesen

2014-01-01T23:59:59.000Z

383

On choosing a nonlinear initial iterate for solving the 2-D 3-T heat conduction equations  

SciTech Connect

The 2-D 3-T heat conduction equations can be used to approximately describe the energy broadcast in materials and the energy swapping between electron and photon or ion. To solve the equations, a fully implicit finite volume scheme is often used as the discretization method. Because the energy diffusion and swapping coefficients have a strongly nonlinear dependence on the temperature, and some physical parameters are discontinuous across the interfaces between the materials, it is a challenge to solve the discretized nonlinear algebraic equations. Particularly, as time advances, the temperature varies so greatly in the front of energy that it is difficult to choose an effective initial iterate when the nonlinear algebraic equations are solved by an iterative method. In this paper, a method of choosing a nonlinear initial iterate is proposed for iterative solving this kind of nonlinear algebraic equations. Numerical results show the proposed initial iterate can improve the computational efficiency, and also the convergence behavior of the nonlinear iteration.

An Hengbin [High Performance Computing Center, Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)], E-mail: an_hengbin@iapcm.ac.cn; Mo Zeyao [High Performance Computing Center, Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)], E-mail: zeyao_mo@iapcm.ac.cn; Xu Xiaowen [High Performance Computing Center, Institute of Applied Physics and Computational Mathematics, Beijing 100088 (China)], E-mail: xwxu@iapcm.ac.cn; Liu Xu [Graduate School of China Academy of Engineering Physics, Beijing 100088 (China)], E-mail: ninad@sohu.com

2009-05-20T23:59:59.000Z

384

Thermal monitoring and optimization of geothermal district heating systems using artificial neural network: A case study  

Science Journals Connector (OSTI)

This paper deals with determine the energy and exergy efficiencies and exergy destructions for thermal optimization of a geothermal district heating system by using artificial neural network (ANN) technique. As a comprehensive case study, the Afyonkarahisar geothermal district heating system (AGDHS) in Afyonkarahisar/Turkey is considered and its actual thermal data as of average weekly data are collected in heating seasons during the period 2006–2010 for ANN based monitoring and thermal optimization. The measured data and calculated values are used at the design of Levenberg-Marquardt (LM) based multi-layer perceptron (MLP) in Matlab program. The results of the study are described graphically. The results show that the developed model is found to quickly predict the thermal performance and exergy destructions of the AGDHS with good accuracy. In addition, two main factors play important roles in the thermal optimization: (i) ambient temperature and (ii) flow rates in energy distribution cycle of the AGDHS. Various cases are investigated to determine how to change the energy and exergy efficiencies of the AGDHS for the temperature and flow rate. Finally, a monitoring and performance evaluation of a geothermal district heating system and its components by ANN will reduce the losses and human involvement and make the system more effective and efficient.

Ali Keçeba?; ?smail Yabanova

2012-01-01T23:59:59.000Z

385

Measurement of the Anisotropic Thermal Conductivity of Molybdenum Disulfide Single Crystal by the Time-resolved Magneto-optic Kerr Effect  

E-Print Network (OSTI)

with perpendicular magnetization serves as the heater and thermometer in the experiment. The low thermal conductivity for determining the thermal conductivity of materials but the sensitivity of TDTR to the lateral or in-plane thermal conductivity of a sample is low when conventional choices are made for laser spot sizes, #12

Cahill, David G.

386

Thermal conductance of graphene and dimerite Jin-Wu Jiang,1 Jian-Sheng Wang,1 and Baowen Li1,2,*  

E-Print Network (OSTI)

Thermal conductance of graphene and dimerite Jin-Wu Jiang,1 Jian-Sheng Wang,1 and Baowen Li1,2,* 1; published 20 May 2009 We investigate the phonon thermal conductance of graphene regarding the graphene sheet as the large-width limit of graphene strips in the ballistic limit. We find that the thermal conductance

Li, Baowen

387

Thermal conductivity and phonon linewidths of monolayer MoS{sub 2} from first principles  

SciTech Connect

Using ab initio calculations, we have investigated the phonon linewidths and the thermal conductivity (?) of monolayer MoS{sub 2}. ? for a typical sample size of 1??m is 83 W/m K at room temperature in the completely rough edge limit, suggesting ? is not a limiting factor for the electronic application of monolayer MoS{sub 2}. ? can be further increased by 30% in 10??m sized samples. Due to strong anharmonicity, isotope enhancement of room temperature ? is only 10% for 1??m sized samples. However, linewidths can be significantly reduced, for instance, for Raman active modes A{sub 1g} and E{sub 2g}{sup 1}, in isotopically pure samples.

Li, Wu, E-mail: wu.li.phys2011@gmail.com; Carrete, J.; Mingo, Natalio, E-mail: natalio.mingo@cea.fr [CEA-Grenoble, 17 Rue des Martyrs, Grenoble 38000 (France)] [CEA-Grenoble, 17 Rue des Martyrs, Grenoble 38000 (France)

2013-12-16T23:59:59.000Z

388

Non-thermal solar wind heating by supra-thermal ions  

Science Journals Connector (OSTI)

The effect of a new energy source due to energies transferred from supra-thermal secondary ions on the temperature profile of the solar wind has been considered. For this purpose ... solution of a tri-fluid model...

H. J. Fahr

1973-05-01T23:59:59.000Z

389

Power enhancement of heat engines via correlated thermalization in multilevel systems  

E-Print Network (OSTI)

We analyze a heat machine based on a periodically-driven quantum system permanently coupled to hot and cold baths. It is shown that the maximal power output of a degenerate $V$-type three-level heat engine is that generated by two independent two-level systems. For $N$ levels, this maximal enhancement is $(N-1)$-fold. Hence, level degeneracy is a thermodynamic resource that may effectively boost the power output. The efficiency, however, is not affected. We find that coherence is not an essential asset in multilevel-based heat machines. The existence of multiple thermalization pathways sharing a common ground state suffices for power enhancement.

David Gelbwaser-Klimovsky; Wolfgang Niedenzu; Paul Brumer; Gershon Kurizki

2014-11-05T23:59:59.000Z

390

Development and adaptation of conduction and radiation heat-transfer computer codes for the CFTL. [Core Flow Test Loop; RODCON; HOTTEL  

SciTech Connect

RODCON and HOTTEL are two computational methods used to calculate thermal and radiation heat transfer for the Core Flow Test Loop (CFTL) analysis efforts. RODCON was developed at ORNL to calculate the internal temperature distribution of the fuel rod simulator (FRS) for the CFTL. RODCON solves the time-dependent heat transfer equation in two-dimensional (R angle) cylindrical coordinates at an axial plane with user-specified radial material zones and time- and position-variant surface conditions at the FRS periphery. Symmetry of the FRS periphery boundary conditions is not necessary. The governing elliptic, partial differential heat equation is cast into a fully implicit, finite-difference form by approximating the derivatives with a forward-differencing scheme with variable mesh spacing. The heat conduction path is circumferentially complete, and the potential mathematical problem at the rod center can be effectively ignored. HOTTEL is a revision of an algorithm developed by C.B. Baxi at the General Atomic Company (GAC) to be used in calculating radiation heat transfer in a rod bundle enclosed in a hexagonal duct. HOTTEL uses geometric view factors, surface emissivities, and surface areas to calculate the gray-body or composite view factors in an enclosure having multiple reflections in a nonparticipating medium.

Conklin, J.C.

1981-08-01T23:59:59.000Z

391

Microsegregation effects on the thermal conductivity of silicon-germanium alloys  

SciTech Connect

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.

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

392

ThermalEngineeringLaboratory,VanderbiltUniversity Convection Heat Transfer of Nanofluids in Commercial  

E-Print Network (OSTI)

in Commercial Electronic Cooling Systems N.A. Roberts and D.G. Walker Department of Mechanical Engineering in real systems · Benefits of nanofluids ­ reduced sedimentation and viscosity ­ reduced damageThermalEngineeringLaboratory,VanderbiltUniversity Convection Heat Transfer of Nanofluids

Walker, D. Greg

393

Thermal Economic Analysis of an Underground Water Source Heat Pump System  

E-Print Network (OSTI)

The paper presents the thermal economic analysis of an underground water source heat pump system in a high school building based on usage per exergy cost as an evaluation standard, in which the black box model has been used and the cost...

Zhang, W.; Lin, B.

2006-01-01T23:59:59.000Z

394

DRAIN-BACK PROTECTED LOW-FLOW SOLAR HEATING SYSTEM WITH DISTRIBUTED ELEVATED THERMALLY STRATIFIED STORAGE  

Science Journals Connector (OSTI)

ABSTRACT Design considerations concerning a drain-back freeze and overheat protection system are given with emphasis on nitrogen management and thermal stratification of an elevated distributed storage. The actual system of GNT in Berg, Federal Republic of Germany is described. KEYWORDS Solar Heating; Freeze Protection; Overheat Protection; Drain-Back System;

W.B. VELTKAMP; J. VAN BERKEL; A.T. KEESMAN

1990-01-01T23:59:59.000Z

395

Numerical Simulation of Thermal Performance of Floor Radiant Heating System with Enclosed Phase Change Material  

E-Print Network (OSTI)

of the energy storage floor is designed,which places heat pipes in the enclosed phase change material (PCM) layer, without concrete in it. The PCM thermal storage time is studied in relation to the floor surface temperature under different low-temperature hot...

Qiu, L.; Wu, X.

2006-01-01T23:59:59.000Z

396

Thermal Energy Storage/Waste Heat Recovery Applications in the Cement Industry  

E-Print Network (OSTI)

, and the Portland Cement Association have studied the potential benefits of using waste heat recovery methods and thermal energy storage systems in the cement manufacturing process. This work was performed under DOE Contract No. EC-77-C-01-50S4. The study has been...

Beshore, D. G.; Jaeger, F. A.; Gartner, E. M.

1979-01-01T23:59:59.000Z

397

Heat advection versus conduction at the KTB: possible reasons for vertical variations in heat-flow density  

Science Journals Connector (OSTI)

......Deep Drilling Program (KTB): Site-selection Studies in the Oberpfalz...interpretation of thermal data from the Nevada test site.Open-File Report 82-973...interpretation of thermal data from the Nevada test site, Open-File Report 82-973......

Michael Jobmann; Christoph Clauser

1994-10-01T23:59:59.000Z

398

Mesoscopic simulations of phase distribution effects on the effective thermal conductivity of microgranular porous media.  

E-Print Network (OSTI)

Algorithm for Fluid-Solid Conjugate Heat Transfer. Int. J.effectively the fluid-solid conjugate heat transfer [28],for the fluid-solid conjugate heat transfer problem [28].

Wang, Moran; Pan, Ning; Wang, Jinku; Chen, Shiyi

2007-01-01T23:59:59.000Z

399

Mesoscopic simulations of phase distribution effects on the effective thermal conductivity of microgranular porous media  

E-Print Network (OSTI)

Algorithm for Fluid-Solid Conjugate Heat Transfer. Int. J.the solid-fluid conjugate heat transfer, which actuallywhen the fluid-solid conjugate heat transfer problem is

Wang, Moran Dr.; Pan, Ning; Wang, Jinku; Chen, Shiyi

2007-01-01T23:59:59.000Z

400

ESTIMATION OF IN-SITU THERMAL CONDUCTIVITIES FROM TEMPERATURE GRADIENT MEASUREMENTS  

E-Print Network (OSTI)

in the fluid, and the rate of heat transfer from the fluidSpi11ette t A.G~t "Heat Transfer During Hot Fluid Injectionin the fluid is solved, the heat transfer at the wall is

Hoang, V.T.

2010-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


401

Thermal conduction by dark matter with velocity and momentum-dependent cross-sections  

E-Print Network (OSTI)

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.

Aaron C. Vincent; Pat Scott

2013-11-08T23:59:59.000Z

402

Operational Performance Results of an Innovative Solar Thermal Cooling and Heating Plant  

Science Journals Connector (OSTI)

Solar thermal cooling and heating plants with single-effect sorption chillers/heat pumps promise primary energy savings compared to electric vapor compression chiller systems. Yet, the need of auxiliary electric a nd fossil energy for the operation and backup of the thermal cooling system possibly worsen the primary energy balance. An auspicious approach to overcome this problem is the application of a more efficient multi -stage sorption chiller with flexible operational modes. A pilot installation of that innovative solar thermal heating and cooling plant comprising a two stage absorption chiller/heat pump is presented. Beginning with the motivation and the system concept, a detailed analysis of the 2011/2012 cooling and heating periods is shown. The influence of the different system components – especially the absorption chiller – on the overall system performance is analyzed and a comparison to data from a detailed dynamic model is carried out. Recommendations for the improvement with respect to efficiency and economic aspects are given based on the installation process and the operational experience gained in the last 1 ½ years.

Manuel Riepl; Felix Loistl; Richard Gurtner; Martin Helm; Christian Schweigler

2012-01-01T23:59:59.000Z

403

The role of impact and radiogenic heating in the early thermal evolution of Mars  

E-Print Network (OSTI)

The planetary differentiation models of Mars are proposed that take into account core-mantle and core-mantle-crust differentiation. The numerical simulations are presented for the early thermal evolution of Mars spanning up to the initial 25 million years (Ma) of the early solar system, probably for the first time, by taking into account the radiogenic heating due to the short-lived nuclides, 26Al and 60Fe. The influence of impact heating during the accretion of Mars is also incorporated in the simulations. The early accretion of Mars would necessitate a substantial role played by the short-lived nuclides in its heating. 26Al along with impact heating could have provided sufficient thermal energy to the entire body to substantially melt and trigger planetary scale differentiation. This is contrary to the thermal models based exclusively on the impact heating that could not produce widespread melting and planetary differentiation. The early onset of the accretion of Mars perhaps within the initial ~1.5 Ma in t...

Sahijpal, S

2014-01-01T23:59:59.000Z

404

Heating of thermal non-equilibrium ions by Alfvén wave via nonresonant interaction  

SciTech Connect

Pickup of thermal non-equilibrium ions by Alfvén wave via nonresonant wave-particle interaction is investigated by means of analytical test-particle theory. Some interesting and new results are found. No matter what the initial velocity distribution is, if the background magnetic field, the Alfvén speed, and the Alfvén magnetic field are fixed, the average parallel velocity never changes when t??. Heating effects in the perpendicular and parallel direction just depend on the initial temperature, and the perpendicular temperature increase is more prominent. It is noted that the heating effect of thermal non-equilibrium ions (Kappa ions) is weaker than that of the Maxwellian. This phenomenon may be relative to the heating of ions in the solar corona as well as in some toroidal confinement fusion devices.

Liu, Hai-Feng; Wang, Shi-Qing [Southwestern Institute of Physics, Chengdu 610041 (China) [Southwestern Institute of Physics, Chengdu 610041 (China); The Engineering and Technical College of Chengdu University of Technology, Leshan 614000 (China); Li, Ke-Hua [The Engineering and Technical College of Chengdu University of Technology, Leshan 614000 (China)] [The Engineering and Technical College of Chengdu University of Technology, Leshan 614000 (China)

2013-10-15T23:59:59.000Z

405

Thermal and economical analysis of a central solar heating system with underground seasonal storage in Turkey  

Science Journals Connector (OSTI)

Thermal performance and economic feasibility of two types of central solar heating system with seasonal storage under four climatically different Turkey locations are investigated. The effects of storage volume and collector area on the thermal performance and cost are studied for three load sizes. The simulation model of the system consisting of flat plate solar collectors, a heat pump, under ground storage tank and heating load based on a finite element analysis and finite element code ANSYS™ is chosen as a convenient tool. In this study, the lowest solar fraction value for Trabzon (41°N) and the highest solar fraction value for Adana (37°N) are obtained. Based on the economic analysis, the payback period of system is found to be about 25–35 years for Turkey.

A. Ucar; M. Inalli

2005-01-01T23:59:59.000Z

406

Countermeasures to Microbiofouling in Simulated Ocean Thermal Energy Conversion Heat Exchangers with Surface and Deep Ocean Waters in Hawaii  

Science Journals Connector (OSTI)

...thermal energy from warm ocean waters. A small fraction...converted to electrical power and waste heat is rejected...water pumped from the ocean depth. Solar energy absorbed by the ocean surface provides the heat...Thermal losses, the power requirements to pump large...

Leslie Ralph Berger; Joyce A. Berger

1986-06-01T23:59:59.000Z

407

Low-temperature thermal conductivity of antiferromagnetic S?=?1/2 chain material CuCl{sub 2}·2((CH{sub 3}){sub 2}SO)  

SciTech Connect

We study the heat transport of S?=?1/2 chain compound CuCl{sub 2}·2((CH{sub 3}){sub 2}SO) along the b axis (vertical to the chain direction) at very low temperatures. The zero-field thermal conductivity (?) shows a distinct kink at about 0.9?K, which is related to the long-range antiferromagnetic (AF) transition. With applying magnetic field along the c axis, ?(H) curves also show distinct changes at the phase boundaries between the AF and the high-field disordered states. These results indicate a strong spin-phonon interaction and the magnetic excitations play a role in the b-axis heat transport as phonon scatterers.

Ke, W. P.; Zhang, F. B.; Zhao, Z. Y.; Fan, C.; Sun, X. F., E-mail: xfsun@ustc.edu.cn [Hefei National Laboratory for Physical Sciences at Microscale, University of Science and Technology of China, Hefei, Anhui 230026 (China); Shi, J. [Department of Physics, University of Science and Technology of China, Hefei, Anhui 230026 (China); Zhao, X., E-mail: xiazhao@ustc.edu.cn [School of Physical Sciences, University of Science and Technology of China, Hefei, Anhui 230026 (China)

2014-05-07T23:59:59.000Z

408

Thermophysical Properties of Heat Resistant Shielding Material  

SciTech Connect

This project was aimed at determining thermal conductivity, specific heat and thermal expansion of a heat resistant shielding material for neutron absorption applications. These data are critical in predicting the structural integrity of the shielding under thermal cycling and mechanical load. The measurements of thermal conductivity and specific heat were conducted in air at five different temperatures (-31 F, 73.4 F, 140 F, 212 F and 302 F). The transient plane source (TPS) method was used in the tests. Thermal expansion tests were conducted using push rod dilatometry over the continuous range from -40 F (-40 C) to 302 F (150 C).

Porter, W.D.

2004-12-15T23:59:59.000Z

409

Tunable thermal link  

DOE Patents (OSTI)

Disclosed is a device whereby the thermal conductance of a multiwalled nanostructure such as a multiwalled carbon nanotube (MWCNT) can be controllably and reversibly tuned by sliding one or more outer shells with respect to the inner core. As one example, the thermal conductance of an MWCNT dropped to 15% of the original value after extending the length of the MWCNT by 190 nm. The thermal conductivity returned when the tube was contracted. The device may comprise numbers of multiwalled nanotubes or other graphitic layers connected to a heat source and a heat drain and various means for tuning the overall thermal conductance for applications in structure heat management, heat flow in nanoscale or microscale devices and thermal logic devices.

Chang, Chih-Wei; Majumdar, Arunava; Zettl, Alexander K.

2014-07-15T23:59:59.000Z

410

Liquid Metal as a Heat Transport Fluid for Thermal Solar Power Applications  

Science Journals Connector (OSTI)

Abstract In order to increase the thermal efficiency and produce process heat for hydrogen production, the operating temperature of the heat transfer fluid in thermal solar plants needs to increase. In addition reaching 900 °C would also increase the heat storage density and the efficiency of the thermodynamic cycle by using a combined cycle for electricity production. The benefits of hydrogen (e.g., for fuel cells) and a more efficient thermodynamic cycle would allow a plant to have a higher energy output per square acre of land use, thereby increasing its economic competiveness. Today, solar thermal plants do not operate at these high temperatures due to the fact that conventional heat transport fluids begin to disintegrate around 600 °C [1,2]. For non-solar applications, low melting-temperature metals, such as wood's metal and lead- bismuth eutectic alloy, have been examined as heat-transport media, because of the large temperature ranges over which they remain liquid. Lead-bismuth eutectic alloy (LBE; 45% Pb, 55% Bi) melts at 125 °C and does not boil until 1670 °C, making it an ideal heat-transfer medium for application in thermal solar power [3]. The main obstacle to using LBE is finding structural materials that can withstand the harsh corrosion environments at high temperatures. In this work the key issues of materials exposed to liquid metal are described while initial data on carious steels tested in liquid metal are provided. While corrosion is a significant issue in this environment, mechanical failure of steels in liquid metal are discussed as well.

D. Frazer; E. Stergar; C. Cionea; P. Hosemann

2014-01-01T23:59:59.000Z

411

Compression of felt?type thermal insulation layer for underfloor heating system and floor impact sound  

Science Journals Connector (OSTI)

In Korea almost every house uses underfloor heating which has advantages of thermal comfort and energy efficiency. However when it is constructed for high?rise apartment houses it yields a problem in floor impact sound insulation. It accounts for the fact that a foam?type thermal insulator sandwiched between structural slab and heating floor functions as a spring and easily transmits impacts on the floor to the slab. In that case the system's transmissibility is determined by dynamic stiffness of the thermal insulation layer and the lower the dynamic stiffness is the more the floor impact is isolated. For that reason apartments construction companies are attempting to lower the dynamic stiffness of the thermal insulation layer for impact sound reduction. As part of the attempt felt?type materials with relatively low dynamic stiffness such as glass wool or polyester felt are considered as a substitution for the foam?type thermal insulator. However there is a possibility that compression of the felt?type materials would increase the dynamic stiffness and the impact sound insulation effect at early stage might be weakened in the long term. This paper investigates the correlation between gradual compression of the felt?type thermal insulation layer and the impact sound variation.

Tongjun Cho; Hyun?Min Kim

2008-01-01T23:59:59.000Z

412

Ultra-Low Thermal Conductivity in W/Al2O3 Nanolaminates  

E-Print Network (OSTI)

conversion (3). Conversely, the thermal resistance of interfaces degrades the performance of materials dissimilar materials may provide a route for the production of thermal barriers with ultra-low thermal and improve the performance of thermal bar- riers (2) and of materials used in thermoelec- tric energy

George, Steven M.

413

THERMAL NON-EQUILIBRIUM REVISITED: A HEATING MODEL FOR CORONAL LOOPS  

SciTech Connect

The location and frequency of events that heat the million-degree corona are still a matter of debate. One potential heating scenario is that the energy release is effectively steady and highly localized at the footpoints of coronal structures. Such an energy deposition drives thermal non-equilibrium solutions in the hydrodynamic equations in longer loops. This heating scenario was considered and discarded by Klimchuk et al. on the basis of their one-dimensional simulations as incapable of reproducing observational characteristics of loops. In this paper, we use three-dimensional simulations to generate synthetic emission images, from which we select and analyze six loops. The main differences between our model and that of Klimchuk et al. concern (1) dimensionality, (2) resolution, (3) geometrical properties of the loops, (4) heating function, and (5) radiative function. We find evidence, in this small set of simulated loops, that the evolution of the light curves, the variation of temperature along the loops, the density profile, and the absence of small-scale structures are compatible with the characteristics of observed loops. We conclude that quasi-steady footpoint heating that drives thermal non-equilibrium solutions cannot yet be ruled out as a viable heating scenario for EUV loops.

Lionello, Roberto; Linker, Jon A.; Mikic, Zoran [Predictive Science, Inc., 9990 Mesa Rim Rd., Ste. 170, San Diego, CA 92121-2910 (United States); Winebarger, Amy R. [NASA Marshall Space Flight Center, ZP 13, Huntsville, AL 35812 (United States); Mok, Yung, E-mail: lionel@predsci.com, E-mail: linkerj@predsci.com, E-mail: mikicz@predsci.com, E-mail: amy.r.winebarger@nasa.gov, E-mail: ymok@uci.edu [Department of Physics and Astronomy, University of California, 4129 Reines Hall, Irvine, CA 92697 (United States)

2013-08-20T23:59:59.000Z

414

Influence of Hydraulics and Control of Thermal Storage in Solar Assisted Heat Pump Combisystems  

Science Journals Connector (OSTI)

Abstract This paper studies the influence of hydraulics and control of thermal storage in systems combined with solar thermal and heat pump for the production of warm water and space heating in dwellings. A reference air source heat pump system with flat plate collectors connected to a combistore was defined and modeled together with the IEA SHC Task 44/HPP Annex 38 (T44A38) “Solar and Heat Pump Systems” boundary conditions of Strasbourg climate and SFH45 building. Three and four pipe connections as well as use of internal and external heat exchangers for DHW preparation were investigated as well as sensor height for charging of the DHW zone in the store. The temperature in this zone was varied to ensure the same DHW comfort was achieved in all cases. The results show that the four pipe connection results in 9% improvement in SPF compared to three pipe and that the external heat exchanger for DHW preparation leads to a 2% improvement compared to the reference case. Additionally the sensor height for charging the DHW zone of the store should not be too low, otherwise system performance is adversely affected.

Stefano Poppi; Chris Bales

2014-01-01T23:59:59.000Z

415

Review of Helium and Xenon Pure Component and Mixture Transport Properties and Recommendation of Estimating Approach for Project Prometheus (Viscosity and Thermal Conductivity)  

SciTech Connect

The selected configuration for the Project Prometheus Space Nuclear Power Plant was a direct coupling of Brayton energy conversion loop(s) to a single reactor heat source through the gas coolant/working fluid. A mixture of helium (He) and xenon (Xe) gas was assumed as the coolant/working fluid. Helium has superior thermal conductivity while xenon is added to increase the gas atomic weight to benefit turbomachinery design. Both elements have the advantage of being non-reactive. HeXe transport properties (viscosity and thermal conductivity) were needed to calculate pressure drops and heat transfer rates. HeXe mixture data are limited, necessitating the use of semi-empirical correlations to calculate mixture properties. Several approaches are available. Pure component properties are generally required in the mixture calculations. While analytical methods are available to estimate pure component properties, adequate helium and xenon pure component data are available. This paper compares the sources of pure component data and the approaches to calculate mixture properties. Calculated mixture properties are compared to the limited mixture data and approaches are recommended to calculate both pure component and mixture properties. Given the limited quantity of HeXe mixture data (all at one atmosphere), additional testing may have been required for Project Prometheus to augment the existing data and confirm the selection of mixture property calculation methods.

Haire, Melissa A.; Vargo, David D. [Bechtel Bettis, Inc., Bettis Atomic Power Laboratory, P.O. Box 79, West Mifflin, PA 15122 (United States)

2007-01-30T23:59:59.000Z

416

Numerical Modeling of the Transient Thermal Interference of Vertical U-Tube Haet Exchangers  

E-Print Network (OSTI)

installation separation range. Non-homogenous media were modeled by varying backfill thermal conductivity. Maximum heat transfer was achieved with a fictitious backfill thermal conductivity of 1,000 W/m-K, while measured bentonite backfill conductivities were...

Muraya, Norman K.

417

Heat flow determinations and implied thermal regime of the Coso geothermal  

Open Energy Info (EERE)

determinations and implied thermal regime of the Coso geothermal determinations and implied thermal regime of the Coso geothermal area, California Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: Heat flow determinations and implied thermal regime of the Coso geothermal area, California Details Activities (1) Areas (1) Regions (0) Abstract: Obvious surface manifestations of an anomalous concentration of geothermal energy at the Coso Geothermal Area, California, include fumarolic activity, active hot springs, and associated hydrothermally altered rocks. Abundant Pleistocene volcanic rocks, including a cluster of thirty-seven rhyolite domes, occupy a north-trending structural and topographic ridge near the center of an oval-shaped zone of late Cenozoic ring faulting. In an investigation of the thermal regime of the geothermal

418

Pressurized heat treatment of glass-ceramic to control thermal expansion  

DOE Patents (OSTI)

A method of producing a glass-ceramic having a specified thermal expansion value is disclosed. The method includes the step of pressurizing the parent glass material to a predetermined pressure during heat treatment so that the glass-ceramic produced has a specified thermal expansion value. Preferably, the glass-ceramic material is isostatically pressed. A method for forming a strong glass-ceramic to metal seal is also disclosed in which the glass-ceramic is fabricated to have a thermal expansion value equal to that of the metal. The determination of the thermal expansion value of a parent glass material placed in a high-temperature environment is also used to determine the pressure in the environment.

Kramer, Daniel P. (Dayton, OH)

1985-01-01T23:59:59.000Z

419

LATERAL HEAT FLOW INFRARED THERMOGRAPHY FOR THICKNESS INDEPENDENT DETERMINATION OF THERMAL DIFFUSIVITY IN CFRP  

SciTech Connect

In conventional infrared thermography, determination of thermal diffusivity requires thickness information. Recently GE has been experimenting with the use of lateral heat flow to determine thermal diffusivity without thickness information. This work builds on previous work at NASA Langley and Wayne State University but we incorporate thermal time of flight (tof) analysis rather than curve fitting to obtain quantitative information. We have developed appropriate theoretical models and a tof based data analysis framework to experimentally determine all components of thermal diffusivity from the time-temperature measurements. Initial validation was carried out using finite difference simulations. Experimental validation was done using anisotropic carbon fiber reinforced polymer (CFRP) composites. We found that in the CFRP samples used, the in-plane component of diffusivity is about eight times larger than the through-thickness component.

Tralshawala, Nilesh; Howard, Don; Knight, Bryon; Plotnikov, Yuri; Ringermacher, Harry [Nondestructive Technologies Laboratory, GE--Global Research Center, Niskayuna, NY 12309 (United States)

2008-02-28T23:59:59.000Z

420

Survey and evaluation of available thermal insulation materials for use on solar heating and cooling systems  

SciTech Connect

This is the final report of a survey and evaluation of insulation materials for use with components of solar heating and cooling systems. The survey was performed by mailing questionnaires to manufacturers of insulation materials and by conducting an extensive literature search to obtain data on relevant properties of various types of insulation materials. The study evaluated insulation materials for active and passive solar heating and cooling systems and for multifunction applications. Primary and secondary considerations for selecting insulation materials for various components of solar heating and cooling systems are presented.

Not Available

1980-03-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


421

An improved absorption generator for solar-thermal powered heat pumps. Part 1: Feasibility  

SciTech Connect

Solar heated absorption chiller installations have been, typically, very expensive for their rating. The need to keep the liquid flowing within the collectors as cool as possible to enhance collector thermal efficiency, conflicts with the need to operate the absorption chiller at a higher temperature. The compromise usually results in poor collector efficiency as well as a relatively poor specific chiller effect. The proposed vortex generator permits a heat pump to operate efficiently with relatively low temperature solar heated fluid (70--80 C). As a result, the collectors are cooler and much more efficient. In addition, the specific heat pumping capacity is about 27% greater than conventional systems operating at the same reduced generator temperatures and, therefore, a smaller chiller is required. The economic consequences of these benefits will be presented in Part 2.

Fineblum, S. [Megadyne Inc., Rochester, NY (United States)

1997-12-31T23:59:59.000Z

422

An improved absorption generator for solar-thermal powered heat pumps. Part 2: Energy and economics  

SciTech Connect

Solar heated absorption chiller installations have been very expensive for their rating. To enhance collector thermal efficiency the liquid flowing within the collectors must be kept as cool as possible. However, there is also a need to operate the absorption reported earlier. The compromise usually results in poor collector efficiency as well as a relatively poor specific chiller effect. The proposed vortex generator permits a heat pump to operate efficiently with relatively low temperature solar heated fluid (70--80 C). As a result, the collectors are cooler and more efficient. As noted in Part 1, the specific heat pumping capacity is about 27% greater than conventional systems operating at the same reduced generator temperatures. Therefore, a smaller, less expensive chiller is required. The reduced investment in solar arrays and absorption chillers is estimated along with a range of paybacks.

Fineblum, S. [Megadyne Inc., Rochester, NY (United States)

1997-12-31T23:59:59.000Z

423

Feasibility of combined solar thermal and ground source heat pump systems in cold climate, Canada  

Science Journals Connector (OSTI)

This document presents a study for examining the viability of hybrid ground source heat pump (GSHP) systems that use solar thermal collectors as the supplemental component in heating dominated buildings. Loads for an actual house in the City of Milton near Toronto, Canada, were estimated. TRNSYS, a system simulation software tool, was used to model yearly performance of a conventional GSHP system as well as a proposed hybrid GSHP system. Actual yearly data collected from the site were examined against the simulation results. This study demonstrates that hybrid ground source heat pump system combined with solar thermal collectors is a feasible choice for space conditioning for heating dominated houses. It was shown that the solar thermal energy storage in the ground could reduce a large amount of ground heat exchanger (GHX) length. Combining three solar thermal collectors with a total area of 6.81 m2 to a GSHP system will reduce GHX length by 15%. Sensitivity analysis was carried out for different cities of Canada and resulted that Vancouver, with mildest climate compared to other cities, was the best candidate for the proposed solar hybrid GSHP system with a GHX length reduction to solar collector area ratio of 7.64 m/m2. Overall system economic viability was also evaluated using a 20-year life-cycle cost analysis. The analysis showed that there is small economic benefit in comparing to the conventional GSHP system. The net present value of the proposed hybrid system based on the 20-year life-cycle cost analysis was estimated to be in a range of 3.7%–7.6% (or $1500 to $3430 Canadian dollar) lower than the conventional GSHP system depending on the drilling cost.

Farzin M. Rad; Alan S. Fung; Wey H. Leong

2013-01-01T23:59:59.000Z

424

Heat transfer deterioration in tubes caused by bulk flow acceleration due to thermal and frictional influences  

SciTech Connect

Severe deterioration of forced convection heat transfer can be encountered with compressible fluids flowing through strongly heated tubes of relatively small bore as the flow accelerates and turbulence is reduced because of the fluid density falling (as the temperature rises and the pressure falls due to thermal and frictional influence). The model presented here throws new light on how the dependence of density on both temperature and pressure can affect turbulence and heat transfer and it explains why the empirical equations currently available for calculating effectiveness of forced convection heat transfer under conditions of strong non-uniformity of fluid properties sometimes fail to reproduce observed behaviour. It provides a criterion for establishing the conditions under which such deterioration of heat transfer might be encountered and enables heat transfer coefficients to be determined when such deterioration occurs. The analysis presented here is for a gaseous fluid at normal pressure subjected strong non-uniformity of fluid properties by the application of large temperature differences. Thus the model leads to equations which describe deterioration of heat transfer in terms of familiar parameters such as Mach number, Reynolds number and Prandtl number. It is applicable to thermal power plant systems such as rocket engines, gas turbines and high temperature gas-cooled nuclear reactors. However, the ideas involved apply equally well to fluids at supercritical pressure. Impairment of heat transfer under such conditions has become a matter of growing interest with the active consideration now being given to advanced water-cooled nuclear reactors designed to operate at pressures above the critical value. (authors)

Jackson, J. D. [Univ. of Manchester, Manchester (United Kingdom)

2012-07-01T23:59:59.000Z

425

Thermal emission of neutron stars with internal heaters  

Science Journals Connector (OSTI)

......our consideration of thermal coupling/decoupling...dependence of redshifted thermal heat-conduction flux...star (in units of solar luminosity Lo) for...sufficiently long time to overheat the crust and violate the thermal balance of the crust......

A. D. Kaminker; A. A. Kaurov; A. Y. Potekhin; D. G. Yakovlev

2014-01-01T23:59:59.000Z

426

Two-Dimensional Computational Fluid Dynamics and Conduction Simulations of Heat Transfer in Horizontal Window Frames with Internal Cavities  

SciTech Connect

This paper assesses the accuracy of the simplified frame cavity conduction/convection and radiation models presented in ISO 15099 and used in software for rating and labeling window products. Temperatures and U-factors for typical horizontal window frames with internal cavities are compared; results from Computational Fluid Dynamics (CFD) simulations with detailed radiation modeling are used as a reference. Four different frames were studied. Two were made of polyvinyl chloride (PVC) and two of aluminum. For each frame, six different simulations were performed, two with a CFD code and four with a building-component thermal-simulation tool using the Finite Element Method (FEM). This FEM tool addresses convection using correlations from ISO 15099; it addressed radiation with either correlations from ISO 15099 or with a detailed, view-factor-based radiation model. Calculations were performed using the CFD code with and without fluid flow in the window frame cavities; the calculations without fluid flow were performed to verify that the CFD code and the building-component thermal-simulation tool produced consistent results. With the FEM-code, the practice of subdividing small frame cavities was examined, in some cases not subdividing, in some cases subdividing cavities with interconnections smaller than five millimeters (mm) (ISO 15099) and in some cases subdividing cavities with interconnections smaller than seven mm (a breakpoint that has been suggested in other studies). For the various frames, the calculated U-factors were found to be quite comparable (the maximum difference between the reference CFD simulation and the other simulations was found to be 13.2 percent). A maximum difference of 8.5 percent was found between the CFD simulation and the FEM simulation using ISO 15099 procedures. The ISO 15099 correlation works best for frames with high U-factors. For more efficient frames, the relative differences among various simulations are larger. Temperature was also compared, at selected locations on the frames. Small differences was found in the results from model to model. Finally, the effectiveness of the ISO cavity radiation algorithms was examined by comparing results from these algorithms to detailed radiation calculations (from both programs). Our results suggest that improvements in cavity heat transfer calculations can be obtained by using detailed radiation modeling (i.e. view-factor or ray-tracing models), and that incorporation of these strategies may be more important for improving the accuracy of results than the use of CFD modeling for horizontal cavities.

Gustavsen, Arlid; Kohler, Christian; Dalehaug, Arvid; Arasteh, Dariush

2008-12-01T23:59:59.000Z

427

1D-to-3D transition of photon heat conduction in polyethylene using molecular dynamics simulations  

E-Print Network (OSTI)

Experiments have demonstrated that the mechanical stretching of bulk polyethylene can increase its thermal conductivity by more than two orders of magnitude, from 0.35 W/mK to over 40W/mK, which is comparable to steel. ...

Henry, Asegun Sekou Famake

2009-01-01T23:59:59.000Z

428

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

E-Print Network (OSTI)

537°C) steam for the steam turbine to generate electricity.as heat sources for steam turbines. Mainly three approachesto Stirling or Brayton steam turbine, moderate to high heat

Roshandell, Melina

2013-01-01T23:59:59.000Z

429

Study on Performance Verification and Evaluation of District Heating and Cooling System Using Thermal Energy of River Water  

E-Print Network (OSTI)

September 16, 2014 NIKKEN SEKKEI Research Institute Naoki Takahashi Study on Performance Verification and Evaluation of District Heating and Cooling System Using Thermal Energy of River Water ESL-IC-14-09-19 Proceedings of the 14th International... of the 14th International Conference for Enhanced Building Operations, Beijing, China, September 14-17, 2014 District heating and cooling system in Nakanoshima 4 Characteristics of heat supply plant in Nakanoshima district -River water is utilized as heat...

Takahashi,N.; Niwa, H.; Kawano,M.; Koike,K.; Koga,O.; Ichitani, K.; Mishima,N.

2014-01-01T23:59:59.000Z

430

Use of impure inert gases in the controlled heating and cooling of mixed conducting metal oxide materials  

DOE Patents (OSTI)

Method for processing an article comprising mixed conducting metal oxide material. The method comprises contacting the article with an oxygen-containing gas and either reducing the temperature of the oxygen-containing gas during a cooling period or increasing the temperature of the oxygen-containing gas during a heating period; during the cooling period, reducing the oxygen activity in the oxygen-containing gas during at least a portion of the cooling period and increasing the rate at which the temperature of the oxygen-containing gas is reduced during at least a portion of the cooling period; and during the heating period, increasing the oxygen activity in the oxygen-containing gas during at least a portion of the heating period and decreasing the rate at which the temperature of the oxygen-containing gas is increased during at least a portion of the heating period.

Carolan, Michael Francis (Allentown, PA); Bernhart, John Charles (Fleetwood, PA)

2012-08-21T23:59:59.000Z

431

Microstructural characterization and microstructural effects on the thermal conductivity of AlN(Y2O3) ceramics  

E-Print Network (OSTI)

Microstructural characterization and microstructural effects on the thermal conductivity of AlN(Y2O3) ceramics Ying-Da Yu a , Aase Marie Hundere b , Ragnvald Høier a , Rafal E. Dunin-Borkowski c aluminum nitride (AlN) ceramic materials with Y2O3 as a sintering additive have been sintered at 1880 C

Dunin-Borkowski, Rafal E.

432

E. In Situ Polymerization of Cyclic Butylene Terephthalate(CBT) Oligomers with Conductive fillers for Thermal Management  

E-Print Network (OSTI)

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

Harmon, Julie P.

433

Analysis of conductive and convective heat transfer in a sedimentary basin, demonstrated for the Rheingraben  

Science Journals Connector (OSTI)

......by 50 per cent and at individual sites by as much as 120 per cent. energy...interpretation of thermal data from the Nevada test site, Open-File Report 82-973...interpretation of thermal data from the Nevada test site, Open-File Report 82-973......

C. Clauser; H. Villinger

1990-03-01T23:59:59.000Z

434

Temperature and thermal stress distributions for the HFIR permanent reflector generated by nuclear heating  

SciTech Connect

The beryllium permanent reflector of the High Flux Isotope Reactor has the main functions for slowing down and reflecting the neutrons and housing the experimental facilities. The reflector is heated as a result of the nuclear reaction. Heat is removed mainly by the cooling water passing through the densely distributed coolant holes along the vertical or axial direction of the reflector. The reflector neutronic distribution and its heating rate are calculated by J.C. Gehin of the Oak Ridge National Laboratory by applying the Monte Carlo Code MCNP. The heat transfer boundary conditions along several reflector interfaces are estimated to remove additional heat from the reflector. The present paper is to report the calculation results of the temperature and the thermal stress distributions of the permanent reflector by applying the computer aided design code I-DEAS and the finite element code ABAQUS. The present calculation is to estimate the high stress areas as a result of the new beam tube cutouts along the horizontal mid-plane of the reflector of the recent reactor upgrade project. These high stresses were not able to be calculated in the preliminary design analysis in earlier 60`s. The heat transfer boundary conditions are used in this redesigned calculation. The material constants and the acceptance criteria for the allowable stresses are mainly based on that assumed in the preliminary design report.

Chang, S.J.

1998-04-01T23:59:59.000Z

435

Fundamental heat transfer processes related to phase change thermal storage media  

SciTech Connect

Research on fundamental heat transfer processes which occur in phase-change thermal storage systems is described. The research encompasses both melting and freezing, and includes both experiment and analysis. The status of four research problems is discussed. One of the freezing problems was focused on investigating, via experiment, the extent to which freezing can be enhanced by the attachment of fins to the external surface of a cooled vertical tube situated in a liquid phase-change medium. Very substantial enhancements were encountered which neutralize the degradation of freezing due to the thermal resistance of the frozen layer and to natural convection in the liquid phase. The second of the freezing problems was analytical in nature and sought to obtain solutions involving both the phase-change medium and the heat transfer fluid used either to add heat to or extract heat from the medium. For freezing on a plane wall, it was possible to obtain a closed-form analytical solution, while for freezing about a coolant-carrying circular tube, a new numerical methodology was devised to obtain finite-difference solutions. For melting, quantitative design-quality heat transfer coefficients were determined experimentally for melting adjacent to a heated vertical tube. These experiments explored the effects of solid-phase subcooling and of open versus closed top containment on the coefficients. A dimensionless correlation enables these results to be used for a wide range of phase-change media. Studies on melting of a phase-change material situated within a circular tube are in progress.

Sparrow, E. M.; Ramsey, J. W.

1981-01-01T23:59:59.000Z

436

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

E-Print Network (OSTI)

Thermal energy storage for sustainable energy consumption –Sustainable Energy, Cambridge University Press, 65- Dermott A.M, Frysinger G.R, Storage

Roshandell, Melina

2013-01-01T23:59:59.000Z

437

PUBLISHED ONLINE: 9 MAY 2010 | DOI: 10.1038/NMAT2753 Dimensional crossover of thermal transport in  

E-Print Network (OSTI)

on heat conduction in low-dimensional materials and may open up FLG applications in thermal management , is heat conduction in low- dimensional materials. The question of what happens with thermal conductivity unique electronic2,3 and optical properties4 , reveals unusually high thermal conductivity5,6 . The fact

438

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

E-Print Network (OSTI)

been heated at solar collection tower, at the temperatureIn the receiver tower, the collected solar radiation heatsfocus and send solar radiation to a receiver tower.

Roshandell, Melina

2013-01-01T23:59:59.000Z

439

Turbulent heat transfer characteristics in a circular tube and thermal properties of n-decane-in-water nanoemulsion fluids and micelles-in-water fluids  

Science Journals Connector (OSTI)

Abstract We carry out experimental studies of turbulent convective heat transfer of several n-decane-in-water nanoemulsions and micelles-in-water fluids. We characterize the viscosity and thermal properties of the nanofluids, and the nanoparticle distributions and shapes with various techniques, including transmission electron microscopy. We find that the thermal conductivity of the nanofluids is lower than that of the base fluid, and the conductivity shows no anomalous behavior. Despite this we find that the average Nusselt numbers and convective heat transfer coefficients are enhanced for low volume fractions when the Reynolds number Re > 7000, in agreement with solid particle nanofluids. However, when the pressure losses are taken into account, we find that the nanofluids studied have a practical efficiency equal to or less than that of the base fluid. The highest heat transfer enhancements were obtained with volume fractions considerably smaller than those for the solid particle nanofluids. Our results indicate that the improved heat transfer is due to enhancement of turbulence in the large Re regime.

Sampo Saarinen; Salla Puupponen; Arttu Meriläinen; Aliakbar Joneidi; Ari Seppälä; Kari Saari; Tapio Ala-Nissila

2015-01-01T23:59:59.000Z

440

An experimental and theoretical study of radiative and conductive heat transfer in nongray semitransparent media  

E-Print Network (OSTI)

One dimensional temperature profiles and heat fluxes within a slab of molten glass were measured experimentally. The glass slab was contained in a platinum foil lined ceramic tray inside a high temperature furnace. An ...

Eryou, N. Dennis

1969-01-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


441

Some aspects of the computer simulation of conduction heat transfer and phase change processes  

SciTech Connect

Various aspects of phase change processes in materials are discussd including computer modeling, validation of results and sensitivity. In addition, the possible incorporation of cognitive activities in computational heat transfer is examined.

Solomon, A. D.

1982-04-01T23:59:59.000Z

442

Microstructure changes and thermal conductivity reduction in UO2 following 3.9 MeV He2+ ion irradiation  

SciTech Connect

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.

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

443

Monitoring and simulation of the thermal performance of solar heated outdoor swimming pools  

SciTech Connect

Based on detailed measurements of two outdoor swimming pools (at Leonberg and Moehringen) a computer model has been developed and validated for the simulation of the thermal behaviour of such pools. The subroutine is compatible to TRNSYS 13.1. Correlations for the heat losses due to evaporation, convection, and radiation were taken from literature and tested in the model. It was not possible to select one optimal correlation for the description of the evaporative heat losses of both swimming pools due to the different exposure to wind. Using the most suitable correlation for the evaporative heat losses of each pool allowed for the simulation of the pool temperature with less than 0.5 K standard deviation between measured and simulated temperature. the major problem was the measurement of the relevant wind speed to be used in the correlations describing the evaporative heat losses under real outdoor conditions. A method is described detailing how to calibrate the model using the heating energy requirement and the measured pool temperature during actual operation periods. The analysis of the measured data of two different outdoor swimming pools under the same climatic conditions showed differences of a factor 2 and more in the heat demand per unit pool area. This was mainly caused by the difference in local wind speed which differed by more than a factor 4. The two pools investigated were heated by solar energy with a fraction of 28% and 14%, respectively, and the seasonal efficiency of the solar systems was 37.7% and 33.4%. Simulations show that a reduction of the water temperature from 24[degrees]C to 22[degrees]C during periods with low outdoor temperatures and few visitors, reduces the fuel consumption to less than half and increases the solar fraction from 28% to 50% in one pool.

Hahne, E.; Kuebler, R. (Universitaet Stuttgart (Germany))

1994-07-01T23:59:59.000Z

444

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

E-Print Network (OSTI)

opto-electronics, plasmonics, and ultra-sensitive bolometry. Here we present measurements of bipolar con- ductance over a temperature range of 300 mK to 100 K, using three different sample configurations of 10-20 J/K at 300 mK, which is 9 times smaller than the previous record[15]. For higher temperatures

445

Thermal insulation constructal optimization for steel rolling reheating furnace wall based on entransy dissipation extremum principle  

Science Journals Connector (OSTI)

Analogizing with the heat conduction process, the entransy dissipation extremum principle for thermal insulation process can be described as: for a ... heat loss) with certain constraints, the thermal insulation ...

HuiJun Feng; LinGen Chen; ZhiHui Xie; FengRui Sun

2012-12-01T23:59:59.000Z

446

A comparison of two heat transfer models for estimating thermal drawdown in Hot Dry Rock reservoirs  

SciTech Connect

Estimates of thermal drawdown in Hot Dry Rock geothermal systems have been made with two different models of heat transfer from hydraulically fractured reservoir rock blocks to water circulated through the fracture permeability. One model is based on deconvolution of experimental tracer response curves into a network of flowpaths connected in parallel with heat transfer calculated individually in each flowpath. The second model is based on one-dimensional flow through the rock with a block size distribution described as a group of equivalent-radius spheres for which the heat transfer equations can be solved analytically. The two models were applied to the planned Phase II long-term thermal drawdown experiment at Fenton Hill, NM. The results show good agreement between the two models, with estimates of temperature cooldown from 240ºC to 150ºC in a few years depending on selected operation parameters, but with somewhat differing cooldown curve characteristic shapes. Data from the long-term experiment will be helpful in improving the two models.

Robinson, Bruce A.; Kruger, Paul

1988-01-01T23:59:59.000Z

447

Economic analysis of community solar heating systems that use annual cycle thermal energy storage  

SciTech Connect

The economics of community-scale solar systems that incorporate a centralized annual cycle thermal energy storage (ACTES) coupled to a distribution system is examined. Systems were sized for three housing configurations: single-unit dwellings, 10-unit, and 200-unit apartment complexes in 50-, 200-, 400-, and 1000-unit communities in 10 geographic locations in the United States. Thermal energy is stored in large, constructed, underground tanks. Costs were assigned to each component of every system in order to allow calculation of total costs. Results are presented as normalized system costs per unit of heat delivered per building unit. These methods allow: (1) identification of the relative importance of each system component in the overall cost; and (2) identification of the key variables that determine the optimum sizing of a district solar heating system. In more northerly locations, collectors are a larger component of cost. In southern locations, distribution networks are a larger proportion of total cost. Larger, more compact buildings are, in general, less expensive to heat. For the two smaller-scale building configurations, a broad minima in total costs versus system size is often observed.

Baylin, F.; Monte, R.; Sillman, S.; Hooper, F.C.; McClenahan, J.D.

1981-02-01T23:59:59.000Z

448

Solving transient conduction and radiation heat transfer problems using the lattice Boltzmann method and the finite volume method  

SciTech Connect

The lattice Boltzmann method (LBM) was used to solve the energy equation of a transient conduction-radiation heat transfer problem. The finite volume method (FVM) was used to compute the radiative information. To study the compatibility of the LBM for the energy equation and the FVM for the radiative transfer equation, transient conduction and radiation heat transfer problems in 1-D planar and 2-D rectangular geometries were considered. In order to establish the suitability of the LBM, the energy equations of the two problems were also solved using the FVM of the computational fluid dynamics. The FVM used in the radiative heat transfer was employed to compute the radiative information required for the solution of the energy equation using the LBM or the FVM (of the CFD). To study the compatibility and suitability of the LBM for the solution of energy equation and the FVM for the radiative information, results were analyzed for the effects of various parameters such as the scattering albedo, the conduction-radiation parameter and the boundary emissivity. The results of the LBM-FVM combination were found to be in excellent agreement with the FVM-FVM combination. The number of iterations and CPU times in both the combinations were found comparable.

Mishra, Subhash C. [Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati 781039 (India)]. E-mail: scm_iitg@yahoo.com; Roy, Hillol K. [Department of Mechanical Engineering, Indian Institute of Technology Guwahati, Guwahati 781039 (India)

2007-04-10T23:59:59.000Z

449

Thermal conductivity of anisotropic spin-1/2 two leg ladder: Green’s function approach  

Science Journals Connector (OSTI)

We study the thermal transport of a spin-1/2 two leg antiferromagnetic ladder in the direction of legs. The possible effect of spin-orbit coupling and crystalline electric field are investigated in terms of aniso...

Hamed Rezania; Abdollah Langari…

2014-08-01T23:59:59.000Z

450

Thermal Conductivity Reduction and Thermoelectric Figure of Merit Increase by Embedding Nanoparticles in Crystalline Semiconductors  

E-Print Network (OSTI)

, 63.22.+m, 65.80.+n, 66.60.+a The performance of thermoelectric energy conversion devices depends to achieve high carrier mobility. The lowest thermal conduc- tivity in crystalline solids is generally

451

AN EXPERIMENTAL AND THEORETICAL STUDY OF HEAT TRANSFER WITH COMBUSTION  

E-Print Network (OSTI)

specific heat of ceramic thermal conductivity of ceramic kwthermal penetration depth is much smaller than the characterlstic dimensions of the gauge. The ceramic

Heperkan, Hasan A.

2013-01-01T23:59:59.000Z

452

Fluid Circulation and Heat Extraction from Engineered Geothermal...  

Open Energy Info (EERE)

from Engineered Geothermal Reservoirs Abstract A large amount of fluid circulation and heat extraction (i.e., thermal power production) research and testing has been conducted...

453

Thermal cycling effect on the nanoparticle distribution and specific heat of a carbonate eutectic with alumina nanoparticles  

E-Print Network (OSTI)

. The concentration of alumina nanoparticles in this material was measured using neutron activation analysis. The average specific heat of the uncycled material was found to be 1.37 J/g°C.The average specific heat of the thermally cycled material was between 1.7-2.1 J...

Shankar, Sandhya

2011-08-08T23:59:59.000Z

454

HeatProbe: a Thermal-based Power Meter System for Tracking Per-user Power Consumption  

E-Print Network (OSTI)

HeatProbe: a Thermal-based Power Meter System for Tracking Per-user Power Consumption Nan-Chen Chen Technology Innovation, Academic Sinica2 {b97006, b96118, b95701241}@csie.ntu.edu.tw, cwyou@citi.sinica.edu.tw, hchu@csie.ntu.edu.tw, mschen@citi.sinica.edu.tw Abstract. This paper proposes HeatProbe, a per

Chu, Hao-hua

455

Using neural networks to predict thermal conductivity from geophysical well logs  

Science Journals Connector (OSTI)

......mineralogic indicator), shear wave velocity (an energy transport property) and spontaneous potential...259-564. Della Vedova B. , Von Herzen R., 1987. Geothermal heat flux at the COST B-2 and B-3 wells, US Atlantic continental......

Bruno Goutorbe; Francis Lucazeau; Alain Bonneville

2006-07-01T23:59:59.000Z

456

Heat transfer and fluid flow in microchannels and nanochannels at high Knudsen number using thermal lattice-Boltzmann method  

Science Journals Connector (OSTI)

The present paper deals with the two-dimensional numerical simulation of gaseous flow and heat transfer in planar microchannel and nanochannel with different wall temperatures in transitional regime 0.1?Kn?1. An atomistic molecular simulation method is used known as thermal lattice-Boltzmann method. The results of simulation are presented in four cases corresponding to the Fourier flow, shear-driven flow (Couette flow), pressure-driven flow (Poiseuille flow), and mixed shear–pressure-driven flow in the developing and fully developed regions. The mixed shear–pressure-driven flow is divided into two subcases with shear stress and pressure gradient acting in the same and the opposite directions. Normalized temperature and velocity profiles across the channel, distribution of local wall Nusselt number, and friction coefficient are illustrated. Using this method, nonlinear pressure distribution in the streamwise direction, reduction in mass flow rate, Cf?Re, and Nu by increasing the Knudsen number are studied. It is seen that for Couette flow, Nu over the hotter plate is greater than the cooler plate, but for the pressure-driven flow with stationary wall temperature dependency of viscosity and thermal conductivity causes this trend to be reversed. The reversed flow appearance in the velocity profile is captured in the case of opposite shear–pressure-driven flow.

J. Ghazanfarian and A. Abbassi

2010-08-13T23:59:59.000Z

457

A Second Order Thermal and Momentum Immersed Boundary Method for Conjugate Heat Transfer in a Cartesian Finite Volume Solver  

E-Print Network (OSTI)

A conjugate heat transfer (CHT) immersed boundary (IB and CHTIB) method is developed for use with laminar and turbulent flows with low to moderate Reynolds numbers. The method is validated with the canonical flow of two co-annular rotating cylinders at $Re=50$ which shows second order accuracy of the $L_{2}$ and $L_{\\infty}$ error norms of the temperature field over a wide rage of solid to fluid thermal conductivities, $\\kappa_{s}/\\kappa_{f} = \\left(9-100\\right)$. To evaluate the CHTIBM with turbulent flow a fully developed, heated, turbulent channel $\\left(Re_{u_{\\tau}}=150\\text{ and } \\kappa_{s}/\\kappa_{f}=4 \\right)$ is used which shows near perfect correlation to previous direct numerical simulation (DNS) results. The CHTIB method is paired with a momentum IB method (IBM), both of which use a level set field to define the wetted boundaries of the fluid/solid interfaces and are applied to the flow solver implicitly with rescaling of the difference operators of the finite volume (FV) method (FVM).

Crocker, Ryan; Desjardins, Olivier

2014-01-01T23:59:59.000Z

458

RELAP5/MOD3 simulation of the loss of residual heat removal during midloop operation experiment conducted at the ROSA-IV/ Large Scale Test Facility  

E-Print Network (OSTI)

The modeling of the complex thermal hydraulics Of reactor systems involves the use Of experimental test systems as well as numerical codes. A simulation of the loss of residual heat removal (RHR) during midloop operations was performed using...

Banerjee, Sibashis Sanatkumar

2012-06-07T23:59:59.000Z

459

An experimental study of endwall heat transfer enhancement for flow past staggered non-conducting pin fin arrays  

E-Print Network (OSTI)

: : : : : : : : : : : : : : : : : : : : : : : : 15 VI RESULTS AND DISCUSSION : : : : : : : : : : : : : : : : : : : 17 A. Effect of Reynolds Number ReDh . . . . . . . . . . . . . . 17 B. Effect of Height of Pins, H=D . . . . . . . . . . . . . . . . 21 C. Effect of Stream Wise Spacing of Pins, SL=D... Pressure Drop for D = 2:54cm : 23 9 Effect of H=D on Thermal Performance for D = 2:54cm : : : : : : : 24 10 Effect of SL=D on Heat Transfer Enhancement for D=1.27cm : : : : 25 11 Effect of SL=D on Increase of Overall Pressure Drop for D = 1:27cm 26 12...

Achanta, Vamsee Satish

2004-09-30T23:59:59.000Z

460

Thermoeconomic optimization of sensible heat thermal storage for cogenerated waste-to-energy recovery  

SciTech Connect

This paper investigates the feasibility of employing thermal storage for cogenerated waste-to-energy recovery such as using mass-burning water-wall incinerators and topping steam turbines. Sensible thermal storage is considered in rectangular cross-sectioned channels through which is passed unused process steam at 1,307 kPa/250 C (175 psig/482 F) during the storage period and feedwater at 1,307 kPa/102 C (175 psig/216 F) during the recovery period. In determining the optimum storage configuration, it is found that the economic feasibility is a function of mass and specific heat of the material and surface area of the channel as well as cost of material and fabrication. Economic considerations included typical cash flows of capital charges, energy revenues, operation and maintenance, and income taxes. Cast concrete is determined to be a potentially attractive storage medium.

Abdul-Razzak, H.A. [Texas A and M Univ., Kingsville, TX (United States). Dept. of Mechanical and Industrial Engineering; Porter, R.W. [Illinois Inst. of Tech., chicago, IL (United States). Dept. of Mechanical and Aerospace Engineering

1995-10-01T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
While these samples are representative of the content of NLEBeta,
they are not comprehensive nor are they the most current set.
We encourage you to perform a real-time search of NLEBeta
to obtain the most current and comprehensive results.


461

Heat Sweep Analysis of Thermal Breakthrough at Los Humeros and La Primavera Fields, Mexico  

SciTech Connect

Early evaluation of the potential for geothermal breakthrough of reinjected fluids in newly developed geothermal fields can be obtained with the SGP one-dimensional heat sweep model. The model was used to estimate fluid cooldown from wells selected for the first wellhead generating units to be installed at the Los Humeros and La Primavera geothermal fields in Mexico, based on staff-compiled geometric and geologic data, thermal properties of the reservoir rock, and expected production conditions. Geometric considerations were evaluated with respect to known and postulated fault zones and return flow angle of the reinjected fluid. The results show the range of parameter values that affect the rate of thermal breakthrough to an abandonment temperature of 170 ºC corresponding to the minimum inlet pressure to the CFE 5-MW wellhead generator units. 9 figs., 4 tabs., 11 refs.

Kruger, P.; Lam, S.; Molinar, R.; Aragon, A.

1987-01-20T23:59:59.000Z

462

Casimir-Lifshitz force out of thermal equilibrium and heat transfer between arbitrary bodies  

E-Print Network (OSTI)

We study the Casimir-Lifshitz force and the radiative heat transfer occurring between two arbitrary bodies, each one held at a given temperature, surrounded by environmental radiation at a third temperature. The system, in stationary configuration out of thermal equilibrium, is characterized by a force and a heat transfer depending on the three temperatures, and explicitly expressed in terms of the scattering operators of each body. We find a closed-form analytic expression valid for bodies of any geometry and dielectric properties. As an example, the force between two parallel slabs of finite thickness is calculated, showing the importance of the environmental temperature as well as the occurrence of a repulsive interaction. An analytic expression is also provided for the force acting on an atom in front of a slab. Our predictions can be relevant for experimental and technological purposes.

Riccardo Messina; Mauro Antezza

2010-12-23T23:59:59.000Z

463

Thermal shock and fatigue resistance of tungsten materials under transient heat loading  

Science Journals Connector (OSTI)

Abstract Transient heat loading tests were performed on rolled pure tungsten (PW) and lanthanum oxide doped tungsten (WL10) as well as swaged + rolled potassium doped tungsten (W-K) samples using an electron beam. In thermal shock tests, the cracking threshold was 0.44–0.66, 0.17–0.22 and 0.44–0.66 GW/m2 for PW, WL10 and W-K, respectively. The melting threshold was over 1.1 GW/m2 for PW and W-K while 0.66–0.88 GW/m2 for WL10. In thermal fatigue tests, the obvious roughening threshold was over 1000 cycles for PW and WL10 while 1–100 cycles for W-K. The cracking threshold was 100–1000 cycles for PW, 1–100 cycles for WL10 and over 1000 cycles for W-K alloy. WL10 displayed worse thermal and fatigue resistance while W-K exhibited better properties compared with PW, which was attributed to differences in thermal–mechanical properties of the three tungsten alloys, in addition to the size and number density of La2O3 particles and potassium bubbles.

Xiaoxin Zhang; Qingzhi Yan; Shaoting Lang; Min Xia; Xiang Liu; Changchun Ge

2014-01-01T23:59:59.000Z

464

Effect of boundary scattering on the thermal conductivity of TiNiSn-based half-Heusler alloys  

Science Journals Connector (OSTI)

TiNiSn-based half-Heusler alloys have been of significant interest for their potential as thermoelectric materials. They exhibit promising electronic transport properties as revealed through high Seebeck coefficient and moderate electrical resistivity values. The chief disadvantage of these materials is a comparatively high lattice thermal conductivity. Attempts to “tune” the lattice thermal conductivity (?L) in these materials have led to the comparison and analysis of the thermal conductivity of two series of Ti- and Zr-based half-Heusler alloys. In the first series, Ti1?yZryNiSn0.95Sb0.05, a significant reduction in ?L is observed, with the substitution of large concentrations of Zr (y?25%) at Ti site, which is most likely due to mass fluctuation scattering. In the second series, TiNiSn1?xSbx, a nonsystematic increase in ?L is observed, with minute amounts of Sb doping (x?5%) at the Sn site. Extensive microstructural analysis in a TiNiSn1?xSbx series reveals a correlation between ?L and the average grain diameter in these materials, which is in good agreement with theoretical predictions related to phonon boundary scattering. In addition, a comparison of the calculated phonon mean free path in each of the series of compounds shows some insight into the two different phonon scattering mechanisms.

S. Bhattacharya; M. J. Skove; M. Russell; T. M. Tritt; Y. Xia; V. Ponnambalam; S. J. Poon; N. Thadhani

2008-05-30T23:59:59.000Z

465

Research Program - Center for Solar and Thermal Energy Conversion  

NLE Websites -- All DOE Office Websites (Extended Search)

below. Organic and Hybrid Systems for TE Improving Thermoelectric Efficiency via Low Thermal Boundary Conductance Heat dissipation in Atomic-Scale Junctions A General Strategy to...

466

ORNL rod-bundle heat-transfer test data. Volume 6. Thermal-hydraulic test facility experimental data report for test 3. 05. 5B - double-ended cold-leg break simulation  

SciTech Connect

Thermal-Hydraulic Test Facility (THTF) Test 3.05.5B was conducted by members of the ORNL PWR Blowdown Heat Transfer Separate-Effects Program on July 3, 1980. The objective of the program is to investigate heat transfer phenomena believed to occur in PWRs during accidents, including small and large break loss-of-coolant accidents. Test 3.05.5B was designed to provide transient thermal-hydraulics data in rod bundle geometry under reactor accident-type conditions. Reduced instrument responses are presented. Also included are uncertainties in the instrument responses, calculated mass flows, and calculated rod powers.

Mullins, C.B.; Felde, D.K.; Sutton, A.G.; Gould, S.S.; Morris, D.G.; Robinson, J.J.; Schwinkendorf, K.N.

1982-05-18T23:59:59.000Z

467

Effects of axial plate heat conduction on the thermal performance of a laminar counterflow flat plate heat exchanger  

E-Print Network (OSTI)

UC (I ~ M) ?0 e DO VC {I, N) ?O. DO UH(I, l)=0 DO VH (I, 1) ?O. DO ALONG FLUID CENTERLINE DO 6 I?1, N FOR VOBTICITY AMD STREAM WH(I, M) =0 ODO WC (I ~ 'l) =Do ODD PSIC(I ~ 1) =le ODO-RD PSIH fI, N) 1. ODO-BD CENTERLINE VALOIS FOB TH...-VELOCITY HOT' CALL POUT (VH r NrN) WRITE (6, 80) PRINT ~ HOT ILUID TEHPZRATURE ~ CALL POUT, {TH ~ N, N) llRITE (6 ~ 80) IF (IPLAG ZO. 1) GO TO 37 37 43 712 PRINTi o SOLID TEMPERATURE ~ CALL POUT (TS, H, 1) GO TO 42 WRITE (6 ~ 43) FORMAT(/, 20X, i...

Demko, Jonathan Alexander

2012-06-07T23:59:59.000Z

468

Laminated insulators having heat dissipation means  

DOE Patents (OSTI)

A laminated body is provided with heat dissipation capabilities. The insulator body is formed by dielectric layers interleaved with heat conductive layers, and bonded by an adhesive to form a composite structure. The heat conductive layers include provision for connection to an external thermal circuit.

Niemann, R.C.; Mataya, K.F.; Gonczy, J.D.

1980-04-24T23:59:59.000Z

469

Testing thermocline filler materials and molten-salt heat transfer fluids for thermal energy storage systems used in parabolic trough solar power plants.  

SciTech Connect

Parabolic trough power systems that utilize concentrated solar energy to generate electricity are a proven technology. Industry and laboratory research efforts are now focusing on integration of thermal energy storage as a viable means to enhance dispatchability of concentrated solar energy. One option to significantly reduce costs is to use thermocline storage systems, low-cost filler materials as the primary thermal storage medium, and molten nitrate salts as the direct heat transfer fluid. Prior thermocline evaluations and thermal cycling tests at the Sandia National Laboratories' National Solar Thermal Test Facility identified quartzite rock and silica sand as potential filler materials. An expanded series of isothermal and thermal cycling experiments were planned and implemented to extend those studies in order to demonstrate the durability of these filler materials in molten nitrate salts over a range of operating temperatures for extended timeframes. Upon test completion, careful analyses of filler material samples, as well as the molten salt, were conducted to assess long-term durability and degradation mechanisms in these test conditions. Analysis results demonstrate that the quartzite rock and silica sand appear able to withstand the molten salt environment quite well. No significant deterioration that would impact the performance or operability of a thermocline thermal energy storage system was evident. Therefore, additional studies of the thermocline concept can continue armed with confidence that appropriate filler materials have been identified for the intended application.

Kelly, Michael James; Hlava, Paul Frank; Brosseau, Douglas A.

2004-07-01T23:59:59.000Z

470

RODCON: a finite difference heat conduction computer code in cylindrical coordinates  

SciTech Connect

RODCON, a finite difference computer code, was developed to calculate the internal temperature distribution of the fuel rod simulator (FRS) for the Core Flow Test Loop (CFTL). RODCON solves the implicit, time-dependent forward-differencing heat transfer equation in 2-dimensional (Rtheta) cylindrical coordinates at an axial plane with user specified radial material zones and surface conditions at the FRS periphery. Symmetry of the boundary conditions of coolant bulk temperatures and film coefficients at the FRS periphery is not necessary.

Conklin, J.C.

1980-09-16T23:59:59.000Z

471

Electrical and Thermal Conductivity of Ge/Si Quantum Dot Superlattices  

E-Print Network (OSTI)

. Good carrier mobility and electric con- ductivity are important for thermoelectric materials where-Riverside, Riverside, California 92521, USA Recently proposed thermoelectric applications of quantum dot superlattices made of different material systems depend crucially on the values of the electrical and thermal

472

Heat transfer in channels with porous inserts during forced fluid flow  

Science Journals Connector (OSTI)

General analytic expressions are obtained to calculate heat transfer and temperature fields in a plane channel ... allowance for the effective thermal conductivity of the heat carrier and the distribution of heat

A. A. Plakseev; V. V. Kharitonov

1989-01-01T23:59:59.000Z

473

Spring 2014 Heat Transfer -1  

E-Print Network (OSTI)

Spring 2014 1 Heat Transfer - 1 Consider a cylindrical nuclear fuel rod of length L and diameter df and the tube at a rate m , and the outer surface of the tube is well insulated. Heat generation occurs within. The specific heat of water pc , and the thermal conductivity of the fuel rod fk are constants. The system

Virginia Tech

474

Thermal performance analysis of a direct-expansion solar-assisted heat pump water heater  

Science Journals Connector (OSTI)

A direct-expansion solar-assisted heat pump water heater (DX-SAHPWH) is described, which can supply hot water for domestic use during the whole year. The system mainly employs a bare flat-plate collector/evaporator with a surface area of 4.2 m2, an electrical rotary-type hermetic compressor, a hot water tank with the volume of 150 L and a thermostatic expansion valve. R-22 is used as working fluid in the system. A simulation model based on lumped and distributed parameter approach is developed to predict the thermal performance of the system. Given the structure parameters, meteorological parameters, time step and final water temperature, the numerical model can output operational parameters, such as heat capacity, system COP and collector efficiency. Comparisons between the simulation results and the experimental measurements show that the model is able to give satisfactory predictions. The effect of various parameters, including solar radiation, ambient temperature, wind speed and compressor speed, has been analyzed on the thermal performance of the system.

X.Q. Kong; D. Zhang; Y. Li; Q.M. Yang

2011-01-01T23:59:59.000Z

475

Mixed convection in the thermal entrance region of symmetrically and asymmetrically heated vertical flat duct with upward or downward air-flow  

SciTech Connect

A numerical investigation has been conducted on the effect of body force on pure forced convection of the upward or downward air-flow in the thermal entrance region between vertical parallel plates with uniform wall temperature. The governing equations based on the usual Boussinesq approximation are solved for the symmetrically and asymmetrically heated parallel plates. Numerically predicted friction factors C{sub f} and local Nusselt numbers Nu{sub x} are compared with their counterparts, C*{sub f} and Nu*{sub x}, for pure forced convection.

Naito, Etsuro; Nagano, Yasutaka

1999-07-01T23:59:59.000Z

476

Heat Generation and Flow and Thermal Effects on Optical Spectra in Laser Diode Pumped Thulium-doped Vanadate Crystals  

Science Journals Connector (OSTI)

Optical spectra, excited state relaxation dynamics and thermal conductivity in a wide temperature region for thulium-doped YVO4, GdVO4 and LuVO4 have been measured and analyzed to...

Lisiecki, Radoslaw; Stachowiak, Piotr; Jezowski, Andrzej; Solarz, Piotr; Dominiak-Dzik, Grazyna; Ryba-Romanowski, Witold; Lukasiewicz, Tadeusz

477

Heat conduction: a telegraph-type model with self-similar behavior of solutions  

E-Print Network (OSTI)

For heat flux $q$ and temperature $T$ we introduce a modified Fourier--Cattaneo law $q_t+ l \\frac{q}{t}= - kT_x .$ The consequence of it is a non-autonomous telegraph-type equation. % $\\epsilon S_{tt} + \\frac{a}{t} S_t = S_{xx}$ . This model already has a typical self-similar solution which may be written as product of two travelling waves modulo a time-dependent factor and might play a role of intermediate asymptotics.

Imre Ferenc Barna; Robert Kersner

2010-02-04T23:59:59.000Z

478

Heat transfer in microsphere insulation  

Science Journals Connector (OSTI)

The results of an investigation of heat transfer in a new type of insulation (microsphere insulation) are presented. The effects of the ... gas pressure on the thermal conductivity of the insulation were investig...

R. Wawryk; J. Rafa?owicz

479

Steady- and transient-state analyses of fully ceramic microencapsulated fuel loaded reactor core via two-temperature homogenized thermal-conductivity model  

Science Journals Connector (OSTI)

Abstract Fully ceramic microencapsulated (FCM) fuel, a type of accident-tolerant fuel (ATF), consists of TRISO particles randomly dispersed in a SiC matrix. In this study, for a thermal analysis of the FCM fuel with such a high heterogeneity, a two-temperature homogenized thermal-conductivity model was applied by the authors. This model provides separate temperatures for the fuel-kernels and the SiC matrix. It also provides more realistic temperature profiles than those of harmonic- and volumetric-average thermal conductivity models, which are used for thermal analysis of a fuel element in \\{VHTRs\\} having a composition similar to the FCM fuel, because such models are unable to provide the fuel-kernel and graphite matrix temperatures separately. In this study, coupled with a neutron diffusion model, a FCM fuel-loaded reactor core is analyzed via a two-temperature homogenized thermal-conductivity model at steady- and transient-states. The results are compared to those from harmonic- and volumetric-average thermal conductivity models, i.e., we compare keff eigenvalues, power distributions, and temperature profiles in the hottest single-channel at steady-state. At transient-state, we compare total powers, reactivity, and maximum temperatures in the hottest single-channel obtained by the different thermal analysis models. The different thermal analysis models and the availability of fuel-kernel temperatures in the two-temperature homogenized thermal-conductivity model for Doppler temperature feedback cause significant differences as revealed by comparisons.

Yoonhee Lee; Nam Zin Cho

2015-01-01T23:59:59.000Z