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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

Effect of heat treatment temperature on binder thermal conductivities  

SciTech Connect

The effect of heat treatment on the thermal conductivities of a pitch and a polyfurfuryl alcohol binder residue was investigated. Graphites specially prepared with these two binders were used for the experiments. Measured thermal conductivities were treated in terms of a two-component system, and the binder thermal conductivities were calculated. Both binder residues showed increased thermal conductivity with increased heat treatment temperature. (auth)

Wagner, P.

1975-12-01T23:59:59.000Z

2

Three Modes of Heat Transferâ??Thermal Conduction, Thermal Convection,  

Science Conference Proceedings (OSTI)

...).46, 44, 43, 42, 41, 40, 39, 38, 37, Ref 1In induction heating, all three modes of heat transferâ??conduction,

3

Heat Conduction  

Science Conference Proceedings (OSTI)

Table 2   Differential equations for heat conduction in solids...conduction in solids General form with variable thermal properties General form with constant thermal properties General form, constant properties, without heat

4

3 omega method for specific heat and thermal conductivity measurements  

E-Print Network (OSTI)

We present a 3 omega method for simultaneously measuring the specific heat and thermal conductivity of a rod- or filament-like specimen using a way similar to a four-probe resistance measurement. The specimen in this method needs to be electrically conductive and with a temperature-dependent resistance, for acting both as a heater to create a temperature fluctuation and as a sensor to measure its thermal response. With this method we have successfully measured the specific heat and thermal conductivity of platinum wire specimens at cryogenic temperatures, and measured those thermal quantities of tiny carbon nanotube bundles some of which are only 10^-9 g in mass.

L. Lu; W. Yi; D. L. Zhang

2002-02-06T23:59:59.000Z

5

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

6

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

Science Conference Proceedings (OSTI)

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

7

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

Open Energy Info (EERE)

Temperature, thermal-conductivity, and heat-flux data,Raft River area, Cassia County, Idaho (1974-1976) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Report:...

8

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

9

Novel Charging Station and Computational Modeling for High Thermal Conductivity Heat Pipe Thermal Ground Planes.  

E-Print Network (OSTI)

??Thermal ground planes (TGPs) are planar, thin (thickness of 3 mm or less) heat pipes which use two-phase heat transfer. TGPs are innovative high-performance, integrated… (more)

Ababneh, Mohammed

2012-01-01T23:59:59.000Z

10

Preliminary study on improvement of cementitious grout thermal conductivity for geothermal heat pump applications  

DOE Green Energy (OSTI)

Preliminary studies were preformed to determine whether thermal conductivity of cementitious grouts used to backfill heat exchanger loops for geothermal heat pumps could be improved, thus improving efficiency. Grouts containing selected additives were compares with conventional bentonite and cement grouts. Significant enhancement of grout alumina grit, steel fibers, and silicon carbide increased the thermal conductivity when compared to unfilled, high solids bentonite grouts and conventional cement grouts. Furthermore, the developed grouts retained high thermal conductivity in the dry state, where as conventional bentonite and cement grouts tend to act as insulators if moisture is lost. The cementitious grouts studied can be mixed and placed using conventional grouting equipment.

Allan, M.L.

1996-06-01T23:59:59.000Z

11

Thermal conductivity of cementitious grouts for geothermal heat pumps. Progress report FY 1997  

DOE Green Energy (OSTI)

Grout is used to seal the annulus between the borehole and heat exchanger loops in vertical geothermal (ground coupled, ground source, GeoExchange) heat pump systems. The grout provides a heat transfer medium between the heat exchanger and surrounding formation, controls groundwater movement and prevents contamination of water supply. Enhanced heat pump coefficient of performance (COP) and reduced up-front loop installation costs can be achieved through optimization of the grout thermal conductivity. The objective of the work reported was to characterize thermal conductivity and other pertinent properties of conventional and filled cementitious grouts. Cost analysis and calculations of the reduction in heat exchanger length that could be achieved with such grouts were performed by the University of Alabama. Two strategies to enhance the thermal conductivity of cementitious grouts were used simultaneously. The first of these was to incorporate high thermal conductivity filler in the grout formulations. Based on previous tests (Allan and Kavanaugh, in preparation), silica sand was selected as a suitable filler. The second strategy was to reduce the water content of the grout mix. By lowering the water/cement ratio, the porosity of the hardened grout is decreased. This results in higher thermal conductivity. Lowering the water/cement ratio also improves such properties as permeability, strength, and durability. The addition of a liquid superplasticizer (high range water reducer) to the grout mixes enabled reduction of water/cement ratio while retaining pumpability. Superplasticizers are commonly used in the concrete and grouting industry to improve rheological properties.

Allan, M.L.

1997-11-01T23:59:59.000Z

12

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-source heat pump is developed. The impact of soil thermal conductivity and pipe thermal conductivity on the soil temperature field around the buried pipe, and the thermal performance of the heat exchanger are simulated. The simulation results show that with the increase of soil thermal conductivity, heat transfer quantity obviously increases, and the temperature of soil around pipe decrease under winter conditions. The temperature field varies relatively faster with thermal conductivity in the site nearer to the buried pipe. With the increase of pipe thermal conductivity, heat transfer quantity and the mean temperature of the buried pipe's outside surface all increase.

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

2006-01-01T23:59:59.000Z

13

Influence of the temperature dependence of thermal parameters of heat conduction models on the reconstruction of thermal history of igneous-intrusion-bearing basins  

Science Conference Proceedings (OSTI)

Heat conduction models are important tools for reconstructing the thermal history of sedimentary basins affected by magmatic intrusions. Accurate thermal properties of the intrusion and its wall rocks are crucial for accurate predictions of thermal history. ... Keywords: Igneous intrusion, Peak temperature, Specific heat, Thermal conductivity, Vitrinite reflectance

Dayong Wang; Xiancai Lu; Yongchen Song; Rong Shao; Tian Qi

2010-10-01T23:59:59.000Z

14

Cylindrical thermal contact conductance  

E-Print Network (OSTI)

Thermal contact conductance is highly important in a wide variety of applications, from the cooling of electronic chips to the thermal management of spacecraft. The demand for increased efficiency means that components need to withstand higher temperatures and heat transfer rates. Many situations call for contact heat transfer through nominally cylindrical interfaces, yet relatively few studies of contact conductance through cylindrical interfaces have been undertaken. This study presents a review of the experimental and theoretical investigations of the heat transfer characteristics of composite cylinders, presenting data available in open literature in comparison with relevant correlations. The present investigation presents a study of the thermal contact conductance of cylindrical interfaces. The experimental investigation of sixteen different material combinations offers an opportunity to develop predictive correlations of the contact conductance, in conjunction with an analysis of the interface pressure as a function of the thermal state of the individual cylindrical shells. Experimental results of the present study are compared with previously published conductance data and conductance models.

Ayers, George Harold

2003-08-01T23:59:59.000Z

15

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

DOE Green Energy (OSTI)

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

16

Simulated evolution of fractures and fracture networks subject to thermal cooling: A coupled discrete element and heat conduction model  

SciTech Connect

Advancement of EGS requires improved prediction of fracture development and growth during reservoir stimulation and long-term operation. This, in turn, requires better understanding of the dynamics of the strongly coupled thermo-hydro-mechanical (THM) processes within fractured rocks. We have developed a physically based rock deformation and fracture propagation simulator by using a quasi-static discrete element model (DEM) to model mechanical rock deformation and fracture propagation induced by thermal stress and fluid pressure changes. We also developed a network model to simulate fluid flow and heat transport in both fractures and porous rock. In this paper, we describe results of simulations in which the DEM model and network flow & heat transport model are coupled together to provide realistic simulation of the changes of apertures and permeability of fractures and fracture networks induced by thermal cooling and fluid pressure changes within fractures. Various processes, such as Stokes flow in low velocity pores, convection-dominated heat transport in fractures, heat exchange between fluid-filled fractures and solid rock, heat conduction through low-permeability matrices and associated mechanical deformations are all incorporated into the coupled model. The effects of confining stresses, developing thermal stress and injection pressure on the permeability evolution of fracture and fracture networks are systematically investigated. Results are summarized in terms of implications for the development and evolution of fracture distribution during hydrofracturing and thermal stimulation for EGS.

Huang, Hai; Plummer, Mitchell; Podgorney, Robert

2013-02-01T23:59:59.000Z

17

Thermal conductivity of aqueous foam  

Science Conference Proceedings (OSTI)

Thermal conductivity plays an important part in the response of aqueous foams used as geothermal drilling fluids. The thermal conductivity of these foams was measured at ambient conditions using the thermal conductivity probe technique. Foam densities studied were from 0.03 to 0.2 g/cm/sup 3/, corresponding to liquid volume fractions of the same magnitude. Microscopy of the foams indicated bubble sizes in the range 50 to 300 ..mu..m for nitrogen foams, and 30 to 150 ..mu..m for helium foams. Bubble shapes were observed to be polyhedral at low foam densities and spherical at the higher densities. The measured conductivity values ranged from 0.05 to 0.12 W/m-K for the foams studied. The predicted behavior in foam conductivity caused by a change in the conductivity of the discontinuous gas phase was observed using nitrogen or helium gas in the foams. Analysis of the probe response data required an interpretation using the full intergral solution to the heat conduction equation, since the thermal capacity of the foam was small relative to the thermal mass of the probe. The measurements of the thermal conductivity of the foams were influenced by experimental effects such as the probe input power, foam drainage, and the orientation of the probe and test cell. For nitrogen foams, the thermal conductivity vs liquid volume fraction was observed to fall between predictions based on the parallel ordering and Russell models for thermal conduction in heterogeneous materials.

Drotning, W.D.; Ortega, A.; Havey, P.E.

1982-05-01T23:59:59.000Z

18

Thermally Conductive Graphite Foam  

oriented graphite planes, similar to high performance carbon fibers, which have been estimated to exhibit a thermal conductivity greater than 1700 ...

19

Thermal conductivity Measurements of Kaolite  

Science Conference Proceedings (OSTI)

Testing was performed to determine the thermal conductivity of Kaolite 1600, which primarily consists of Portland cement and vermiculite. The material was made by Thermal Ceramics for refractory applications. Its combination of light weight, low density, low cost, and noncombustibility made it an attractive alternative to the materials currently used in ES-2 container for radioactive materials. Mechanical properties and energy absorption tests of the Kaolite have been conducted at the Y-12 complex. Heat transfer is also an important factor for the application of the material. The Kaolite samples are porous and trap moisture after extended storage. Thermal conductivity changes as a function of moisture content below 100 C. Thermal conductivity of the Kaolite at high temperatures (up to 700 C) are not available in the literature. There are no standard thermal conductivity values for Kaolite because each sample is somewhat different. Therefore, it is necessary to measure thermal conductivity of each type of Kaolite. Thermal conductivity measurements will help the modeling and calculation of temperatures of the ES-2 containers. This report focuses on the thermal conductivity testing effort at ORNL.

Wang, H

2003-02-21T23:59:59.000Z

20

Effects of axial heat conduction and material properties on the performance characteristics of a thermal transient anemometer probe  

Science Conference Proceedings (OSTI)

This paper describes an investigation of the axial heat transfer within a thermal transient anemometer probe. A previous study, evaluated the performance characteristics of a thermal transient anemometer system. The study revealed discrepancies between a simplified theory and test results in the development of a universal calibration curve for probes of varying diameters. Although the cause of these discrepancies were left uncertain due to an inadequate theoretical model, the study suggested that axial conduction within the probe could account for the deviations. In this paper, computer simulations are used to further investigate axial heat conduction within the probes. The effect on calibration of axial variations of material properties along the probes is also discussed. Results from the computer simulation are used in lieu of the theoretical model used in the previous study to develop a satisfactory universal calibration curve. The computer simulations provide evidence that there is significant axial heat conduction within the probes, and that this was the cause of the discrepancies noted in the previous study.

Bailey, J.L.; Page, R.J. [Argonne National Lab., IL (United States); Acharya, M. [Illinois Inst. of Technology, Chicago, IL (United States). Fluid Dynamics Research Center

1995-07-01T23:59:59.000Z

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.


21

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

DOE Green Energy (OSTI)

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

22

High temperature thermal conductivity measurements of UO/sub 2/ by Direct Electrical Heating. Final report. [MANTRA-III  

SciTech Connect

High temperature properties of reactor type UO/sub 2/ pellets were measured using a Direct Electrical Heating (DEH) Facility. Modifications to the experimental apparatus have been made so that successful and reproducible DEH runs may be carried out while protecting the pellets from oxidation at high temperature. X-ray diffraction measurements on the UO/sub 2/ pellets have been made before and after runs to assure that sample oxidation has not occurred. A computer code has been developed that will model the experiment using equations that describe physical properties of the material. This code allows these equations to be checked by comparing the model results to collected data. The thermal conductivity equation for UO/sub 2/ proposed by Weilbacher has been used for this analysis. By adjusting the empirical parameters in Weilbacher's equation, experimental data can be matched by the code. From the several runs analyzed, the resulting thermal conductivity equation is lambda = 1/4.79 + 0.0247T/ + 1.06 x 10/sup -3/ exp(-1.62/kT/) - 4410. exp(-3.71/kT/) where lambda is in w/cm K, k is the Boltzman constant, and T is the temperature in Kelvin.

Bassett, B

1980-10-01T23:59:59.000Z

23

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 tests have been carried out in petrochemical plants and power plants throughout the country. Some insulating materials have been found to lose up to 60% of their insulating value after a few years in service. Calcium silicate insulations were found to be the most durable.

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

1979-01-01T23:59:59.000Z

24

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

25

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

26

THERMAL CONDUCTIVITY ANALYSIS OF GASES  

DOE Patents (OSTI)

This patent describes apparatus for the quantitative analysis of a gaseous mixture at subatmospheric pressure by measurement of its thermal conductivity. A heated wire forms one leg of a bridge circuit, while the gas under test is passed about the wire at a constant rate. The bridge unbalance will be a measure of the change in composition of the gas, if compensation is made for the effect due to gas pressure change. The apparatus provides a voltage varying with fluctuations of pressure in series with the indicating device placed across the bridge, to counterbalance the voltage change caused by fluctuations in the pressure of the gaseous mixture.

Clark, W.J.

1949-06-01T23:59:59.000Z

27

Thermal conductivity of thermal-battery insulations  

DOE Green Energy (OSTI)

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

Guidotti, R.A.; Moss, M.

1995-08-01T23:59:59.000Z

28

Nanoscale heat conduction across tunnel junctions  

E-Print Network (OSTI)

?2005? Nanoscale heat conduction across tunnel junctions Y.May 2005? Nanoscale heat conduction across tunnel junctionsprevailing theory of heat conduction in highly disordered

Ju, Y. Sungtaek; Hung, M T; Carey, M J; Cyrille, M C; Childress, J R

2005-01-01T23:59:59.000Z

29

Nanoscale thermal transport and the thermal conductance of interfaces  

E-Print Network (OSTI)

absorption depends on temperature of the nanotube · Assume heat capacity is comparable to graphite · Cooling conductance · Pump probe apparatus · Transient absorption ­ Carbon nanotubes and thermal transport at hard optical absorption of nanoparticles and nanotubes in liquid suspensions. ­ Measure the thermal relaxation

Braun, Paul

30

Thermal Conduction in Graphene and Graphene Multilayers  

E-Print Network (OSTI)

E. , and Ju, Y. S. , “ Heat conduction in novel electronicBalandin, A. A. , “Heat conduction in graphene: experimentalD. , “Simulation of heat conduction in suspended graphene

Ghosh, Suchismita

2009-01-01T23:59:59.000Z

31

Reduced Thermal Conductivity of Compacted Silicon Nanowires  

E-Print Network (OSTI)

Chen, “Coherent Phonon Heat Conduction in Superlattices,”1 Chapter 1: Heat Conduction in Nanostructured Materialsfindings. Chapter 1: Heat Conduction in Nanostructured

Yuen, Taylor S.

32

An Innovative High Thermal Conductivity Fuel Design  

SciTech Connect

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

Jamil A. Khan

2009-11-21T23:59:59.000Z

33

Hamilton-Jacobi and quantum theory formulations of thermal-wave propagation under the dual-phase lagging model of heat conduction  

SciTech Connect

Dual-phase lagging model is one of the most promising approaches to generalize the Fourier heat conduction equation, and it can be reduced in the appropriate limits to the hyperbolic Cattaneo-Vernotte and to the parabolic equations. In this paper it is shown that the Hamilton-Jacobi and quantum theory formulations that have been developed to study the thermal-wave propagation in the Fourier framework can be extended to include the more general approach based on dual-phase lagging. It is shown that the problem of solving the heat conduction equation can be treated as a thermal harmonic oscillator. In the classical approach a formulation in canonical variables is presented. This formalism is used to introduce a quantum mechanical approach from which the expectation values of observables such as the temperature and heat flux are obtained. These formalisms permit to use a methodology that could provide a deeper insight into the phenomena of heat transport at different time scales in media with inhomogeneous thermophysical properties.

Ordonez-Miranda, J.; Alvarado-Gil, J. J. [Department of Applied Physics, Cinvestav-Unidad Merida, Carretera Antigua a Progreso km. 6, A.P. Postal 73 'Cordemex', Merida, Yucatan 97310 (Mexico); Zambrano-Arjona, Miguel A. [Facultad de Ingenieria, Universidad Autonoma de Yucatan, A.P. 150 Cordemex, Merida, Yucatan 97310 (Mexico)

2010-02-15T23:59:59.000Z

34

Thermal Conduction in Graphene and Graphene Multilayers  

E-Print Network (OSTI)

1 1.2 Thermal transport atxv Introduction xii 1.1 Thermal conductivity and65 4.13 Thermal conductivity of graphene as a function of

Ghosh, Suchismita

2009-01-01T23:59:59.000Z

35

Thermal conductivity of mass-graded graphene flakes  

E-Print Network (OSTI)

In this letter we investigate thermal conductions in mass-graded graphene flakes by nonequilibrium molecular dynamics simulations. It shows mass-graded graphene flakes reveal no thermal rectification effect in thermal conduction process. Dependences of thermal conductivity upon the heat fluxes and the mass gradients are studied. It is found that thermal conductivity would be dramatically decreased by increasing the mass gradients. We also discuss the influence of thermal curvatures and thermal expansions upon the thermal conduction process in mass-graded graphene flakes.

Cheh, Jigger

2011-01-01T23:59:59.000Z

36

Gas storage carbon with enhanced thermal conductivity  

DOE Patents (OSTI)

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

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

2000-01-01T23:59:59.000Z

37

Numerical analysis of heat transfer by conduction and natural convection in loose-fill fiberglass insulation--effects of convection on thermal performance  

SciTech Connect

A two-dimensional code for solving equations of convective heat transfer in porous media is used to analyze heat transfer by conduction and convection in the attic insulation configuration. The particular cases treated correspond to loose-fill fiberglass insulation, which is characterized by high porosity and air permeability. The effects of natural convection on the thermal performance of the insulation are analyzed for various densities, permeabilities, and thicknesses of insulation. With convection increasing the total heat transfer through the insulation, the thermal resistance was found to decrease as the temperature difference across the insulating material increases. The predicted results for the thermal resistance are compared with data obtained in the large-scale climate simulator at the Roof Research Center using the attic test module, where the same phenomenon has already been observed. The way the wood joists within the insulation influence the start of convection is studied for differing thermophysical and dynamic properties of the insulating material. The presence of wood joists induces convection at a lower temperature difference.

Delmas, A.A.; Wilkes, K.E.

1992-04-01T23:59:59.000Z

38

Transient heat flux shielding using thermal metamaterials  

E-Print Network (OSTI)

We have developed a heat shield based on a metamaterial engineering approach to shield a region from transient diffusive heat flow. The shield is designed with a multilayered structure to prescribe the appropriate spatial profile for heat capacity, density, and thermal conductivity of the effective medium. The heat shield was experimentally compared to other isotropic materials.

Narayana, Supradeep; Sato, Yuki

2013-01-01T23:59:59.000Z

39

A Model of Heat Conduction  

E-Print Network (OSTI)

We define a deterministic ``scattering'' model for heat conduction which is continuous in space, and which has a Boltzmann type flavor, obtained by a closure based on memory loss between collisions. We prove that this model has, for stochastic driving forces at the boundary, close to Maxwellians, a unique non-equilibrium steady state.

Collet, Pierre

2008-01-01T23:59:59.000Z

40

Invert Effective Thermal Conductivity Calculation  

SciTech Connect

The objective of this calculation is to evaluate the temperature-dependent effective thermal conductivities of a repository-emplaced invert steel set and surrounding ballast material. The scope of this calculation analyzes a ballast-material thermal conductivity range of 0.10 to 0.70 W/m {center_dot} K, a transverse beam spacing range of 0.75 to 1.50 meters, and beam compositions of A 516 carbon steel and plain carbon steel. Results from this calculation are intended to support calculations that identify waste package and repository thermal characteristics for Site Recommendation (SR). This calculation was developed by Waste Package Department (WPD) under Office of Civilian Radioactive Waste Management (OCRWM) procedure AP-3.12Q, Revision 1, ICN 0, Calculations.

M.J. Anderson; H.M. Wade; T.L. Mitchell

2000-03-17T23:59:59.000Z

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

Umklapp Scattering and Heat Conductivity of Superlattices  

E-Print Network (OSTI)

The mean free path of phonons in superlattices is estimated. It is shown to be strongly dependent on the superlattice period due to the Umklapp scattering in subbands. It first falls with increasing the superlattice period until it becomes comparable with the latter after what it rises back to the bulk value. Similar behavior is expected of heat conductivity, which is proportional to the mean free path. Superlattices offer an opportunity to control physical properties in unprecedented ways. Their thermal conductivity is of interest both for a fundamental understanding of these systems as well as in applications. Recently there has been a resurgence of interest in finding materials with improved thermoelectric transport properties for cooling and power generation. The quality of a material for such applications is given by the thermoelectric figure of merit, which is inversely proportional to the thermal conductivity ?. In materials of interest, such as semiconductors, the lattice contribution to ? dominates. Experimental and theoretical work suggests that the thermal conductivity of superlattices is quite low, both for transport along the planes [1, 2, 10], or perpendicular to the planes [3, 4, 5, 6, 7, 8, 11]. The lattice heat conductivity ? is given approximately by an equation [12]:

M. V. Simkin; G. D. Mahan

2000-01-01T23:59:59.000Z

42

Thermally activated heat pumps  

SciTech Connect

This article describes research to develop efficient gas-fired heat pumps heat and cool buildings without CFCs. Space heating and cooling use 46% of all energy consumed in US buildings. Air-conditioning is the single leading cause of peak demand for electricity and is a major user of chlorofluorocarbons (CFCs). Advanced energy conversion technology can save 50% of this energy and eliminate CFCs completely. Besides saving energy, advanced systems substantially reduce emissions of carbon dioxide (a greenhouse gas), sulfur dioxide, and nitrogen oxides, which contribute to smog and acid rain. These emissions result from the burning of fossil fuels used to generate electricity. The Office of Building Technologies (OBT) of the US Department of Energy supports private industry`s efforts to improve energy efficiency and increase the use of renewable energy in buildings. To help industry, OBT, through the Oak Ridge National Laboratory, is currently working on thermally activated heat pumps. OBT has selected the following absorption heat pump systems to develop: generator-absorber heat-exchange (GAX) cycle for heating-dominated applications in residential and light commercial buildings; double-condenser-coupled (DCC) cycle for commercial buildings. In addition, OBT is developing computer-aided design software for investigating the absorption cycle.

NONE

1995-05-01T23:59:59.000Z

43

Heat Pipe Embedded AlSiC Plates for High Conductivity - Low CTE Heat Spreaders  

SciTech Connect

Heat pipe embedded aluminum silicon carbide (AlSiC) plates are innovative heat spreaders that provide high thermal conductivity and low coefficient of thermal expansion (CTE). Since heat pipes are two phase devices, they demonstrate effective thermal conductivities ranging between 50,000 and 200,000 W/m-K, depending on the heat pipe length. Installing heat pipes into an AlSiC plate dramatically increases the plate’s effective thermal conductivity. AlSiC plates alone have a thermal conductivity of roughly 200 W/m-K and a CTE ranging from 7-12 ppm/ deg C, similar to that of silicon. An equivalent sized heat pipe embedded AlSiC plate has effective thermal conductivity ranging from 400 to 500 W/m-K and retains the CTE of AlSiC.

Johnson, Matthew (DOE/NNSA Kansas City Plant (United States)); Weyant, J.; Garner, S. (Advanced Cooling Technologies, Inc. (Lancaster, PA (United States)); Occhionero, M. (CPS Technologies Corporation, Norton, MA (United States))

2010-01-07T23:59:59.000Z

44

Nitrogen heat pipe for cryocooler thermal shunt  

SciTech Connect

A nitrogen heat pipe was designed, built and tested for the purpose of providing a thermal shunt between the two stages of a Gifford-McMahan (GM) cryocooler during cooldown. The nitrogen heat pipe has an operating temperature range between 63 and 123 K. While the heat pipe is in the temperature range during the system cooldown, it acts as a thermal shunt between the first and second stage of the cryocooler. The heat pipe increases the heat transfer to the first stage of the cryocooler, thereby reducing the cooldown time of the system. When the heat pipe temperature drops below the triple point, the nitrogen working fluid freezes, effectively stopping the heat pipe operation. A small heat leak between cryocooler stages remains because of axial conduction along the heat pipe wall. As long as the heat pipe remains below 63 K, the heat pipe remains inactive. Heat pipe performance limits were measured and the optimum fluid charge was determined.

Prenger, F.C.; Hill, D.D.; Daney, D.E.; Daugherty, M.A. [Los Alamos National Lab., NM (United States); Green, G.F.; Roth, E.W. [Naval Surface Warfare Center, Annapolis, MD (United States)

1995-09-01T23:59:59.000Z

45

Thermal conduction in cosmological SPH simulations  

E-Print Network (OSTI)

Thermal conduction in the intracluster medium has been proposed as a possible heating mechanism for offsetting central cooling losses in rich clusters of galaxies. In this study, we introduce a new formalism to model conduction in a diffuse ionised plasma using smoothed particle hydrodynamics (SPH), and we implement it in the parallel TreePM/SPH-code GADGET-2. We consider only isotropic conduction and assume that magnetic suppression can be described in terms of an effective conductivity, taken as a fixed fraction of the temperature-dependent Spitzer rate. We also account for saturation effects in low-density gas. Our formulation manifestly conserves thermal energy even for individual and adaptive timesteps, and is stable in the presence of small-scale temperature noise. This allows us to evolve the thermal diffusion equation with an explicit time integration scheme along with the ordinary hydrodynamics. We use a series of simple test problems to demonstrate the robustness and accuracy of our method. We then ...

Jubelgas, M; Dolag, K

2004-01-01T23:59:59.000Z

46

Thermal Conductivity Database of Various Structural Carbon-Carbon  

Science Conference Proceedings (OSTI)

Advanced thermal protection materials envisioned for use on future hypersonic vehicles will likely be subjected to temperatures in excess of 1811 K (2800F) and, therefore, will require the rapid conduction of heat away from the stagnation regions of ...

Ohlhorst Craig W.; Vaughn Wallace L.; Ransone Philip O.; Tsou Hwa-Tsu

1997-11-01T23:59:59.000Z

47

Experimental investigations of solid-solid thermal interface conductance  

E-Print Network (OSTI)

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

Collins, Kimberlee C. (Kimberlee Chiyoko)

2010-01-01T23:59:59.000Z

48

Variable conductance heat pipe enhancement  

SciTech Connect

This patent describes a heat pipe. It comprises a tubular hollow heat pipe having an evaporator end and an opposite condenser end, the heat pipe having a cross-sectional area and having a condenser length extending from the condenser end the condenser length including an active length where evaporated fluid condenses; an evaporatable and condensable fluid in the heat pipe for evaporating when receiving heat near the evaporation end and for condensing when giving up heat in the active length; a noncondensable gas near the condenser end and in the condenser length of the heat pipe; a restriction member fixed in the heat pipe near the condenser end, the restriction member extending only along a portion of the condenser length and being spaced away from the evaporation end of the heat pipe, the restriction member having a varied cross-sectional area along the length of the restriction member which is less than the cross-sectional area of the heat pipe for confining the gas and a portion of the fluid in the active condenser length, to an area around the restriction member and in the heat pipe; and a fixed ligament connected between the restriction member and the heat pipe for fixing the restriction member in the heat pipe, the ligament being fixed between the condenser end of the heat pipe end and an end of the restriction member which is closest to the condenser end.

Kneidel, K.E.

1991-09-03T23:59:59.000Z

49

Thermal conductivity and other properties of cementitious grouts  

DOE Green Energy (OSTI)

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

Allan, M.

1998-08-01T23:59:59.000Z

50

THERMAL CONDUCTIVITY AND OTHER PROPERTIES OF CEMENTITIOUS GROUTS  

DOE Green Energy (OSTI)

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

ALLAN,M.

1998-05-01T23:59:59.000Z

51

Conductive Thermal Interaction in Evaporative Cooling Process  

E-Print Network (OSTI)

It has long been recognized that evaporative cooling is an effective and logical substitute for mechanical cooling in hot-arid climates. This paper explores the application of evaporative coolers to the hot-humid climates using a controlled temperature of the incoming water. With exploitation of the effect of the thermal conduction between cool underground water and entering air, the performance of an evaporative cooler can be enhanced and its use in hot and moderately humid climates should also be considered. Usually the dry-bulb depression performed by an evaporative cooler depends solely on the ambient wet-bulb temperature. The cool underground water in an evaporative cooler can cause not only adiabatic evaporation but also sensible heat transfer between water and entering air for thermal comfort. This hybrid system outperforms the two-stage evaporative cooler without employing a complicated heat exchanger (indirect system), if the temperature of underground water is lower than the ambient wet-bulb temperature. Several areas in the southern hot-humid parts of the U.S. meet this condition.

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

1990-01-01T23:59:59.000Z

52

Correlation Between Thermal Conductivity and Microstructural ...  

Science Conference Proceedings (OSTI)

Characterization of MOX fuel pellets by Photothermal microscopy · Correlation Between Thermal Conductivity and Microstructural Evolutions in CeO2 Upon ...

53

Splitting schemes for hyperbolic heat conduction equation  

E-Print Network (OSTI)

Rapid processes of heat transfer are not described by the standard heat conduction equation. To take into account a finite velocity of heat transfer, we use the hyperbolic model of heat conduction, which is connected with the relaxation of heat fluxes. In this case, the mathematical model is based on a hyperbolic equation of second order or a system of equations for the temperature and heat fluxes. In this paper we construct for the hyperbolic heat conduction equation the additive schemes of splitting with respect to directions. Unconditional stability of locally one-dimensional splitting schemes is established. New splitting schemes are proposed and studied for a system of equations written in terms of the temperature and heat fluxes.

Vabishchevich, Petr N

2010-01-01T23:59:59.000Z

54

Solar Thermal Process Heat | Open Energy Information  

Open Energy Info (EERE)

Process Heat Jump to: navigation, search TODO: Add description List of Solar Thermal Process Heat Incentives Retrieved from "http:en.openei.orgwindex.php?titleSolarThermalPr...

55

Nanoscale Heat Conduction across Metal-Dielectric Interfaces  

E-Print Network (OSTI)

006 " Nanoscale Heat Conduction across Metal-Dielectricdirectly. Nanoscale Heat Conduction across Metal-Dielectricstudy of nanoscale heat conduction across nanolaminates

Ju, Y. Sungtaek

2005-01-01T23:59:59.000Z

56

Thermal Response Testing for Geothermal Heat Exchangers ...  

Science Conference Proceedings (OSTI)

Thermal Response Testing for Geothermal Heat Exchangers Begins. The Net-Zero house features a geothermal heat pump ...

2013-03-12T23:59:59.000Z

57

Heat conductivity in linear mixing systems  

E-Print Network (OSTI)

We present analytical and numerical results on the heat conduction in a linear mixing system. In particular we consider a quasi one dimensional channel with triangular scatterers with internal angles irrational multiples of pi and we show that the system obeys Fourier law of heat conduction. Therefore deterministic diffusion and normal heat transport which are usually associated to full hyperbolicity, actually take place in systems without exponential instability.

Baowen Li; Giulio Casati; Jiao Wang

2002-08-06T23:59:59.000Z

58

Electron thermal conduction in LASNEX  

SciTech Connect

This report is a transcription of hand-written notes by DM dated 29 January 1986, transcribed by SW, with some clarifying comments added and details specific to running the LASNEX code deleted. Reference to the esoteric measurement units employed in LASNEX has also been deleted by SW (hopefully, without introducing errors in the numerical constants). The report describes the physics equations only, and only of electron conduction. That is, it does not describe the numerical method, which may be finite difference or finite element treatment in space, and (usually) implicit treatment in time. It does not touch on other electron transport packages which are available, and which include suprathermal electrons, nonlocal conduction, Krook model conduction, and modifications to electron conduction by magnetic fields. Nevertheless, this model is employed for the preponderance of LASNEX simulations.

Munro, D.; Weber, S.

1994-12-16T23:59:59.000Z

59

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)

The objective of this research was to determine the effect of thermal cycling combined with mechanical loading on the development of microcracks in M40J/PMR-II- 50, the second generation aerospace application material. The objective was pursued by finding the critical controlling parameters for microcrack formation from mechanical stress-thermal cycling test. Three different in-plane strains (0%, 0.175~0.350%, and 0.325~0.650%) were applied to the composites by clamping composite specimens (M40J/PMR-II-50, [0,90]s, a unitape cross-ply) on the radial sides of half cylinders having two different radii (78.74mm and 37.96mm). Three different thermal loading experiments, 1) 23oC to �196oC to 250oC, 2) 23oC to 250oC, and 3) 23oC to -196oC, were performed as a function of mechanical inplane strain levels, heating rates, and number of thermal cycles. The apparatus generated cracks related to the in-plane stresses (or strains) on plies. The design and analysis concept of the synergistic stress-thermal cycling experiment was simplified to obtain main and interaction factors by applying 2k factorial design from the various factors affecting microcrack density of M40J/PMR-II-50. Observations indicate that the higher temperature portion of the cycle under load causes fiber/matrix interface failure. Subsequent exposure to higher stresses in the cryogenic temperature region results in composite matrix microcracking due to the additional stresses associated with the fiber-matrix thermal expansion mismatch.

Ju, Jaehyung

2005-08-01T23:59:59.000Z

60

Equilibrium Models of Galaxy Clusters with Cooling, Heating and Conduction  

E-Print Network (OSTI)

It is generally argued that most clusters of galaxies host cooling flows in which radiative cooling in the centre causes a slow inflow. However, recent observations by Chandra and XMM conflict with the predicted cooling flow rates. Amongst other mechanisms, heating by a central active galactic nucleus and thermal conduction have been invoked in order to account for the small mass deposition rates. Here, we present a family of hydrostatic models for the intra-cluster medium where radiative losses are exactly balanced by thermal conduction and heating by a central source. We describe the features of this simple model and fit its parameters to the density and temperature profiles of Hydra A.

M. Bruggen

2003-03-20T23:59:59.000Z

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.


61

Increased thermal conductivity monolithic zeolite structures  

SciTech Connect

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

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

2008-11-25T23:59:59.000Z

62

Information filtering via biased heat conduction  

E-Print Network (OSTI)

Heat conduction process has recently found its application in personalized recommendation [T. Zhou \\emph{et al.}, PNAS 107, 4511 (2010)], which is of high diversity but low accuracy. By decreasing the temperatures of small-degree objects, we present an improved algorithm, called biased heat conduction (BHC), which could simultaneously enhance the accuracy and diversity. Extensive experimental analyses demonstrate that the accuracy on MovieLens, Netflix and Delicious datasets could be improved by 43.5%, 55.4% and 19.2% compared with the standard heat conduction algorithm, and the diversity is also increased or approximately unchanged. Further statistical analyses suggest that the present algorithm could simultaneously identify users' mainstream and special tastes, resulting in better performance than the standard heat conduction algorithm. This work provides a creditable way for highly efficient information filtering.

Liu, Jian-Guo; Guo, Qiang

2011-01-01T23:59:59.000Z

63

Thermal Conductivity and Shear Strength of K Basin Sludge  

DOE Green Energy (OSTI)

Hanford K Basin sludge contains metallic uranium and uranium oxides that will corrode, hydrate, and, consequently, generate heat and hydrogen gas during storage. Heat is generated within the K Basin sludge by radiolytic decay and the reaction of uranium metal with water. To maintain thermal stability, the sludge must be retrieved, staged, transported, and stored in systems designed to provide a rate of heat removal that prevents the temperature in the sludge from increasing beyond acceptable limits. To support the dispositioning of the sludge to T Plant, modeling and testing and analyses are being performed to predict the behavior of sludge when placed into the storage containers. Two physical properties of the sludge that are critical to the modeling and analyses efforts are thermal conductivity and the sludge shear strength (yield stress). This report provides the results of thermal conductivity and shear strength measurements performed on representative sludge samples from the K East Basin.

Poloski, Adam P. (BATTELLE (PACIFIC NW LAB)); Bredt, Paul R. (BATTELLE (PACIFIC NW LAB)); Schmidt, Andrew J. (BATTELLE (PACIFIC NW LAB)); Swoboda, Robert G. (BATTELLE (PACIFIC NW LAB)); Chenault, Jeffrey W. (BATTELLE (PACIFIC NW LAB)); Gano, Sue (BATTELLE (PACIFIC NW LAB))

2002-05-17T23:59:59.000Z

64

Electrical Conduction, Heat Conduction, Shear Viscosity and Entropy  

E-Print Network (OSTI)

We present here how to study steady linear transport phenomena by using entropy. We study the system and the environment together and identify their entropies. Concerning their interaction, quantum mechanics is considered. A time parameter $\\tau$ is therefore introduced to characterize the discrete nature of the quantum interactions. By combining $\\tau$ and the entropy, an approach is constructed successfully to study electrical conduction, heat conduction and shear viscosity

Zhang, Yong-Jun

2010-01-01T23:59:59.000Z

65

High Thermal Conductivity AlN Materials  

Science Conference Proceedings (OSTI)

AlN has replaced BeO as the high thermal conductivity ceramic of choice due to the adverse health effects associated with BeO. The development of high ...

66

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

67

Thermal conductivity modeling of building façade materials  

Science Conference Proceedings (OSTI)

An experimental research has been conducted to assess the thermo-physical properties of three building materials in both dry and moist state: beech wood, autoclaved aerated concrete and brick. The objectives of the paper envisage the measurement of the ... Keywords: building materials, contact temperature, determining method, finite element, numerical modeling, thermal conductivity

Monica Chereches; Nelu-Cristian Chereches; Catalin Popovici

2010-04-01T23:59:59.000Z

68

Thermal conductivity of $sup 238$PuO$sub 2$ powder, intermediates, and dense fuel forms  

SciTech Connect

The thermal conductivities of porous $sup 238$PuO$sub 2$ powder (calcined oxalate), milled powder, and high-density granules were calculated from direct measurements of steady-state temperature profiles resulting from self- heating. Thermal conductivities varied with density, temperature, and gas content of the pores. Errors caused by thermocouple heat conduction were less than 5 percent when the dimensions of the thermal conductivity cell and the thermocouple were properly selected. (auth)

Bickford, D.F.; Crain, B. Jr.

1975-10-01T23:59:59.000Z

69

Correlations and scaling in one-dimensional heat conduction J. M. Deutsch and Onuttom Narayan  

E-Print Network (OSTI)

Correlations and scaling in one-dimensional heat conduction J. M. Deutsch and Onuttom Narayan of the heat current, through the Kubo formula, gives a thermal conductivity exponent of 1/3 in agreement.40.Mg I. INTRODUCTION Heat conduction in one-dimensional systems is a simple example of the general

California at Santa Cruz, University of

70

Matrix heat exchanger including a liquid, thermal couplant  

DOE Patents (OSTI)

A tube-to-tube heat exchanger is disclosed with a thermally conductive matrix between and around the tubes to define annuli between the tubes and matrix. The annuli are filled to a level with a molten metal or alloy to provide a conductive heat transfer path from one tube through the matrix to the second tube. A matrix heat exchanger of this type is particularly useful for heat transfer between fluids which would react should one leak into the second.

Fewell, Thomas E. (Chattanooga, TN); Ward, Charles T. (Chattanooga, TN)

1976-01-01T23:59:59.000Z

71

Transitioning water to an enhanced heat-conducting phase  

E-Print Network (OSTI)

Water can be transitioned to an enhanced heat-conducting phase by supercooling only the water at the bottom of a container. The temperature gradient across the 4 cm in the center of an 8 cm long column of water with a 397 mW heat source at the top was lowered from 32oC to 0.75oC when the temperature at the bottom of the column was lowered from 1.2 oC to -5.6oC. The effective thermal conductivity of the water was increased from ~0.607 W/mK to ~24 W/mK. This result demonstrates that water has a high effective thermal conducting phase that has not been previously reported.

Brownridge, James D

2011-01-01T23:59:59.000Z

72

Finite Heat conduction in 2D Lattices  

E-Print Network (OSTI)

This paper gives a 2D hamonic lattices model with missing bond defects, when the capacity ratio of defects is enough large, the temperature gradient can be formed and the finite heat conduction is found in the model. The defects in the 2D harmonic lattices impede the energy carriers free propagation, by another words, the mean free paths of the energy carrier are relatively short. The microscopic dynamics leads to the finite conduction in the model.

Lei Yang; Yang Kongqing

2001-07-30T23:59:59.000Z

73

Implicit continuum mechanics approach to heat conduction in granular materials  

SciTech Connect

In this paper, we derive a properly frame-invariant implicit constitutive relationship for the heat flux vector for a granular medium (or a density-gradient-type fluid). The heat flux vector is commonly modeled by Fourier’s law of heat conduction, and for complex materials such as nonlinear fluids, porous media, or granular materials, the coefficient of thermal conductivity is generalized by assuming that it would depend on a host of material and kinematic parameters such as temperature, shear rate, porosity, concentration, etc. In this paper, we extend the approach of Massoudi [Massoudi, M. Math. Methods Appl. Sci. 2006, 29, 1585; Massoudi, M. Math. Methods Appl. Sci. 2006, 29, 1599], who provided explicit constitutive relations for the heat flux vector for flowing granular materials; in order to do so, we use the implicit scheme suggested by Fox [Fox, N. Int. J. Eng. Sci. 1969, 7, 437], who obtained implicit relations in thermoelasticity.

Massoudi, M.; Mehrabadi, M.

2010-01-01T23:59:59.000Z

74

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

75

Finite Heat conduction in 2D Lattices  

E-Print Network (OSTI)

This paper gives a 2D hamonic lattices model with missing bond defects, when the capacity ratio of defects is enough large, the temperature gradient can be formed and the finite heat conduction is found in the model. The defects in the 2D harmonic lattices impede the energy carriers free propagation, by another words, the mean free paths of the energy carrier are relatively short. The microscopic dynamics leads to the finite conduction in the model. PACS numbers: 44.10. +I, 05.45.Jn, 05.60.-k, 05.70.Ln The study of heat conduction in models of insulating solids is a rather old and debated problem, and the more general problem is one of understanding the nonequilibrium energy current carrying state of a many body system. The most of the work on heat conduction investigated the process of heat transport in 1D lattices. The different models have been studied for obtaining Fourier’s law, several kinds of factors have been taken into account in the models, such as the nonlinearity, on-site potentials, mass disorder and etc. Then the typical 1D lattices Hamiltonian is

Lei Yang; Yang Kongqing

2001-01-01T23:59:59.000Z

76

Heat conduction in graphite-nanoplatelet-reinforced polymer nanocomposites  

E-Print Network (OSTI)

89, 023117 ?2006? Heat conduction in graphite-nanoplatelet-The resistance to heat conduction across interfaces between?DOI: 10.1063/1.2221874? Heat conduction across surfaces of

Hung, M T; Choi, O; Ju, Y. Sungtaek; Hahn, H T

2006-01-01T23:59:59.000Z

77

Thermal Conductivity of Cubic and Hexagonal Mesoporous Silica Thin Films  

E-Print Network (OSTI)

K.L. Fang, “Anisotropic thermal conductivity of nanoporousmesoporous silica as a thermal isolation layer”, Ceramicsand V. Wittwer, “Some thermal and optical properties of a

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

2009-01-01T23:59:59.000Z

78

VALIDATION OF A THERMAL CONDUCTIVITY MEASUREMENT SYSTEM FOR FUEL COMPACTS  

SciTech Connect

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

Jeff Phillips; Colby Jensen; Changhu Xing; Heng Ban

2011-03-01T23:59:59.000Z

79

Thermal conductivity of dense quark matter and cooling of stars  

E-Print Network (OSTI)

The thermal conductivity of the color-flavor locked phase of dense quark matter is calculated. The dominant contribution to the conductivity comes from photons and Nambu-Goldstone bosons associated with breaking of baryon number which are trapped in the quark core. Because of their very large mean free path the conductivity is also very large. The cooling of the quark core arises mostly from the heat flux across the surface of direct contact with the nuclear matter. As the thermal conductivity of the neighboring layer is also high, the whole interior of the star should be nearly isothermal. Our results imply that the cooling time of compact stars with color-flavor locked quark cores is similar to that of ordinary neutron stars.

Igor A. Shovkovy; Paul J. Ellis

2002-04-11T23:59:59.000Z

80

Conductive heat flow in the Randsburg area, California  

DOE Green Energy (OSTI)

The Randsburg known Geothermal Resource Area (KGRA) is located in a tectonically active part of the Mojave Desert just south of the Garlock Fault. To provide background information for geothermal resource appraisal, the results from five holes drilled for regional heat-flow reconnaissance (USGS, unpublished data) were combined with data from nine additional holes drilled especially as part of this study in an attempt to delineate the conductive thermal anomaly associated with observed geothermal manifestations in the Randsburg area.

Sass, J.H.; Galanis, S.P. Jr.; Marshall, B.V.; Lachenbruch, A.H.; Munroe, R.J.; Moses, T.H. Jr.

1978-01-01T23:59:59.000Z

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.


81

Pretest Caluculations of Temperature Changes for Field Thermal Conductivity Tests  

Science Conference Proceedings (OSTI)

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

N.S. Brodsky

2002-07-17T23:59:59.000Z

82

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

83

Role of Brownian Motion Hydrodynamics on Nanofluid Thermal Conductivity  

Science Conference Proceedings (OSTI)

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

W Evans, J Fish, P Keblinski

2005-11-14T23:59:59.000Z

84

Heat Exchanger Thermal Performance Margin Guidelines  

Science Conference Proceedings (OSTI)

This report provides utility engineers with guidance on how to identify the thermal performance margin that is available in a given heat exchanger by comparing the thermal performance requirement at design limiting conditions to the thermal performance capability of the heat exchanger under those same conditions.

2005-11-30T23:59:59.000Z

85

Reduced Thermal Conductivity of Compacted Silicon Nanowires  

E-Print Network (OSTI)

Nanoscale Heat Transfer Processes …. ………………………………. 7 1.4:1.3 – Nanoscale Heat Transfer Processes When studying heat

Yuen, Taylor S.

86

Phonon Heat Conduction In A Semiconductor Nanowire  

E-Print Network (OSTI)

ic phonon dispersion due to spatial confinement, and (ii) change in the nonequilibrium phonon distribution due to partially diffuse boundary scattering. Numerical simulation is performed for a silicon nanowire with boundaries characterized by different interface roughness. Phonon confinement and boundary scattering lead to a significant decrease of the lattice thermal conductivity. The value of this decrease and its interface roughness and temperature dependence are different from the predictions of the early models. The observed change in thermal resistance has to be taken into account in simulation of deepsubmicron and nanometer-scale devices. 2001 American Institute of Physics. PACS: 68.65.La, 66.70.+f, 63.22.+m, 68.35. References

Joe Zou; Alexander Balandin; Jie Zou; Er Bal

2000-01-01T23:59:59.000Z

87

Determining the temperature field for cylinder symmetrical heat conduction problems in unsteady heat conduction in finite space  

Science Conference Proceedings (OSTI)

This paper proposes to present a new method to calculate unsteady heat conduction for cylinder symmetrical geometry. We will investigate the situation where the temperature field and heat flux created around a heat source placed in finite space are determined. ... Keywords: Garbai's integral equation, Laplace transformation, determining the temperate field, district heating pipes, geothermal producing pipe, heat flux density, heat loss, heat pump

László Garbai; Szabolcs Méhes

2007-05-01T23:59:59.000Z

88

Effects of air infiltration on the effective thermal conductivity...  

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

Effects of air infiltration on the effective thermal conductivity of internal fiberglass insulation and on the delivery of thermal capacity via ducts Title Effects of air...

89

Frostless heat pump having thermal expansion valves  

DOE Patents (OSTI)

A heat pump system having an operable relationship for transferring heat between an exterior atmosphere and an interior atmosphere via a fluid refrigerant and further having a compressor, an interior heat exchanger, an exterior heat exchanger, a heat pump reversing valve, an accumulator, a thermal expansion valve having a remote sensing bulb disposed in heat transferable contact with the refrigerant piping section between said accumulator and said reversing valve, an outdoor temperature sensor, and a first means for heating said remote sensing bulb in response to said outdoor temperature sensor thereby opening said thermal expansion valve to raise suction pressure in order to mitigate defrosting of said exterior heat exchanger wherein said heat pump continues to operate in a heating mode.

Chen, Fang C [Knoxville, TN; Mei, Viung C [Oak Ridge, TN

2002-10-22T23:59:59.000Z

90

Numerical Model for Conduction-Cooled Current Lead Heat Loads  

SciTech Connect

Current leads are utilized to deliver electrical power from a room temperature junction mounted on the vacuum vessel to a superconducting magnet located within the vacuum space of a cryostat. There are many types of current leads used at laboratories throughout the world; however, conduction-cooled current leads are often chosen for their simplicity and reliability. Conduction-cooled leads have the advantage of using common materials, have no superconducting/normal state transition, and have no boil-off vapor to collect. This paper presents a numerical model for conduction-cooled current lead heat loads. This model takes into account varying material and fluid thermal properties, varying thicknesses along the length of the lead, heat transfer in the circumferential and longitudinal directions, electrical power dissipation, and the effect of thermal intercepts. The model is validated by comparing the numerical model results to ideal cases where analytical equations are valid. In addition, the XFEL (X-Ray Free Electron Laser) prototype current leads are modeled and compared to the experimental results from testing at DESY's XFEL Magnet Test Stand (XMTS) and Cryomodule Test Bench (CMTB).

White, M.J.; Wang, X.L.; /Fermilab; Brueck, H.D.; /DESY

2011-06-10T23:59:59.000Z

91

The Effect of Soil Thermal Conductivity Parameterization on Surface Energy Fluxes and Temperatures  

Science Conference Proceedings (OSTI)

The sensitivity of sensible and latent heat fluxes and surface temperatures to the parameterization of the soil thermal conductivity is demonstrated using a soil vegetation atmosphere transfer scheme (SVATS) applied to intensive field campaigns (...

C. D. Peters-Lidard; E. Blackburn; X. Liang; E. F. Wood

1998-04-01T23:59:59.000Z

92

Heat conduction in X-ray clusters: Spitzer over 3  

E-Print Network (OSTI)

Effective heat conduction in a random variable magnetic field should be equal to one third of the Spitzer's value. Recent observations indicate that this heat conduction is sufficient to account for the bremsstrahlung in cooling X-ray clusters.

Andrei Gruzinov

2002-03-04T23:59:59.000Z

93

High thermal conductivity connector having high electrical isolation  

DOE Patents (OSTI)

A method and article for providing a low-thermal-resistance, high-electrical-isolation heat intercept connection. The connection method involves clamping, by thermal interference fit, an electrically isolating cylinder between an outer metallic ring and an inner metallic disk. The connection provides durable coupling of a heat sink and a heat source.

Nieman, Ralph C. (Downers Grove, IL); Gonczy, John D. (Oak Lawn, IL); Nicol, Thomas H. (St. Charles, IL)

1995-01-01T23:59:59.000Z

94

Reduced Thermal Conductivity of Compacted Silicon Nanowires  

E-Print Network (OSTI)

alpha1=k1/(density1*cp1); %Thermal diffusivity of PMMA B1=Simon R. Phillpot, “Nanoscale Thermal Transport”, Journal of9] E.T. Swartz, R.O. Pohl, “Thermal Boundary Resistance”,

Yuen, Taylor S.

95

Ab-Initio Thermal Conductivity for Thermoelectric Nanostructured ...  

Science Conference Proceedings (OSTI)

About this Abstract. Meeting, 2012 TMS Annual Meeting & Exhibition. Symposium , Energy Nanomaterials. Presentation Title, Ab-Initio Thermal Conductivity for ...

96

Heat conduction in 2D strongly-coupled dusty plasmas  

E-Print Network (OSTI)

We perform non-equilibrium simulations to study heat conduction in two-dimensional strongly coupled dusty plasmas. Temperature gradients are established by heating one part of the otherwise equilibrium system to a higher temperature. Heat conductivity is measured directly from the stationary temperature profile and heat flux. Particular attention is paid to the influence of damping effect on the heat conduction. It is found that the heat conductivity increases with the decrease of the damping rate, while its magnitude confirms previous experimental measurement.

Hou, Lu-Jing

2008-01-01T23:59:59.000Z

97

The evolution of interstellar clouds in a streaming hot plasma including heat conduction  

E-Print Network (OSTI)

To examine the evolution of giant molecular clouds in the stream of a hot plasma we performed two-dimensional hydrodynamical simulations that take full account of self-gravity, heating and cooling effects and heat conduction by electrons. We use the thermal conductivity of a fully ionized hydrogen plasma proposed by Spitzer and a saturated heat flux according to Cowie & McKee in regions where the mean free path of the electrons is large compared to the temperature scaleheight. Significant structural and evolutionary differences occur between simulations with and without heat conduction. Dense clouds in pure dynamical models experience dynamical destruction by Kelvin-Helmholtz (KH) instability. In static models heat conduction leads to evaporation of such clouds. Heat conduction acting on clouds in a gas stream smooths out steep temperature and density gradients at the edge of the cloud because the conduction timescale is shorter than the cooling timescale. This diminishes the velocity gradient between the...

Vieser, W

2007-01-01T23:59:59.000Z

98

Method for determining thermal conductivity and thermal capacity per unit volume of earth in situ  

DOE Patents (OSTI)

A method for determining the thermal conductivity of the earth in situ is based upon a cylindrical probe (10) having a thermopile (16) for measuring the temperature gradient between sets of thermocouple junctions (18 and 20) of the probe after it has been positioned in a borehole and has reached thermal equilibrium with its surroundings, and having means (14) for heating one set of thermocouple junctions (20) of the probe at a constant rate while the temperature gradient of the probe is recorded as a rise in temperature over several hours (more than about 3 hours). A fluid annulus thermally couples the probe to the surrounding earth. The recorded temperature curves are related to the earth's thermal conductivity, k.sub..infin., and to the thermal capacity per unit volume, (.gamma.c.sub.p).sub..infin., by comparison with calculated curves using estimates of k.sub..infin. and (.gamma.c.sub.p).sub..infin. in an equation which relates these parameters to a rise in the earth's temperature for a known and constant heating rate.

Poppendiek, Heinz F. (LaJolla, CA)

1982-01-01T23:59:59.000Z

99

Integrated heat pipe-thermal storage system performance evaluation  

SciTech Connect

Performance verification tests of an integrated heat pipe-thermal energy storage system have been conducted. This system is being developed as a part of an Organic Rankine Cycle-Solar Dynamic Power System (ORC-SDPS) receiver for future space stations. The integrated system consists of potassium heat pipe elements that incorporate thermal energy storage (TES) canisters within the vapor space along with an organic fluid (toluene) heater tube used as the condenser region of the heat pipe. During the insolation period of the earth orbit, solar energy is delivered to the surface of the heat pipe elements of the ORC-SDPS receiver and is internally transferred by the potassium vapor for use and storage. Part of the thermal energy is delivered to the heater tube and the balance is stored in the TES units. During the eclipse period of the orbit, the stored energy in the TES units is transferred by the potassium vapor to the toluene heater tube. A developmental heat pipe element was fabricated that employs axial arteries and a distribution wick connecting the wicked TES units and the heater to the solar insolation surface of the heat pipe. Tests were conducted to verify the heat pipe operation and to evaluate the heat pipe/TES units/heater tube operation by interfacing the heater unit to a heat exchanger.

Keddy, E.; Sena, J.T.; Merrigan, M.

1987-01-01T23:59:59.000Z

100

Correlation between thermal expansion and heat capacity  

E-Print Network (OSTI)

Theoretically predicted linear correlation between the volume coefficient of thermal expansion and the thermal heat capacity was investigated for highly symmetrical atomic arrangements. Normalizing the data of these thermodynamic parameters to the Debye temperature gives practically identical curves from zero Kelvin to the Debye temperature. This result is consistent with the predicted linear correlation. At temperatures higher than the Debye temperature the normalized values of the thermal expansion are always higher than the normalized value of the heat capacity. The detected correlation has significant computational advantage since it allows calculating the volume coefficient of thermal expansion from one experimental data by using the Debye function.

Jozsef Garai

2004-04-25T23:59:59.000Z

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

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

102

Thermal Inertia of Conductivity Cells: Theory  

Science Conference Proceedings (OSTI)

The temperature anomaly of a fluid moving through circular and rectangular cylinders induced by the heat stored in the walls of these hollow cylinders is derived under the assumption of quasi-steady heat transfer. These geometries correspond ...

Rolf G. Lueck

1990-10-01T23:59:59.000Z

103

On Thermally Forced Circulations over Heated Terrain  

Science Conference Proceedings (OSTI)

A combination of analytical and numerical models is used to gain insight into the dynamics of thermally forced circulations over diurnally heated terrain. Solutions are obtained for two-layer flows (representing the boundary layer and the ...

Daniel J. Kirshbaum

2013-06-01T23:59:59.000Z

104

Heat recovery and thermal storage : a study of the Massachusetts State Transportation Building  

E-Print Network (OSTI)

A study of the energy system at the Massachusetts State Transportation Building was conducted. This innovative energy system utilizes internal-source heat pumps and a water thermal storage system to provide building heating ...

Bjorklund, Abbe Ellen

1986-01-01T23:59:59.000Z

105

Thermal Conductivity Measurements of Thermoelectric Films  

Science Conference Proceedings (OSTI)

... which allow solid-state conversion of thermal to electrical energy, have a ... and exhaust system, which can run either an electric motor or accessories ...

2013-03-15T23:59:59.000Z

106

Breaking the Thermal Conductivity Glass Limit  

Science Conference Proceedings (OSTI)

High Thermal Energy Storage Density LiNO3-KNO3-NaNO2-KNO2 Quaternary Molten Salt System for Parabolic Trough Concentrating Solar Power Generation.

107

Effects of Composition and Granulometry on Thermal Conductivity of ...  

Science Conference Proceedings (OSTI)

It has been observed that thermal conductivity of cover material is strongly ... Experimental Investigation of Single Bubble Characteristics in a Cold Model of a ... Creep on Potroom Busbars and Electrical Insulation: Thermal-Electrical Aspects.

108

Assembly and testing of a composite heat pipe thermal intercept for HTS current leads  

SciTech Connect

We are building high temperature superconducting (HTS) current leads for a demonstration HTS-high gradient magnetic separation (HGMS) system cooled by a cryocooler. The current leads are entirely conductively cooled. A composite nitrogen heat pipe provides efficient thermal communication, and simultaneously electrical isolation, between the lead and an intermediate temperature heat sink. Data on the thermal and electrical performance of the heat pipe thermal intercept are presented. The electrical isolation of the heat pipe was measured as a function of applied voltage with and without a thermal load across the heat pipe. The results show the electrical isolation with evaporation, condensation and internal circulation taking place in the heat pipe.

Daugherty, M.A.; Daney, D.E.; Prenger, F.C.; Hill, D.D.; Williams, P.M.; Boenig, H.J.

1995-09-01T23:59:59.000Z

109

Effects of Joule Heating on One-Dimensional Heat Conduction of Sn ...  

Science Conference Proceedings (OSTI)

In order to clarify the basic understanding of Joule heating effect and corresponding mechanism of heat conduction, solder joints with same cross-

110

Superfluid Heat Conduction and the Cooling of Magnetized Neutron Stars  

SciTech Connect

We report on a new mechanism for heat conduction in the neutron star crust. We find that collective modes of superfluid neutron matter, called superfluid phonons, can influence heat conduction in magnetized neutron stars. They can dominate the heat conduction transverse to the magnetic field when the magnetic field B > or approx. 10{sup 13} G. At a density of {rho}{approx_equal}10{sup 12}-10{sup 14} g/cm{sup 3}, the conductivity due to superfluid phonons is significantly larger than that due to lattice phonons and is comparable to electron conductivity when the temperature {approx_equal}10{sup 8} K. This new mode of heat conduction can limit the surface anisotropy in highly magnetized neutron stars. Cooling curves of magnetized neutron stars with and without superfluid heat conduction could show observationally discernible differences.

Aguilera, Deborah N. [Tandar Laboratory, Comision Nacional de Energia Atomica, Avenida Gral. Paz 1499, 1650 San Martin, Buenos Aires (Argentina); Cirigliano, Vincenzo; Reddy, Sanjay; Sharma, Rishi [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Pons, Jose A. [Department of Applied Physics, University of Alicante, Apartado de Correos 99, E-03080 Alicante (Spain)

2009-03-06T23:59:59.000Z

111

Superfluid heat conduction and the cooling of magnetized neutron stars  

SciTech Connect

We report on a new mechanism for heat conduction in the neutron star crust. We find that collective modes of superftuid neutron matter, called superfiuid phonons (sPhs), can influence heat conduction in magnetized neutron stars. They can dominate the heat conduction transverse to magnetic field when the magnetic field B {approx}> 10{sup 13} C. At density p {approx_equal} 10{sup 12}--10{sup 14} g/cm{sup 3} the conductivity due to sPhs is significantly larger than that due to lattice phonons and is comparable to electron conductivity at when temperature {approx_equal} 10{sup 8} K. This new mode of heat conduction can limit the surface anisotropy in highly magnetized neutron stars. Cooling curves of magnetized neutron stars with and without superfluid heat conduction show observationally discernible differences.

Cirigliano, Vincenzo [Los Alamos National Laboratory; Reddy, Sanjay [Los Alamos National Laboratory; Sharma, Rishi [Los Alamos National Laboratory; Aguilera, Deborah N [BUENOS AIRES

2008-01-01T23:59:59.000Z

112

Superfluid Heat Conduction and the Cooling of Magnetized Neutron Stars  

E-Print Network (OSTI)

We report on a new mechanism for heat conduction in the neutron star crust. We find that collective modes of superfluid neutron matter, called superfluid phonons (sPhs), can influence heat conduction in magnetized neutron stars. They can dominate the heat conduction transverse to magnetic field when the magnetic field $B \\gsim 10^{13}$ G. At density $\\rho \\simeq 10^{12}-10^{14} $ g/cm$^3$ the conductivity due to sPhs is significantly larger than that due to lattice phonons and is comparable to electron conductivity when temperature $\\simeq 10^8$ K. This new mode of heat conduction can limit the surface anisotropy in highly magnetized neutron stars. Cooling curves of magnetized neutron stars with and without superfluid heat conduction could show observationally discernible differences.

Aguilera, Deborah N; Pons, José A; Reddy, Sanjay; Sharma, Rishi

2008-01-01T23:59:59.000Z

113

Superfluid Heat Conduction and the Cooling of Magnetized Neutron Stars  

E-Print Network (OSTI)

We report on a new mechanism for heat conduction in the neutron star crust. We find that collective modes of superfluid neutron matter, called superfluid phonons (sPhs), can influence heat conduction in magnetized neutron stars. They can dominate the heat conduction transverse to magnetic field when the magnetic field $B \\gsim 10^{13}$ G. At density $\\rho \\simeq 10^{12}-10^{14} $ g/cm$^3$ the conductivity due to sPhs is significantly larger than that due to lattice phonons and is comparable to electron conductivity when temperature $\\simeq 10^8$ K. This new mode of heat conduction can limit the surface anisotropy in highly magnetized neutron stars. Cooling curves of magnetized neutron stars with and without superfluid heat conduction could show observationally discernible differences.

Deborah N. Aguilera; Vincenzo Cirigliano; José A. Pons; Sanjay Reddy; Rishi Sharma

2008-07-29T23:59:59.000Z

114

Long-term Atomistic Simulation of Heat Conduction and Mass ...  

Science Conference Proceedings (OSTI)

This non-equilibrium thermodynamics model is then coupled with discrete kinetic models of Onsager type which governs heat conduction and mass transport at ...

115

Thermal Conductivity Prediction of Nano Fluid Using ANN/GA  

Science Conference Proceedings (OSTI)

Abstract Scope, Thermal conductivities of nano fluid in a two-phase having different compositions of both base fluid as well as nano particles in a closed ...

116

Measuring Thermal Conductivity of Powder Insulation at Cryogenic Temperatures.  

E-Print Network (OSTI)

?? A device to measure bulk effective thermal conductivity of powder insulation at cryogenic temperatures has been designed and tested. The design consists of two… (more)

Barrios, Matthew Nicklas

2006-01-01T23:59:59.000Z

117

Mobile robot path planning algorithm by equivalent conduction heat flow topology optimization  

Science Conference Proceedings (OSTI)

This paper addresses the path planning problem for a point robot moving in a planar environment filled with obstacles. Our approach is based on the principles of thermal conduction and structural topology optimization and rests on the observation that, ... Keywords: Conduction heat flow, Mobile robot, Path planning, Topology optimization

Jae Chun Ryu; Frank Chongwoo Park; Yoon Young Kim

2012-05-01T23:59:59.000Z

118

Anisotropic Thermal Conduction and the Cooling Flow Problem in Galaxy Clusters  

E-Print Network (OSTI)

We examine the long-standing cooling flow problem in galaxy clusters with 3D MHD simulations of isolated clusters including radiative cooling and anisotropic thermal conduction along magnetic field lines. The central regions of the intracluster medium (ICM) can have cooling timescales of ~200 Myr or shorter--in order to prevent a cooling catastrophe the ICM must be heated by some mechanism such as AGN feedback or thermal conduction from the thermal reservoir at large radii. The cores of galaxy clusters are linearly unstable to the heat-flux-driven buoyancy instability (HBI), which significantly changes the thermodynamics of the cluster core. The HBI is a convective, buoyancy-driven instability that rearranges the magnetic field to be preferentially perpendicular to the temperature gradient. For a wide range of parameters, our simulations demonstrate that in the presence of the HBI, the effective radial thermal conductivity is reduced to less than 10% of the full Spitzer conductivity. With this suppression of ...

Parrish, Ian J; Sharma, Prateek

2009-01-01T23:59:59.000Z

119

Law for Thermal Conductivity of Crystalline Nanoporous Silicon Using Molecular Dynamic Simulations  

E-Print Network (OSTI)

G. A. , 2007. “Lattice thermal conductivity of nanoporousPore-size dependence of the thermal conductivity of porousand Chen, G. , 2004. “Thermal conductivity of nanoporous

Fang, Jin; Pilon, Laurent

2011-01-01T23:59:59.000Z

120

One-dimensional heat conductivity exponent from a random collision model J. M. Deutsch and Onuttom Narayan  

E-Print Network (OSTI)

One-dimensional heat conductivity exponent from a random collision model J. M. Deutsch and Onuttom to conductivity would predict that if the temperature gradient "T in a material is small, the heat current flowing January 2003; published 18 July 2003 We obtain numerically the thermal conductivity of a quasi

California at Santa Cruz, University of

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

Stability of thermal structures with an internal heating source  

E-Print Network (OSTI)

We study the thermal equilibrium and stability of isobaric, spherical structures having a radiation source located at its center. The thermal conduction coefficient, external heating and cooling rates are represented as power laws of the temperature. The internal heating decreases with distance from the source r approximately as exp(-tau)/(r**2), being tau the optical depth. We find that the influence of the radiation source is important only in the central region, but its effect is enough to make the system thermally unstable above a certain threshold central temperature. This threshold temperature decreases as the internal heating efficiency increases, but, otherwise, it does not depend on the structure size. Our results suggest that a solar-like star migrating into a diffuse interstellar region may destabilize the surrounding medium.

Sanchez, Nestor

2008-01-01T23:59:59.000Z

122

Stability of thermal structures with an internal heating source  

E-Print Network (OSTI)

We study the thermal equilibrium and stability of isobaric, spherical structures having a radiation source located at its center. The thermal conduction coefficient, external heating and cooling rates are represented as power laws of the temperature. The internal heating decreases with distance from the source r approximately as exp(-tau)/(r**2), being tau the optical depth. We find that the influence of the radiation source is important only in the central region, but its effect is enough to make the system thermally unstable above a certain threshold central temperature. This threshold temperature decreases as the internal heating efficiency increases, but, otherwise, it does not depend on the structure size. Our results suggest that a solar-like star migrating into a diffuse interstellar region may destabilize the surrounding medium.

Nestor Sanchez; Eugenio Lopez

2008-03-10T23:59:59.000Z

123

Determination of thermal parameters of one-dimensional nanostructures through a thermal transient method  

E-Print Network (OSTI)

of heat capacity and thermal conductivity measurements bythe heat pulse method for thermal transport measurements ofG. Speci?c heat and thermal conductivity measurements on

Arriagada, A.; Yu, E. T.; Bandaru, P. R.

2009-01-01T23:59:59.000Z

124

Linear and nonlinear transient heat conduction in nuclear waste repositories  

Science Conference Proceedings (OSTI)

Analytical solutions of thermal problems connected with the disposal of nuclear wastes are presented. Linear and nonlinear diffusion problems are analyzed considering time-dependent heat sources. Comparisons between the temperature distributions at a ...

C. A. Estrada-Gasca; M. H. Cobble

1988-10-01T23:59:59.000Z

125

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

126

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

127

Advanced Heat Transfer and Thermal Storage Fluids  

DOE Green Energy (OSTI)

The design of the next generation solar parabolic trough systems for power production will require the development of new thermal energy storage options with improved economics or operational characteristics. Current heat-transfer fluids such as VP-1?, which consists of a eutectic mixture of biphenyl and diphenyl oxide, allow a maximum operating temperature of ca. 300 C, a limit above which the vapor pressure would become too high and would require pressure-rated tanks. The use of VP-1? also suffers from a freezing point around 13 C that requires heating during cold periods. One of the goals for future trough systems is the use of heat-transfer fluids that can act as thermal storage media and that allow operating temperatures around 425 C combined with lower limits around 0 C. This paper presents an outline of our latest approach toward the development of such thermal storage fluids.

Moens, L.; Blake, D.

2005-01-01T23:59:59.000Z

128

Thermal Conduction and Multiphase Gas in Cluster Cores  

E-Print Network (OSTI)

We examine the role of thermal conduction and magnetic fields in cores of galaxy clusters through global simulations of the intracluster medium (ICM). In particular, we study the influence of thermal conduction, both isotropic and anisotropic, on the condensation of multiphase gas in cluster cores. Previous hydrodynamic simulations have shown that cold gas condenses out of the hot ICM in thermal balance only when the ratio of the cooling time ($t_{\\rm cool}$) and the free-fall time ($t_{\\rm ff}$) is less than $\\approx 10$. Since thermal conduction is significant in the ICM and it suppresses local cooling at small scales, it is imperative to include thermal conduction in such studies. We find that anisotropic (along local magnetic field lines) thermal conduction does not influence the condensation criterion for a general magnetic geometry, even if thermal conductivity is large. However, with isotropic thermal conduction cold gas condenses only if conduction is suppressed (by a factor $\\lesssim 0.3$) with respe...

Wagh, Baban; McCourt, Michael

2013-01-01T23:59:59.000Z

129

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

E-Print Network (OSTI)

fall within ~ 10%. Heat conduction through the TCs coulda 6% difference. To eliminate heat conduction effects, otherlaw formulation of heat conduction in materials. BASIC

Louie, Brian Ming

2011-01-01T23:59:59.000Z

130

The evolution of interstellar clouds in a streaming hot plasma including heat conduction  

E-Print Network (OSTI)

To examine the evolution of giant molecular clouds in the stream of a hot plasma we performed two-dimensional hydrodynamical simulations that take full account of self-gravity, heating and cooling effects and heat conduction by electrons. We use the thermal conductivity of a fully ionized hydrogen plasma proposed by Spitzer and a saturated heat flux according to Cowie & McKee in regions where the mean free path of the electrons is large compared to the temperature scaleheight. Significant structural and evolutionary differences occur between simulations with and without heat conduction. Dense clouds in pure dynamical models experience dynamical destruction by Kelvin-Helmholtz (KH) instability. In static models heat conduction leads to evaporation of such clouds. Heat conduction acting on clouds in a gas stream smooths out steep temperature and density gradients at the edge of the cloud because the conduction timescale is shorter than the cooling timescale. This diminishes the velocity gradient between the streaming plasma and the cloud, so that the timescale for the onset of KH instabilities increases, and the surface of the cloud becomes less susceptible to KH instabilities. The stabilisation effect of heat conduction against KH instability is more pronounced for smaller and less massive clouds. As in the static case more realistic cloud conditions allow heat conduction to transfer hot material onto the cloud's surface and to mix the accreted gas deeper into the cloud.

W. Vieser; G. Hensler

2007-04-26T23:59:59.000Z

131

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

132

ANISOTROPIC THERMAL CONDUCTION AND THE COOLING FLOW PROBLEM IN GALAXY CLUSTERS  

SciTech Connect

We examine the long-standing cooling flow problem in galaxy clusters with three-dimensional magnetohydrodynamics simulations of isolated clusters including radiative cooling and anisotropic thermal conduction along magnetic field lines. The central regions of the intracluster medium (ICM) can have cooling timescales of {approx}200 Myr or shorter-in order to prevent a cooling catastrophe the ICM must be heated by some mechanism such as active galactic nucleus feedback or thermal conduction from the thermal reservoir at large radii. The cores of galaxy clusters are linearly unstable to the heat-flux-driven buoyancy instability (HBI), which significantly changes the thermodynamics of the cluster core. The HBI is a convective, buoyancy-driven instability that rearranges the magnetic field to be preferentially perpendicular to the temperature gradient. For a wide range of parameters, our simulations demonstrate that in the presence of the HBI, the effective radial thermal conductivity is reduced to {approx}<10% of the full Spitzer conductivity. With this suppression of conductive heating, the cooling catastrophe occurs on a timescale comparable to the central cooling time of the cluster. Thermal conduction alone is thus unlikely to stabilize clusters with low central entropies and short central cooling timescales. High central entropy clusters have sufficiently long cooling times that conduction can help stave off the cooling catastrophe for cosmologically interesting timescales.

Parrish, Ian J.; Sharma, Prateek; Quataert, Eliot, E-mail: iparrish@astro.berkeley.ed [Astronomy Department and Theoretical Astrophysics Center, 601 Campbell Hall, University of California, Berkeley, CA 94720 (United States)

2009-09-20T23:59:59.000Z

133

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

134

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

135

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

136

The effect of heat conduction on the interaction of disk and corona around black holes  

E-Print Network (OSTI)

Heat conduction plays an important role in the balance between heating and cooling in many astrophysical objects, e.g. cooling flows in clusters of galaxies. Here we investigate the effect of heat conduction on the interaction between a cool disk and a hot corona around black holes. Using the one-radial-zone approximation, we study the vertical structure of the disk corona and derive evaporation and coronal mass flow rates for various reduced thermal conductivities. We find lower evaporation rates and a shift in the evaporation maxima to smaller radii. This implies that the spectral state transition occurs at a lower mass flow rate and a disk truncation closer to the black hole. Reductions of thermal conductivity are thought to be magnetically caused and might vary from object to object by a different configuration of the magnetic fields.

E. Meyer-Hofmeister; F. Meyer

2005-12-21T23:59:59.000Z

137

Value of solar thermal industrial process heat  

DOE Green Energy (OSTI)

This study estimated the value of solar thermal-generated industrial process heat (IPH) as a function of process heat temperature. The value of solar thermal energy is equal to the cost of producing energy from conventional fuels and equipment if the energy produced from either source provides an equal level of service. This requirement put the focus of this study on defining and characterizing conventional process heat equipment and fuels. Costs (values) were estimated for 17 different design points representing different combinations of conventional technologies, temperatures, and fuels. Costs were first estimated for median or representative conditions at each design point. The cost impact of capacity factor, efficiency, fuel escalation rate, and regional fuel price differences were then evaluated by varying each of these factors within credible ranges.

Brown, D.R.; Fassbender, L.L.; Chockie, A.D.

1986-03-01T23:59:59.000Z

138

Graphite Foam Heat Exchangers for Thermal Management  

Science Conference Proceedings (OSTI)

Improved thermal management is needed to increase the power density of electronic and more effectively cool electronic enclosures that are envisioned in future aircraft, spacecraft and surface ships. Typically, heat exchanger cores must increase in size to more effectively dissipate increased heat loads, this would be impossible in many cases, thus improved heat exchanger cores will be required. In this Phase I investigation, MRi aimed to demonstrate improved thermal management using graphite foam (Gr-foam) core heat exchangers. The proposed design was to combine Gr-foams from POCO with MRi's innovative low temperature, active metal joining process (S-Bond{trademark}) to bond Gr-foam to aluminum, copper and aluminum/SiC composite faceplates. The results were very favorable, so a Phase II SBIR with the MDA was initiated. This had primarily 5 tasks: (1) bonding, (2) thermal modeling, (3) cooling chip scale packages, (4) evaporative cooling techniques and (5) IGBT cold plate development. The bonding tests showed that the ''reflow'' technique with S-Bond{reg_sign}-220 resulted in the best and most consistent bond. Then, thermal modeling was used to design different chip scale packages and IGBT cold plates. These designs were used to fabricate many finned graphite foam heat sinks specifically for two standard type IC packages, the 423 and 478 pin chips. These results demonstrated several advantages with the foam. First, the heat sinks with the foam were lighter than the copper/aluminum sinks used as standards. The sinks for the 423 design made from foam were not as good as the standard sinks. However, the sinks made from foam for the 478 pin chips were better than the standard heat sinks used today. However, this improvement was marginal (in the 10-20% better regime). However, another important note was that the epoxy bonding technique resulted in heat sinks with similar results as that with the S-bond{reg_sign}, slightly worse than the S-bond{reg_sign}, but still better than the standard heat sinks. Next, work with evaporative cooling techniques, such as heat pipes, demonstrated some unique behavior with the foam that is not seen with standard wick materials. This was that as the thickness of the foam increased, the performance got better, where with standard wick materials, as the thickness increases, the performance decreases. This is yet to be completely explained. Last, the designs from the thermal model were used to fabricate a series of cold plates with the graphite foam and compare them to similar designs using high performance folded fin aluminum sinks (considered standard in the industry). It was shown that by corrugating the foam parallel to fluid flow, the pressure drop can be reduced significantly while maintaining the same heat transfer as that in the folded fin heat sink. In fact, the results show that the graphite foam heat sink can utilized 5% the pumping power as that required with the folded fin aluminum heat sink, yet remove the same amount of heat.

Klett, J.W.

2004-06-07T23:59:59.000Z

139

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

SciTech Connect

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

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

2011-09-28T23:59:59.000Z

140

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

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

Raman Spectroscopy of High Thermal Conductivity AlN Ceramics ...  

Science Conference Proceedings (OSTI)

Thermal conductivity of AlN ceramics was measured by laser flash method. Raman spectroscopy was used to characterize oxygen related defects of AlN ... Transport in Co-Based Materials for Fuel Cells and Oxygen Separation Membranes.

142

A benchmark study on the thermal conductivity of nanofluids  

E-Print Network (OSTI)

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

Buongiorno, Jacopo

143

Group classification for the nonlinear heat conductivity equation  

E-Print Network (OSTI)

Symmetry properties of the nonlinear heat conductivity equations of the general form $u_t=[E(x,u)u_x]_x + H(x,u)$ is studied. The point symmetry analysis of these equations is considered as well as an equivalence classification which admits an extension by one dimension of the principal Lie algebra of the equation. The invariant solutions of equivalence transformations and classification of the nonlinear heat conductivity equations among with additional operators are also given.

Mahdipour-Shirayeh, Ali

2009-01-01T23:59:59.000Z

144

Weak coupling limits in a stochastic model of heat conduction  

E-Print Network (OSTI)

We study the Brownian momentum process, a model of heat conduction, weakly coupled to heat baths. In two different settings of weak coupling to the heat baths, we study the non-equilibrium steady state and its proximity to the local equilibrium measure in terms of the strength of coupling. For three and four site systems, we obtain the two-point correlation function and show it is generically not multilinear.

Redig, Frank

2011-01-01T23:59:59.000Z

145

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.

Lopez-Monsalvo, C S

2010-01-01T23:59:59.000Z

146

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

147

Thermal Conductivity Spectroscopy Technique to Measure Phonon Mean Free Paths  

E-Print Network (OSTI)

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

Schmidt, A. J.

148

Serpentine Thermal Coupling Between a Stream and a Conducting Body  

Science Conference Proceedings (OSTI)

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

149

Low-Conductivity Thermal Barrier Coating for Gas Turbines: Material Testing Status  

Science Conference Proceedings (OSTI)

Advanced gas turbines rely on air-cooled components protected by ceramic thermal barrier coatings to survive increasingly high operating temperatures. A new generation of coatings offers lower thermal conductivity, potentially further reducing component heat loading, which can improve durability, lower life cycle cost, and enable longer range efficiency gains. Testing improved coatings is a necessary step towards field demonstration.BackgroundAs gas turbine ...

2012-12-31T23:59:59.000Z

150

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

DOE Green Energy (OSTI)

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

151

Single-photon heat conduction in electrical circuits  

E-Print Network (OSTI)

We study photonic heat conduction between two resistors coupled weakly to a single superconducting microwave cavity. At low enough temperature, the dominating part of the heat exchanged between the resistors is transmitted by single-photon excitations of the fundamental mode of the cavity. This manifestation of single-photon heat conduction should be experimentally observable with the current state of the art. Our scheme can possibly be utilized in remote interference-free temperature control of electric components and environment engineering for superconducting qubits coupled to cavities.

Jones, P J; Tan, K Y; Möttönen, M

2011-01-01T23:59:59.000Z

152

Single-photon heat conduction in electrical circuits  

E-Print Network (OSTI)

We study photonic heat conduction between two resistors coupled weakly to a single superconducting microwave cavity. At low enough temperature, the dominating part of the heat exchanged between the resistors is transmitted by single-photon excitations of the fundamental mode of the cavity. This manifestation of single-photon heat conduction should be experimentally observable with the current state of the art. Our scheme can possibly be utilized in remote interference-free temperature control of electric components and environment engineering for superconducting qubits coupled to cavities.

P. J. Jones; J. A. M. Huhtamäki; K. Y. Tan; M. Möttönen

2011-07-14T23:59:59.000Z

153

PROBLEM 13.94 KNOWN: Diameter, temperature and emissivity of boiler tube. Thermal conductivity and emissivity of  

E-Print Network (OSTI)

PROBLEM 13.94 KNOWN: Diameter, temperature and emissivity of boiler tube. Thermal conductivity of 0.5 mm), Td = 773 K nd the ash provides a significant resistance to heat transfer.a COMMENTS: Boiler

Rothstein, Jonathan

154

An Empirical Model of UO2 Thermal Conductivity Based on Laser Flash Measurements of Thermal Diffusivity  

Science Conference Proceedings (OSTI)

Thermal conductivity of irradiated fuel materials, which can be derived from measured thermal diffusivity (TD), is a key consideration in thermal performance and design of a fuel rod. However, without interpretation, the measured TD data cannot be used directly to calculate fuel temperatures during irradiation. This report provides such interpretation and presents an empirical model for the degradation of UO2 thermal conductivity with burn-up.

1998-10-07T23:59:59.000Z

155

Estimation of in-situ thermal conductivities from temperature gradient measurements  

Science Conference Proceedings (OSTI)

A mathematical model has been developed to study the effect of variable thermal conductivity of the formations, and the wellbore characteristics, on the fluid temperature behavior inside the wellbore during injection or production and after shut-in. During the injection or production period the wellbore fluid temperature is controlled mainly by the fluid flow rate and the heat lost from the fluid to the formation. During the shut-in period, the fluid temperature is strongly affected by differences in the formation thermal conductivities. Based on the results of the present analysis, two methods for estimating in-situ thermal conductivity were derived. First, the line source concept is extended to estimate values of the formation thermal conductivities utilizing the fluid temperature record during the transient period of injection or production and shut-in. The second method is applied when a well is under thermal equilibrium conditions. Values of the formation thermal conductivities can also be estimated by using a continuous temperature gradient log and by measuring the thermal conductivity of the formation at a few selected wellbore locations.

Hoang, V.T.

1980-12-01T23:59:59.000Z

156

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; Zhang, Wei [ORNL; Yu, Zhenzhen [ORNL; Feng, Zhili [ORNL

2012-01-01T23:59:59.000Z

157

High Heating Rate Thermal Desorption for Molecular Surface ...  

High Heating Rate Thermal Desorption for Molecular Surface Sampling Note: The technology described above is an early stage opportunity. Licensing ...

158

Thermal Inertia of Conductivity Cells: Observations with a Sea-Bird Cell  

Science Conference Proceedings (OSTI)

We have examined the magnitude and relaxation time of the thermal anomaly of the fluid flowing through the conductivity cell manufactured by Sea-Bird Electronics (SBE) that is induced by the heat stored in the wall of this cell using oceanic data ...

Rolf G. Lueck; James J. Picklo

1990-10-01T23:59:59.000Z

159

Thermal battery. [solid metal halide electrolytes with enhanced electrical conductance after a phase transition  

DOE Patents (OSTI)

The patent describes an improved thermal battery whose novel design eliminates various disadvantages of previous such devices. Its major features include a halide cathode, a solid metal halide electrolyte which has a substantially greater electrical conductance after a phase transition at some temperature, and a means for heating its electrochemical cells to activation temperature.

Carlsten, R.W.; Nissen, D.A.

1973-03-06T23:59:59.000Z

160

SIMULATIONS OF MAGNETOHYDRODYNAMICS INSTABILITIES IN INTRACLUSTER MEDIUM INCLUDING ANISOTROPIC THERMAL CONDUCTION  

SciTech Connect

We perform a suite of simulations of cooling cores in clusters of galaxies in order to investigate the effect of the recently discovered heat flux buoyancy instability (HBI) on the evolution of cores. Our models follow the three-dimensional magnetohydrodynamics of cooling cluster cores and capture the effects of anisotropic heat conduction along the lines of magnetic field, but do not account for the cosmological setting of clusters or the presence of active galactic nuclei (AGNs). Our model clusters can be divided into three groups according to their final thermodynamical state: catastrophically collapsing cores, isothermal cores, and an intermediate group whose final state is determined by the initial configuration of magnetic field. Modeled cores that are reminiscent of real cluster cores show evolution toward thermal collapse on a timescale which is prolonged by a factor of approx2-10 compared with the zero-conduction cases. The principal effect of the HBI is to re-orient field lines to be perpendicular to the temperature gradient. Once the field has been wrapped up onto spherical surfaces surrounding the core, the core is insulated from further conductive heating (with the effective thermal conduction suppressed to less than 10{sup -2} of the Spitzer value) and proceeds to collapse. We speculate that, in real clusters, the central AGN and possibly mergers play the role of 'stirrers', periodically disrupting the azimuthal field structure and allowing thermal conduction to sporadically heat the core.

Bogdanovic, Tamara; Reynolds, Christopher S. [Department of Astronomy, University of Maryland, College Park, MD 20742-2421 (United States); Balbus, Steven A. [Ecole Normale Superieure, Laboratoire de Radioastronomie, 24 rue Lhomond, 75231 Paris CEDEX 05 (France); Parrish, Ian J., E-mail: tamarab@astro.umd.ed, E-mail: chris@astro.umd.ed, E-mail: steven.balbus@lra.ens.f, E-mail: iparrish@astro.berkeley.ed [Astronomy Department and Theoretical Astrophysics Center, 601 Campbell Hall, University of California, Berkeley, CA 94720 (United States)

2009-10-10T23:59:59.000Z

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

Thermal Transport in Graphene Multilayers and Nanoribbons  

E-Print Network (OSTI)

80 CHAPTER 5 Heat Conduction in Few Layerto Fourier's Law of heat conduction, thermal conductivity isnext experiments on heat conduction in graphene structures

Subrina, Samia

2011-01-01T23:59:59.000Z

162

An experimental study on the thermal performance of ground heat exchanger  

Science Conference Proceedings (OSTI)

A knowledge of ground thermal properties is most important for the proper design of large GHE (ground heat exchanger) systems. Thermal response tests have so far been used primarily not only for in situ determination of design data for GHE systems, but also for the evaluation of grout material, heat exchanger types and groundwater effects. The main purpose has been to determine in situ values of effective ground thermal conductivity, including the effect of groundwater flow and natural convection in boreholes. (author)

Lim, Kyoungbin; Lee, Sanghoon [Department of Mechanical Engineering, Hanbat University, Daejon (Korea); Lee, Changhee [Department of Mechanical Engineering, Hanyang University, 1271 Sa1 Ansan, Kyungki-do 425791 (Korea)

2007-08-15T23:59:59.000Z

163

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

164

The Dynamics of Rayleigh-Taylor Stable and Unstable Contact Discontinuities with Anisotropic Thermal Conduction  

E-Print Network (OSTI)

We study the effects of anisotropic thermal conduction along magnetic field lines on an accelerated contact discontinuity in a weakly collisional plasma. We first perform a linear stability analysis similar to that used to derive the Rayleigh-Taylor instability (RTI) dispersion relation. We find that anisotropic conduction is only important for compressible modes, as incompressible modes are isothermal. Modes grow faster in the presence of anisotropic conduction, but growth rates do not change by more than a factor of order unity. We next run fully non-linear numerical simulations of a contact discontinuity with anisotropic conduction. The non-linear evolution can be thought of as a superposition of three physical effects: temperature diffusion due to vertical conduction, the RTI, and the heat flux driven buoyancy instability (HBI). In simulations with RTI-stable contact discontinuities, the temperature discontinuity spreads due to vertical heat conduction. This occurs even for initially horizontal magnetic f...

Lecoanet, Daniel; Quataert, Eliot

2012-01-01T23:59:59.000Z

165

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

166

Are X-ray Clusters Cooled by Heat Conduction to the Surrounding Intergalactic Medium?  

E-Print Network (OSTI)

We show that X-ray clusters would have cooled substantially over a Hubble time by transport of heat from their hot interior to the their envelope, if the heat conductivity had not been heavily suppressed relative to the Spitzer value due to magnetic fields. The suppression is required in order for the observed abundance of hot X-ray clusters to be consistent with predictions from popular cosmological models. If a similar or stronger suppression factor applies to cluster cores, then thermal conduction can not be the mechanism that prevents cooling flows there.

Abraham Loeb

2002-03-26T23:59:59.000Z

167

Latent Heat Thermal Energy Storage with Embedded Heat Pipes for Concentrating Solar Power Applications.  

E-Print Network (OSTI)

?? An innovative, novel concept of combining heat pipes with latent heat thermal energy storage (LHTES) for concentrating solar power (CSP) applications is explored. The… (more)

Robak, Christopher

2012-01-01T23:59:59.000Z

168

Technical Project Plan for The Enhanced Thermal Conductivity of Oxide Fuels Through the Addition of High Thermal Conductivity Fibers and Microstructural Engineering  

SciTech Connect

The commercial nuclear power industry is investing heavily in advanced fuels that can produce higher power levels with a higher safety margin and be produced at low cost. Although chemically stable and inexpensive to manufacture, the in-core performance of UO{sub 2} fuel is limited by its low thermal conductivity. There will be enormous financial benefits to any utility that can exploit a new type of fuel that is chemically stable, has a high thermal conductivity, and is inexpensive to manufacture. At reactor operating temperatures, UO{sub 2} has a very low thermal conductivity (<5 W/m {center_dot}K), which decreases with temperature and fuel burnup. This low thermal conductivity limits the rate at which energy can be removed from the fuel, thus limiting the total integrated reactor power. If the fuel thermal conductivity could be increased, nuclear reactors would be able to operate at higher powers and larger safety margins thus decreasing the overall cost of electricity by increasing the power output from existing reactors and decreasing the number of new electrical generating plants needed to meet base load demand. The objective of the work defined herein is to produce an advanced nuclear fuel based on the current UO{sub 2} fuel with superior thermal conductivity and structural integrity that is suitable for current and future nuclear reactors, using the existing fuel fabrication infrastructure with minimal modifications. There are two separate components to the research: (1) Enhanced Thermal Conductivity (ETC) - adding high conductivity fibers to the UO{sub 2} prior to sintering, which act as conduits for moving the heat energy generated within the pellet to the outer surface, (2) Microstructural Engineering (ME) - adding second phase particulates to UO{sub 2} bodies to retard grain growth and to increase thermal conductivity, as well as improve fracture and creep resistance. Different groups will perform the laboratory work for each of these research components with some overlap in personnel. The overlapping areas primarily involve computer simulations and final testing of the fuel in a reactor. The estimated cost and duration of this project is $5,000,000 over three years.

Hollenbach, Daniel F [ORNL; Ott, Larry J [ORNL; Besmann, Theodore M [ORNL; Armstrong, Beth L [ORNL; Wereszczak, Andrew A [ORNL; Lin, Hua-Tay [ORNL; Ellis, Ronald James [ORNL; Becher, Paul F [ORNL; Jubin, Robert Thomas [ORNL; Voit, Stewart L [ORNL

2010-09-01T23:59:59.000Z

169

Phase-field modeling of temperature gradient driven pore migration coupling with thermal conduction  

SciTech Connect

Pore migration in a temperature gradient (Soret effect) is investigated by a phase-field model coupled with a heat transfer calculation. Pore migration is observed towards the high temperature domain with velocities that agree with analytical solution. Due to the low thermal conductivity of the pores, the temperature gradient across individual pores is increased, which in turn, accelerates the pore migration. In particular, for pores filled with xenon and helium, the pore velocities are increased by a factor of 2.2 and 2.1, respectively. A quantitative equation is then derived to predict the influence of the low thermal conductivity of pores.

Liangzhe Zhang; Michael R Tonks; Paul C Millett; Yongfeng Zhang; Karthikeyan Chockalingam; Bulent Biner

2012-04-01T23:59:59.000Z

170

Assessing the RELAPS-3D Heat Conduction Enclosure Model  

SciTech Connect

Three heat conduction problems that have exact solutions are modeled with RELAP5-3D using the conduction enclosure model. These comparisons are designed to be used in the RELAP5-3D development assessment scheduled to be completed in 2009. It is shown that with proper input choices and adequate model detail the exact solutions can be matched. In addition, this analysis identified an error and the required correction in the cylindrical and spherical heat conductor models in RELAP5-3D which will be corrected in a future version of RELAP5-3D.

McCann, Larry D.

2008-09-30T23:59:59.000Z

171

A mechanical model for Fourier's law of heat conduction  

E-Print Network (OSTI)

Nonequilibrium statistical mechanics close to equilibrium is a physically satisfactory theory centered on the linear response formula of Green-Kubo. This formula results from a formal first order perturbation calculation without rigorous justification. A rigorous derivation of Fourier's law for heat conduction from the laws of mechanics remains thus a major unsolved problem. In this note we present a deterministic mechanical model of a heat-conducting chain with nontrivial interactions, where kinetic energy fluctuations at the nodes of the chain are removed. In this model the derivation of Fourier's law can proceed rigorously.

David Ruelle

2011-02-27T23:59:59.000Z

172

Thin?film conducting microgrids as transparent heat mirrors  

Science Conference Proceedings (OSTI)

A new type of transparent heat mirror for solar?energy applications has been fabricated by chemically etching a Sn?doped In2O3 film to form a transparent conducting microgrid. For square openings 2.5 ?m on a side

John C. C. Fan; Frank J. Bachner; R. A. Murphy

1976-01-01T23:59:59.000Z

173

Duct Systems in large commercial buildings: Physical characterization, air leakage, and heat conduction gains  

E-Print Network (OSTI)

Air Leakage, and Heat Conduction Gains William 1. Fisk,0.75 to 0.90; thus, heat conduction decreased the coolingby air leakage or heat conduction, because these ducts are

Fisk, W.J.

2011-01-01T23:59:59.000Z

174

Thermal conductivity of rocks associated with energy extraction from hot dry rock geothermal systems  

DOE Green Energy (OSTI)

Results of thermal conductivity measurements are given for 14 drill core rock samples taken from two exploratory HDR geothermal wellbores (maximum depth of 2929 m (9608 ft) drilled into Precambrian granitic rock in the Jemez Mountains of northern New Mexico. These samples have been petrographically characterized and in general represent fresh competent Precambrian material of deep origin. Thermal conductivities, modal analyses, and densities are given for all core samples studied under dry and water-saturated conditions. Additional measurements are reported for several sedimentary rocks encountered in the upper 760 m (2500 ft) of that same region. A cut-bar thermal conductivity comparator and a transient needle probe were used for the determinations with fused quartz and Pyroceram 9606 as the standards. The maximum temperature range of the measurements was from the ice point to 250/sup 0/C. The measurements on wet, water-saturated rock were limited to the temperature range below room temperature. Conductivity values of the dense core rock samples were generally within the range from 2 to 2.9 W/mK at 200/sup 0/C. Excellent agreement was achieved between these laboratory measurements of thermal conductivity and those obtained by in situ measurements used in the HDR wellbores. By using samples of sufficient thickness to provide a statistically representative heat flow path, no difference between conductivity values and their temperature coefficients for orthogonal directions (heat flow parallel or perpendicular to core axis) was observed. This isotropic behavior was even found for highly foliated gneissic specimens. Estimates of thermal conductivity based on a composite dispersion analysis utilizing pure minerallic phase conductivities and detailed modal analyses usually agreed to within 9 percent of the experimental values.

Sibbitt, W.L.; Dodson, J.G.; Tester, J.W.

1978-01-01T23:59:59.000Z

175

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

176

Thermal Crosslinking of Organic Semiconducting Polythiophene Improves Transverse Hole Conductivity  

Science Conference Proceedings (OSTI)

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

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

2009-10-26T23:59:59.000Z

177

The effect of thermal aging on the thermal conductivity of plasma sprayed and EB-PVD thermal barrier coatings  

DOE Green Energy (OSTI)

Thermal barrier coatings (TBCs) applied to the hot gas components of turbine engines lead to enhanced fuel efficiency and component reliability. Understanding the mechanisms which control the thermal transport behavior of the TBCs is of primary importance. Electron beam-physical vapor deposition (EV-PVD) and air plasma spraying (APS) are the two most commonly used coating techniques. These techniques produce coatings with unique microstructures which control their performance and stability. The density of the APS coatings was controlled by varying the spray parameters. The low density APS yttria-partially stabilized zirconia (yttria-PSZ) coatings yielded a thermal conductivity that is lower than both the high density APS coatings and the EB-PVD coatings. The thermal aging of both fully and partially stabilized zirconia are compared. The thermal conductivity of the coatings permanently increases upon exposure to high temperatures. These increases are attributed to microstructural changes within the coatings. This increase in thermal conductivity can be modeled using a relationship which depends on both the temperature and time of exposure. Although the EB-PVD coatings are less susceptible to thermal aging effects, results suggest that they typically have a higher thermal conductivity than APS coatings before thermal aging. The increases in thermal conductivity due to thermal aging for plasma sprayed partially stabilized zirconia have been found to be less than for plasma sprayed fully stabilized zirconia coatings.

Dinwiddie, R.B.; Beecher, S.C.; Porter, W.D. [Oak Ridge National Lab., TN (United States); Nagaraj, B.A. [General Electric Co., Cincinnati, OH (United States). Aircraft Engine Group

1996-05-01T23:59:59.000Z

178

Ion thermal conductivity for a pure tokamak plasma  

DOE Green Energy (OSTI)

The neoclassical and Pfirsch-Schlueter component of the ion heat conduction for a pure hydrogen Tokamak plasma are recalculated without assuming large aspect ratio and without neglecting energy scattering collisions. Using a model collision operator the conductivity is determined numerically for various collision frequencies and aspect ratios. An approximate algebraic expression is fitted to the results. Even for comparatively large aspect ratios(approx. 10) energy scattering increases the conductivity in the banana regime by about 50% and for small aspect ratios(approx. 3.3) the Pfirsch-Schlueter contribution causes a further increase of approximately 60%.

Bolton, C.; Ware, A.

1981-10-01T23:59:59.000Z

179

Two-Gradient Convection in a Vertical Slot with Maxwell-Cattaneo Heat Conduction  

SciTech Connect

We study the effect of the Maxwell-Cattaneo law of heat conduction (MCHC) on the 1D flow in a vertical slot subject to both vertical and horizontal temperature gradients. The gravitational acceleration is allowed to oscillate, which provides an opportunity to investigate the quantitative contribution of thermal inertia as epitomized by MCHC. The addition of the time derivative in MCHC increases the order of the system. We use a spectral expansion with Rayleigh's beam functions as the basis set, which is especially suited to fourth order boundary value problems (BVP). We show that the time derivative (relaxation of the thermal flux) has a dissipative nature and leads to the appearance of purely real negative eigenvalues. Yet it also increases the absolute value of the imaginary part and decreases the absolute value of the real part of the complex eigenvalues. Thus, the system has a somewhat more oscillatory behavior than the one based on Fourier's heat conduction law (FHC)

Papanicolaou, N. C. [Department of Computer Science, University of Nicosia, P.O. Box 24005, 1700 Nicosia (Cyprus); Christov, C. I. [Department of Mathematics, University of Louisiana at Lafayette, LA 70504-1010 (United States); Jordan, P. M. [Entropy Reversal Consultants (L.L.C), P. O. Box 691, Abita Springs, LA 70420 (United States); Code 7181, Naval Research Lab., Stennis Space Ctr., MS 39529 (United States)

2009-10-29T23:59:59.000Z

180

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

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181

Conduction Effect of Thermal Radiation in a Metal Shield Pipe in a Cryostat for a Cryogenic Interferometric Gravitational Wave Detector  

E-Print Network (OSTI)

A large heat load caused by thermal radiation through a metal shield pipe was observed in a cooling test of a cryostat for a prototype of a cryogenic interferometric gravitational wave detector. The heat load was approximately 1000 times larger than the value calculated by the Stefan-Boltzmann law. We studied this phenomenon by simulation and experiment and found that it was caused by the conduction of thermal radiation in a metal shield pipe.

Takayuki Tomaru; Masao Tokunari; Kazuaki Kuroda; Takashi Uchiyama; Akira Okutomi; Masatake Ohashi; Hiroyuki Kirihara; Nobuhiro Kimura; Yoshio Saito; Nobuaki Sato; Takakazu Shintomi; Toshikazu Suzuki; Tomiyoshi Haruyama; Shinji Miyoki; Kazuhiro Yamamoto; Akira Yamamoto

2007-11-06T23:59:59.000Z

182

IMPROVING THERMAL PERFORMANCE OF RADIOACTIVE MATERIAL DRUM TYPEPACKAGES BY USING HEAT PIPES  

Science Conference Proceedings (OSTI)

This paper presents a feasibility study to improve thermal loading of existing radioactive material packages by using heat pipes. The concept could be used to channel heat in certain directions and dissipate to the environment. The concept is applied to a drum type package because the drum type packages are stored and transported in an upright position. This orientation is suitable for heat pipe operation that could facilitate the heat pipe implementation in the existing well proven package designs or in new designs where thermal loading is high. In this position, heat pipes utilize gravity very effectively to enhance heat flow in the upward direction Heat pipes have extremely high effective thermal conductivity that is several magnitudes higher than the most heat conducting metals. In addition, heat pipes are highly unidirectional so that the effective conductivity for heat transfer in the reverse direction is greatly reduced. The concept is applied to the 9977 package that is currently going through the DOE certification review. The paper presents computer simulations using typical off-the-shelf heat pipe available configurations and performance data for the 9977 package. A path forward is outlined for implementing the concepts for further study and prototype testing.

Gupta, N

2007-03-06T23:59:59.000Z

183

Thermal Storage and Advanced Heat Transfer Fluids (Fact Sheet...  

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

Thermophysical Properties In our Thermal Storage Materials Laboratory, we use a variety of instruments to measure the thermophysical properties of heat transfer fluids and storage...

184

Heat flow determinations and implied thermal regime of the Coso...  

Open Energy Info (EERE)

determinations and implied thermal regime of the Coso geothermal area, California Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Conference Proceedings: Heat flow...

185

The Effect of Graphitization Heat Treatment Temperature on Thermal ...  

Science Conference Proceedings (OSTI)

Presentation Title, The Effect of Graphitization Heat Treatment Temperature on Thermal Properties of PAN-Based Carbon Fiber Carbon-Carbon Composites in ...

186

Thermal design of heat exchanger for a swimming pool.  

E-Print Network (OSTI)

??This paper tells about what is a heat exchanger made of in terms of thermal analysis and the important tools and factors which play vital… (more)

Teka, Addisu

2012-01-01T23:59:59.000Z

187

Kinematic Self-Similar Heat Conducting and Charge Solutions  

E-Print Network (OSTI)

The objective of this paper is to study the plane symmetric kinematic self-similar heat conducting fluid and charge dust solutions of the Einstein field equations. These solutions are classified according to self-similarity of the first, second, zeroth and infinite kinds with different equations of state. We take the self-similar vector to be tilted, orthogonal and parallel to the fluid flow. For heat conducting fluid, it is found that there exist only \\emph{one} solution in parallel case. In all other possibilities, these solutions reduce to the perfect fluid kinematic self-similar solutions. For charge dust case, we also obtain only \\emph{one} kinematic self-similar solution.

M. Sharif; Wajiha Javed

2010-12-01T23:59:59.000Z

188

Normal heat conductivity in chains capable of dissociation  

E-Print Network (OSTI)

The paper suggests a resolution for recent controversy over convergence of heat conductivity in one-dimensional chains with asymmetric nearest-neighbor potential. We conjecture that the convergence is promoted not by the mere asymmetry of the potential, but due to ability of the chain to dissociate. In other terms, the attractive part of the potential function should approach a finite value as the distance between the neighbors grows. To clarify this point, we study the simplest model of this sort -- a chain of linearly elastic disks with finite diameter. If the distance between the disk centers exceeds their diameter, the disks cease to interact. Formation of gaps between the disks is the only possible mechanism for scattering of the oscillatory waves. Heat conduction in this system turns out to be convergent. Moreover, an asymptotic behavior of the heat conduction coefficient for the case of large densities and relatively low temperatures obeys simple Arrhenius-type law. In the limit of low densities, the h...

Gendelman, O V

2013-01-01T23:59:59.000Z

189

Fuzzy and interval finite element method for heat conduction problem  

E-Print Network (OSTI)

Traditional finite element method is a well-established method to solve various problems of science and engineering. Different authors have used various methods to solve governing differential equation of heat conduction problem. In this study, heat conduction in a circular rod has been considered which is made up of two different materials viz. aluminum and copper. In earlier studies parameters in the differential equation have been taken as fixed (crisp) numbers which actually may not. Those parameters are found in general by some measurements or experiments. So the material properties are actually uncertain and may be considered to vary in an interval or as fuzzy and in that case complex interval arithmetic or fuzzy arithmetic has to be considered in the analysis. As such the problem is discretized into finite number of elements which depend on interval/fuzzy parameters. Representation of interval/fuzzy numbers may give the clear picture of uncertainty. Hence interval/fuzzy arithmetic is applied in the finite element method to solve a steady state heat conduction problem. Application of fuzzy finite element method in the said problem gives fuzzy system of linear equations in general. Here new methods have also been proposed to handle such type of fuzzy system of linear equations. Corresponding results are computed and has been reported here.

Sarangam Majumdar; Sukanta Nayak; S. Chakraverty

2012-09-26T23:59:59.000Z

190

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

E-Print Network (OSTI)

Modern food processing operations often require that the temperature of the processed foodstuff be raised or lowered. These operations result in energy consumption by refrigeration or heating systems, and a portion of this energy can be recovered from waste heat streams for reuse in the processing operations. This paper addresses the recovery of waste heat and the storage of thermal energy as a means of energy conservation in food processing. An energy conservation project in a poultry processing plant sponsored by the U.S. Department of Energy and conducted by Georgia Tech is used as an illustrative example of potential applications of heat recovery and thermal energy storage.

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

1980-01-01T23:59:59.000Z

191

Atomistic calculation of the thermal conductance of large scale bulk-nanowire junctions  

SciTech Connect

We have developed a stable and efficient kernel method to compute thermal transport in open systems, based on the scattering-matrix approach. This method is applied to compute the thermal conductance of a junction between bulk silicon and silicon nanowires with diameter up to 10 nm. We have found that beyond a threshold diameter of 7 nm, transmission spectra and contact conductances scale with the cross section of the contact surface, whereas deviations from this general trend are observed in thinner wires. This result allows us to predict the thermal resistance of bulk-nanowire interfaces with larger cross sections than those tractable with atomistic simulations, and indicate the characteristic size beyond which atomistic systems can in principle be treated accurately by mean-field theories. Our calculations also elucidate how dimensionality reduction and shape affect interfacial heat transport.

Duchemin, Ivan; Donadio, Davide [Max Planck Institute for Polymer Research, Ackermannweg 10, D-55128 Mainz (Germany)

2011-09-15T23:59:59.000Z

192

COSMOLOGICAL MAGNETOHYDRODYNAMIC SIMULATIONS OF CLUSTER FORMATION WITH ANISOTROPIC THERMAL CONDUCTION  

SciTech Connect

The intracluster medium (ICM) has been suggested to be buoyantly unstable in the presence of magnetic field and anisotropic thermal conduction. We perform first cosmological simulations of galaxy cluster formation that simultaneously include magnetic fields, radiative cooling, and anisotropic thermal conduction. In isolated and idealized cluster models, the magnetothermal instability (MTI) tends to reorient the magnetic fields radially whenever the temperature gradient points in the direction opposite to gravitational acceleration. Using cosmological simulations of cluster formation we detect radial bias in the velocity and magnetic fields. Such radial bias is consistent with either the inhomogeneous radial gas flows due to substructures or residual MTI-driven field rearrangements that are expected even in the presence of turbulence. Although disentangling the two scenarios is challenging, we do not detect excess bias in the runs that include anisotropic thermal conduction. The anisotropy effect is potentially detectable via radio polarization measurements with LOFAR and the Square Kilometer Array and future X-ray spectroscopic studies with the International X-ray Observatory. We demonstrate that radiative cooling boosts the amplification of the magnetic field by about two orders of magnitude beyond what is expected in the non-radiative cases. This effect is caused by the compression of the gas and frozen-in magnetic field as it accumulates in the cluster center. At z = 0 the field is amplified by a factor of about 10{sup 6} compared to the uniform magnetic field that evolved due to the universal expansion alone. Interestingly, the runs that include both radiative cooling and thermal conduction exhibit stronger magnetic field amplification than purely radiative runs. In these cases, buoyant restoring forces depend on the temperature gradients rather than the steeper entropy gradients. Thus, the ICM is more easily mixed and the winding up of the frozen-in magnetic field is more efficient, resulting in stronger magnetic field amplification. We also demonstrate that thermal conduction partially reduces the gas accretion driven by overcooling despite the fact that the effective conductivity is suppressed below the Spitzer-Braginskii value.

Ruszkowski, M. [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States); Lee, D. [Department of Astronomy, ASC/Flash Center, University of Chicago, 5640 South Ellis Avenue, Chicago, IL 60637 (United States); Brueggen, M. [School of Engineering and Science, Jacobs University Bremen, Campus Ring 1, 28759 Bremen 05233 (Germany); Parrish, I. [Astronomy Department and Theoretical Astrophysics Center, 601 Campbell Hall, University of California, Berkeley, CA 94720 (United States); Oh, S. Peng, E-mail: mateuszr@umich.edu, E-mail: dongwook@flash.uchicago.edu, E-mail: m.brueggen@jacobs-university.de, E-mail: iparrish@astro.berkeley.edu, E-mail: peng@physics.ucsb.edu [Department of Physics, University of California, Santa Barbara, CA 93106 (United States)

2011-10-20T23:59:59.000Z

193

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

Science Conference Proceedings (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

Greg C. Glatzmaier; W. Fred Ramirez

1985-01-01T23:59:59.000Z

194

A Multiscale Model for Coupled Heat Conduction and Deformations of Viscoelastic Composites  

E-Print Network (OSTI)

This study introduces a multiscale model for analyzing nonlinear thermo-viscoelastic responses of particulate composites. A simplified micromechanical model consisting of four sub-cells, i.e., one particle and three matrix sub-cells is formulated to obtain the effective thermal and mechanical properties and time-dependent response of the composites. The particle and matrix constituents are made of isotropic homogeneous viscoelastic bodies undergoing small deformation gradients. Perfect bonds are assumed along the sub-cell???s interfaces. The coupling between the thermal and mechanical response is attributed to the dissipation of energy due to the viscoelastic deformation and temperature dependent material parameters in the viscoelastic constitutive model. The micromechanical relations are formulated in terms of incremental average field quantities, i.e., stress, strain, heat flux and temperature gradient, in the sub-cells. The effective mechanical properties and coefficient of thermal expansion are derived by satisfying displacement- and traction continuities at the interfaces during the thermo-viscoelastic deformations. The effective thermal conductivity is formulated by imposing heat flux- and temperature continuities at the subcells??? interfaces. The expression of the effective specific heat at a constant stress is also established. A time integration algorithm for simultaneously solving the equations that govern heat conduction and thermoviscoelastic deformations of isotropic materials is developed. The algorithm is then incorporated within each sub-cell of the micromechanical model together with the macroscopic energy equation to determine the effective coupled thermoviscoelastic response of the particulate composite. The numerical formulation is implemented within the ABAQUS, general purpose displacement based FE software, allowing for analyzing coupled heat conduction and deformations of composite structures. Experimental data on the effective thermal properties and time dependent responses of particulate composites available in the literature are used to verify the micromechanical model formulation. The multiscale model capability is also examined by comparing the field variables, i.e., temperature, displacement, stresses and strains, obtained from heterogeneous and homogeneous composite structures, during the transient heat conduction and deformations. Examples of coupled thermoviscoelastic analyses of particulate composites and functionally graded structures are also presented. The present micromechanical modeling approach is found to be computationally efficient and shows good agreement with experiments in predicting the effective thermo-mechanical response of particulate composites and functionally graded materials. Our analyses forecast a better design for creep resistant and less dissipative structures using particulate composites and functionally graded materials.

Khan, Kamran Ahmed

2011-05-01T23:59:59.000Z

195

THERMAL CONDUCTIVITY AND VISCOSITY OF GAS MIXTURES (thesis)  

SciTech Connect

Correlations based upon empirical modified equations derived from kinetic theory were developed for the thermal conductivity and viscosity of gas mixtures. The conductivity equation was compared to 226 binary mixture conductivities in temperatures from 0 to 774 deg C from the literature and this work. The average deviation is 2.1%. In correlating conductivity data of mixtures of polyatomic molecules, the energy transport is considered in two parts, i.e., one protion transferred by collision and the other by diffusion. The proposed viscosity equation reproduces 103 binary data points with an average deviation of 1.3%. These equations are more consistent with experiment than existing correlations in the literature. the relation of the conductivity or viscosity to composition and temperature are discussed in the light of the proposed equations. It has been demonstrated that, at a given composition, the ratio of the measured conductivity to that calculated on the molar average basis for mixtures of most simple molecules and the ratio of the measured viscosity to that calculated on the molar average basis for mixtures of most gases should be nearly constant over a temperature range of 200 to 300 deg C. The thermal conductivity of ten gases and selected binary and ternary mixtures of them were measured in a concentric silver cylinder cell in the temperature range of 100 to 540 deg C The gases are He, A, N/sub 2/, O/sub 2/, CO/sub 2/, CH/sub 4/, C/sub 2/ H/sub 4/, C/sub 3/H/sub 8/, methyl ether , and methyl formats. (auth)

Cheung, H.

1958-04-01T23:59:59.000Z

196

MHD Simulations of a Moving Subclump with Heat Conduction  

E-Print Network (OSTI)

High resolution observations of cluster of galaxies by Chandra have revealed the existence of an X-ray emitting comet-like galaxy C153 in the core of cluster of galaxies A2125. The galaxy C153 moving fast in the cluster core has a distinct X-ray tail on one side, obviously due to ram pressure stripping, since the galaxy C153 crossed the central region of A2125. The X-ray emitting plasma in the tail is substantially cooler than the ambient plasma. We present results of two-dimensional magnetohydrodynamic simulations of the time evolution of a subclump like C153 moving in magnetized intergalactic matter. Anisotropic heat conduction is included. We found that the magnetic fields are essential for the existence of the cool X-ray tail, because in non-magnetized plasma the cooler subclump tail is heated up by isotropic heat conduction from the hot ambient plasma and does not form such a comet-like tail.

Naoki Asai; Naoya Fukuda; Ryoji Matsumoto

2004-12-15T23:59:59.000Z

197

THE EFFECT OF ANISOTROPIC CONDUCTION ON THE THERMAL INSTABILITY IN THE INTERSTELLAR MEDIUM  

SciTech Connect

Thermal instability (TI) can strongly affect the structure and dynamics of the interstellar medium (ISM) in the Milky Way and other disk galaxies. Thermal conduction plays an important role in the TI by stabilizing small scales and limiting the size of the smallest condensates. In the magnetized ISM, however, heat is conducted anisotropically (primarily along magnetic field lines). We investigate the effects of anisotropic thermal conduction on the nonlinear regime of the TI by performing two-dimensional magnetohydrodynamic simulations. We present models with magnetic fields of different initial geometries and strengths, and compare them to hydrodynamic models with isotropic conduction. We find that anisotropic conduction does not significantly alter the overall density and temperature statistics in the saturated state of the TI. However, it can strongly affect the shapes and sizes of cold clouds formed by the TI. For example, for uniform initial fields long filaments of cold gas are produced that are reminiscent of some observed H I clouds. For initially tangled fields, such filaments are not produced. We also show that anisotropic conduction suppresses turbulence generated by evaporative flows from the surfaces of cold blobs, which may have implications for mechanisms for driving turbulence in the ISM.

Choi, Ena; Stone, James M. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States)

2012-03-10T23:59:59.000Z

198

Aircraft Thermal Management Using Loop Heat Pipes.  

E-Print Network (OSTI)

??The objective of this thesis was to determine the feasibility of using loop heat pipes to dissipate waste heat from power electronics to the skin… (more)

Fleming, Andrew J.

2009-01-01T23:59:59.000Z

199

Temperature distribution of a tokamak with a constant heat conductivity  

SciTech Connect

An analytical expression of the detached plasma radius in and ohmically heated tokamak plasma was obtained. The assumption was made that the (anomalous) heat conductivity is constant and independent of minor radius, r. The resultant nonlinear differential equation has a universal solution for the plasma temperature as a function of r. The shape is very similar to the so-called profile consistency model. As the average plasma density increases, the tokamak plasma which is first attached to either limiter or divertor detaches itself from the limiter and forms a toroidal plasma whose boundary is clearly marked by a radiative boundary layer where the power input to the plasma is radiated away. As the plasma density increases, the radius of the plasma shrinks until the surface safety factor becomes less that {approximately}2, whereupon the plasma disruption starts. The density limit calculated by this model agrees with the experimental observation. 1 ref., 1 fig., 1 tab.

Yoshikawa, S.

1990-05-01T23:59:59.000Z

200

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

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

Tree-Shaped Fluid Flow and Heat Storage in a Conducting Solid  

Science Conference Proceedings (OSTI)

This paper documents the time-dependent thermal interaction between a fluid stream configured as a plane tree of varying complexity embedded in a conducting solid with finite volume and insulated boundaries. The time scales of the convection-conduction phenomenon are identified. Two-dimensional and three-dimensional configurations are simulated numerically. The number of length scales of the tree architecture varies from one to four. The results show that the heat transfer density increases, and the time of approach to equilibrium decreases as the complexity of the tree designs increases. These results are then formulated in the classical notation of energy storage by sensible heating, which shows that the effective number of heat transfer units increases as the complexity of the tree design increases. The complexity of heat transfer designs in many applications is constrained by first cost and operating cost considerations. This work provides a fundamental basis for objective evaluation of cost and performance tradeoffs in thermal design of energy systems with complexity as an unconstrained parameter that can be actively varied over a broad range to determine the optimum system design.

Combelles, L.; Lorente, S.; Anderson, R.; Bejan, A.

2012-01-01T23:59:59.000Z

202

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

203

Modelling the vertical heat exchanger in thermal basin  

Science Conference Proceedings (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

204

Tunable single-photon heat conduction in electrical circuits  

E-Print Network (OSTI)

We build on the study of single-photon heat conduction in electronic circuits taking into account the back-action of the superconductor--insulator--normal-metal thermometers. In addition, we show that placing capacitors, resistors, and superconducting quantum interference devices (SQUIDs) into a microwave cavity can severely distort the spatial current profile which, in general, should be accounted for in circuit design. The introduction of SQUIDs also allows for in situ tuning of the photonic power transfer which could be utilized in experiments on superconducting quantum bits.

P. J. Jones; J. A. M. Huhtamäki; M. Partanen; K. Y. Tan; M. Möttönen

2012-05-21T23:59:59.000Z

205

AdS/CFT Correspondence with Heat Conduction  

E-Print Network (OSTI)

We study an extension of the gravity dual to a perfect fluid model found by Janik and Peschanski. By relaxing one of the constraints, namely invariance under reflection in the longitudinal direction, we introduce a metric ansatz which includes off-diagonal terms. We also include an $R$-charge following Bak and Janik. We solve the Maxwell-Einstein equations and through holographic renormalization, we show that the off-diagonal components of the bulk metric give rise to heat conduction in the corresponding CFT on the boundary.

James Alsup; Chad Middleton; George Siopsis

2006-07-20T23:59:59.000Z

206

Effective Thermal Conductivity of High Temperature Insulations for Reusable Launch Vehicles  

E-Print Network (OSTI)

An experimental apparatus was designed to measure the effective thermal conductivity of various high temperature insulations subject to large temperature gradients representative of typical launch vehicle reentry aerodynamic heating conditions. The insulation sample cold side was maintained around room temperature, while the hot side was heated to temperatures as high as 1800°F. The environmental pressure was varied from 1 x 10 -4 to 760 torr. All the measurements were performed in a dry gaseous nitrogen environment. The effective thermal conductivity of the following insulation samples were measured: Saffilä at 1.5, 3, 6 lb/ft 3 , Q-Fiberä felt at 3, 6 lb/ft 3 , Cerachromeä at 6, 12 lb/ft 3 , and three multi-layer insulation configurations at 1.5 and 3 lb/ft 3 .. Introduction Metallic and refractory-composite thermal protection systems are being considered for a new generation of reusable launch vehicles (RLV). The main function of the thermal protection system (TPS) is to...

Kamran Daryabeigi

1999-01-01T23:59:59.000Z

207

Effective Thermal Conductivity of High Temperature Insulations for Reusable Launch Vehicles  

E-Print Network (OSTI)

An experimental apparatus was designed to measure the effective thermal conductivity of various high temperature insulations subject to large temperature gradients representative of typical launch vehicle reentry aerodynamic heating conditions. The insulation sample cold side was maintained around room temperature, while the hot side was heated to temperatures as high as 1800F. The environmental pressure was varied from 1 x 10 -4 to 760 torr. All the measurements were performed in a dry gaseous nitrogen environment. The effective thermal conductivity of the following insulation samples were measured: Saffil at 1.5, 3, 6 lb/ft 3 , Q-Fiber felt at 3, 6 lb/ft 3 , Cerachrome at 6, 12 lb/ft 3 , and three multi-layer insulation configurations at 1.5 and 3 lb/ft 3 .. Introduction Metallic and refractory-composite thermal protection systems are being considered for a new generation of reusable launch vehicles (RLV). The main function of the thermal protection system (TPS) is to mai...

Kamran Daryabeigi Langley

1999-01-01T23:59:59.000Z

208

Experimental and numerical study of the effective thermal conductivity of silica nanocomposites with thermal boundary resistance  

SciTech Connect

The thermal interface resistance at the macro scale is mainly described by the physical gap between two interfaces and constriction resistance due to this gap. The small gaps between the two material faces makes up the majority of thermal interface resistance at the macro scale. So, most of the studies have been focused on characterizing effect of surface geometry and material properties to thermal interface resistance. This resistance is more widely known as thermal contact resistance, represented with Rc. There are various models to predict thermal contact resistance at macro scale. These models predict thermal resistance Rc for given two materials by utilizing their bulk thermomechanical properties. Although, Rc represents thermal resistance accurately for macro size contacts between two metals, it is not suitable to describe interface resistance of particles in modern TIMs, aka particulate composites. The particles inside recently available TIMs are micron size and with effort to further increase surface area this particle size is approaching nano scale. At this small scale, Rc does not accurately predict thermal interface, as it is very difficult to characterize the surface topography. The thermal discontinuity at perfectly bonded interface of two dissimilar materials is termed as thermal boundary resistance (Rb) or Kapitza resistance. The macroscopic assumptions that thermal discontinuity only exists due to gaps and surface geometry leads to substantial error in determining interface thermal properties at micron and nano scale. The phenomenon of thermal boundary resistance is an inherent material property and arises due to fundamental mechanism of thermal transport. For metal-matrix particulate composites, Rb plays more important role than Rc. The free flowing nature of the polymer would eliminate most of the gaps between the two materials at their interface. This means almost all of the thermal resistance at particle/matrix interface would occur due to Rb. The current study presents experimental study of thermal boundary resistance for silica nano particles embedded inside epoxy resin. The bulk conductivity of the sample is measured and Rc is back calculated using Hasselman-Johnson s (H-J) equation. The numerical validation of the equation is also presented, including extrapolation study to predict effective conductivity of the nanocomposite TIM.

Kothari, Rushabh M [ORNL; Dinwiddie, Ralph Barton [ORNL; Wang, Hsin [ORNL

2013-01-01T23:59:59.000Z

209

Electrical conductivity and thermal dilepton rate from quenched lattice QCD  

E-Print Network (OSTI)

We report on a continuum extrapolation of the vector current correlation function for light valence quarks in the deconfined phase of quenched QCD. This is achieved by performing a systematic analysis of the influence of cut-off effects on light quark meson correlators at $T\\simeq 1.45 T_c$ using clover improved Wilson fermions. We discuss resulting constraints on the electrical conductivity and the thermal dilepton rate in a quark gluon plasma. In addition new results at 1.2 and 3.0 $T_c$ will be presented.

Olaf Kaczmarek; Anthony Francis

2011-09-19T23:59:59.000Z

210

Electrical conductivity and thermal dilepton rate from quenched lattice QCD  

E-Print Network (OSTI)

We report on a continuum extrapolation of the vector current correlation function for light valence quarks in the deconfined phase of quenched QCD. This is achieved by performing a systematic analysis of the influence of cut-off effects on light quark meson correlators at $T\\simeq 1.45 T_c$ using clover improved Wilson fermions. We discuss resulting constraints on the electrical conductivity and the thermal dilepton rate in a quark gluon plasma. In addition new results at 1.2 and 3.0 $T_c$ will be presented.

Kaczmarek, Olaf

2011-01-01T23:59:59.000Z

211

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

212

Thermal Performance Predictions of a Heat Pipe and Heat Dissipation Systems Using FEM.  

E-Print Network (OSTI)

??The aim of this work is to carry out analyses, thermal and fluid dynamics of element used to heat transimission that can be utilized to… (more)

VIGNA, GIUSEPPE

2008-01-01T23:59:59.000Z

213

Measurement of effective thermal conductivity of wheat as a function of moisture content  

Science Conference Proceedings (OSTI)

Grain drying and storage are one of the main activities of agricultural industry. Increasing energy costs have stressed the importance of calculation of heat and mass transfer in a grain bulk in order to be able to optimize drying facilities. Another limitation during drying is the preservation of grain structure and its nutritional values, Muehlbauer and Christ have shown that damage to the grain structure and grain nutritional value is dependent upon grain temperature and drying time. Therefore, proper conditions during drying and storage of cereal grains require the knowledge of the thermophysical properties of the grains. The effective thermal conductivity of two varieties of Triticum durum wheat and a wheat product, bulgur, is determined at different moisture contents and at ambient temperature by the transient lime heat source method. The moisture contents of the samples ranged from 9.17 to 38.65% wet basis and the bulk densities ranged from 675 to 827 kg/m{sup 3}. Under those conditions, the measured effective thermal conductivities ranged from 0.159 to 0.201 W/m.K. The effective thermal conductivity is found to be linearly increasing with moisture content. The results are also in good agreement with literature values.

Tavman, S. [Ege Univ., Izmir (Turkey). Food Engineering Dept.] [Ege Univ., Izmir (Turkey). Food Engineering Dept.; Tavman, I.H. [Dokuz Eyluel Univ., Izmir (Turkey). Mechanical Engineering Dept.] [Dokuz Eyluel Univ., Izmir (Turkey). Mechanical Engineering Dept.

1998-07-01T23:59:59.000Z

214

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

Science Conference Proceedings (OSTI)

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

215

Experimental investigation on the photovoltaic-thermal solar heat pump air-conditioning system on water-heating mode  

Science Conference Proceedings (OSTI)

An experimental study on operation performance of photovoltaic-thermal solar heat pump air-conditioning system was conducted in this paper. The experimental system of photovoltaic-thermal solar heat pump air-conditioning system was set up. The performance parameters such as the evaporation pressure, the condensation pressure and the coefficient of performance (COP) of heat pump air-conditioning system, the water temperature and receiving heat capacity in water heater, the photovoltaic (PV) module temperature and the photovoltaic efficiency were investigated. The experimental results show that the mean photovoltaic efficiency of photovoltaic-thermal (PV/T) solar heat pump air-conditioning system reaches 10.4%, and can improve 23.8% in comparison with that of the conventional photovoltaic module, the mean COP of heat pump air-conditioning system may attain 2.88 and the water temperature in water heater can increase to 42 C. These results indicate that the photovoltaic-thermal solar heat pump air-conditioning system has better performances and can stably work. (author)

Fang, Guiyin; Hu, Hainan; Liu, Xu [Department of Physics, Nanjing University, Nanjing 210093 (China)

2010-09-15T23:59:59.000Z

216

Heat pipe thermal control of irradiation capsules  

SciTech Connect

From 1st international heat pipe conference; Stuttgart, F.R. Germany (15 Oct 1973). The use of heat pipes to control the temperature of irradiation capsules containing fast breeder reactor structural materials is discussed. (TFD)

Deverall, J.E.

1974-04-30T23:59:59.000Z

217

NOTES ON THERMAL PROPERTIES AND HEAT TRANSFER OF SYNTACTIC FOAM SUBSEA INSULATION  

E-Print Network (OSTI)

1. The properties that make syntactic foam an efficient buoyancy material also make it a good subsea thermal insulator: low density, high strength, and resistance to water penetration. The hollow spherical fillers in the foam contain air and prevent its compres-sion by hydrostatic force. The air in turn acts as a very effective insulator, slowing heat transfer as long as structural integrity is maintained. 2. Heat transfer textbooks list three modes of heat transfer: conduction, convection, and radiation. Radiation is seldom a factor in “wet ” subsea insulation, and convection plays a role only when water is free to circulate, a condition normally avoided. Therefore, this paper focuses on conduction as the principal way in which heat travels through syntactic foam insulation. 3. A glossary of heat transfer properties is given on Page 4. The following definitions apply to the terms we will be using most frequently: Density: Mass per unit volume is symbolized by the Greek letter rho (_); it is usually numerically equivalent to weight per unit volume, but caution is required to make sure the correct values are always used. Thermal Conductivity: The rate at which heat is conducted through the material in question. The higher the conductivity (k-value), the more easily heat will be transmitted from the “hot ” to the

Lou Watkins

2003-01-01T23:59:59.000Z

218

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

E-Print Network (OSTI)

Continued development of highly compact and powerful electronic components has led to the need for a simple and effective method for controlling the thermal characteristics of these devices. One proposed method for thermal control involves the use 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. To further explore this possibility, a design scenario with appropriate constraints was established and a model developed to solve for the effective thermal conductance of individual heat pipes as a function of evaporator-end temperature. From the results of this analysis, several working fluids were identified and selected from a list over thirteen hundred that were initially analyzed. Next, a thermal circuit model was developed that translated the individual heat pipe operating characteristics into the system as a whole to determine the system level effects. It was found that none of the prospective fluids could completely satisfy the established design requirements to regulate the device temperature over the entire range of operating conditions. This failure to fully satisfy design requirements was due, in large part, to the highly constrained nature of problem definition. Several fluids, however, did provide for an improved level of thermal control when compared to the unmodified design. Suggestions for improvements that may lead to enhanced levels of thermal control are offered as well as areas that are in need of further research.

Coughlin, Scott Joseph

2005-12-01T23:59:59.000Z

219

THE ROLE OF HEAT CONDUCTION IN LEADING EDGE HEATING THEORY AND EXPERIMENT  

E-Print Network (OSTI)

The effect of heat conduction of material on the temperature distribution in the vicinity of a wing leading edge in hypersonic flight is investigated. The theory is based on a conducting plate subjected to aerodynamic heating. It is found that the role played by the conductivity of the materiel and the leading edge thickness in moderating the nose temperature is very significant. Detailed discussions of the numerical solutions for various shapes of leading edge era given. An experimental technique has been developed by which a number of models representing a wing leading edge oan be tested and the results thus obtained are compared with those predicted by the theory. * Replgces A.R.C.31 445-2-

T. Nonweiler; B. Sc, Ph.D.; H. Y. Wong; B. Sc, Ph.D.; S. R. Aggarwal; B. Sc; Price S Od [p; T. Nonweiler; B. Sc, Ph.D.; H. Y. Wang; B. Sc, Ph.D.; S. R. Aggarwal

1969-01-01T23:59:59.000Z

220

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.


221

Light beam dynamics in materials with radially-inhomogeneous thermal conductivity  

E-Print Network (OSTI)

We study the properties of bright and vortex solitons in thermal media with nonuniform thermal conductivity and homogeneous refractive index, whereby the local modulation of the thermal conductivity strongly affects the entire refractive index distribution. While regions where the thermal conductivity is increased effectively expel light, self-trapping may occur in the regions with reduced thermal conductivity, even if such regions are located close to the material boundary. As a result, strongly asymmetric self-trapped beams may form inside a ring with reduced thermal conductivity and perform persistent rotary motion. Also, such rings are shown to support stable vortex solitons, which may feature strongly non-canonical shapes.

Kartashov, Yaroslav V; Torner, Lluis

2013-01-01T23:59:59.000Z

222

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

223

Thermal interface conductance in Si/Ge superlattices by equilibrium molecular dynamics  

E-Print Network (OSTI)

We provide a derivation allowing the calculation of thermal conductance at interfaces by equilibrium molecular dynamics simulations and illustrate our approach by studying thermal conduction mechanisms in Si/Ge superlattices. ...

Esfarjani, Keivan

224

Thermally Activated Desiccant Technology for Heat Recovery and Comfort  

DOE Green Energy (OSTI)

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

225

Distributed Solar-Thermal Combined Heat and Power  

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

Distributed Solar-Thermal Combined Heat and Power Speaker(s): Zack Norwood Date: February 22, 2007 - 12:00pm Location: 90-3122 This seminar will examine the potential for the mild...

226

High Operating Temperature Heat Transfer Fluids for Solar Thermal...  

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

Heat Transfer Fluids for Solar Thermal Power Generation UCLA, UCB, Yale Award Number: DE-EE0005941 | January 9, 2013 | Sungtaek Ju 1.1 Thermochemistry modeling Identified promising...

227

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-

228

Waste heat recovery system having thermal sleeve support for heat pipe  

SciTech Connect

A system for recovering waste heat from a stream of heated gas is disclosed. The system includes a convection heat transfer chamber, a boiler tank, and a plurality of heat pipes thermally interconnecting the convection heat transfer chamber with the boiler tank. Each of the heat pipes includes an evaporator section which is disposed in heat transfer relation with a stream of heated gas flowing through the convection heat transfer chamber, and a condenser section disposed in heat transfer relation with a volume of water contained within the boiler tank. The boiler tank is provided with a header plate having an array of heat pipe openings through which the heat pipes project. A heat pipe support sleeve is received in each heat pipe opening in sealed engagement with the header plate, with the heat pipes projecting through the support sleeves and thermally interconnecting the convection heat transfer chamber with the boiler tank. An intermediate portion of each heat pipe is received in sealed engagement with its associated support sleeve. In a preferred embodiment, heat transfer through the support sleeve is minimized in an arrangement in which each heat pipe opening is reduced by a stepped bore with the support sleeve connected in threaded, sealed engagement with the stepped bore. Futhermore, in this arrangement, the support sleeve has swaged end portions which project beyond the header plate and engage the heat pipe on opposite sides at points which are remote with respect to the support sleeve/header plate interface. One of the swages end portions is sealed against the heat pipe in a fluid-tight union within the boiler tank. The support sleeve is radially spaced with respect to the heat pipe, and is also radially spaced with respect to the heat pipe opening whereby heat transfer through the walls of the heat pipe to the support sleeve and to the header plate is minimized by concentric annular air gaps.

McCurley, J.

1984-01-24T23:59:59.000Z

229

Waste heat recovery system having thermal sleeve support for heat pipe  

SciTech Connect

A system for recovering waste heat from a stream of heated gas is disclosed. The system includes a convection heat transfer chamber, a boiler tank, and a plurality of heat pipes thermally interconnecting the convection heat transfer chamber with the boiler tank. Each of the heat pipes includes an evaporator section which is disposed in heat transfer relation with a stream of heated gas flowing through the convection heat transfer chamber, and a condenser section disposed in heat transfer relation with a volume of water contained within the boiler tank. The boiler tank is provided with a header plate having an array of heat pipe openings through which the heat pipes project. A heat pipe support sleeve is received in each heat pipe opening in sealed engagement with the header plate, with the heat pipes projecting through the support sleeves and thermally interconnecting the convection heat transfer chamber with the boiler tank. An intermediate portion of each heat pipe is received in sealed engagement with its associated support sleeve. In a preferred embodiment, heat transfer through the support sleeve is minimized in an arrangement in which each heat pipe opening is reduced by a stepped bore with the support sleeve connected in threaded, sealed engagement with the stepped bore. Furthermore, in this arrangement, the support sleeve has swaged end portions which project beyond the header plate and engage the heat pipe on opposite sides at points which are remote with respect to the support sleeve/header plate interface. One of the swaged end portions is sealed against the heat pipe in a fluid-tight union within the boiler tank. The support sleeve is radially spaced with respect to the heat pipe, and is also radially spaced with respect to the heat pipe opening whereby heat transfer through the walls of the heat pipe to the support sleeve and to the header plate is minimized by concentric annular air gaps.

McCurley, J.

1984-04-10T23:59:59.000Z

230

Waste heat recovery system having thermal sleeve support for heat pipe  

SciTech Connect

A system for recovering waste heat from a stream of heated gas is disclosed. The system includes a convection heat transfer chamber, a boiler tank, and a plurality of heat pipes thermally interconnecting the convection heat transfer chamber with the boiler tank. Each of the heat pipes includes an evaporator section which is disposed in heat transfer relation with a stream of heated gas flowing through the convection heat transfer chamber, and a condenser section disposed in heat transfer relation with a volume of water contained within the boiler tank. The boiler tank is provided with a header plate having an array of heat pipe openings through which the heat pipes project. A heat pipe support sleeve is received in each heat pipe opening in sealed engagement with the header plate, with the heat pipes projecting through the support sleeves and thermally interconnecting the convection heat transfer chamber with the boiler tank. An intermediate portion of each heat pipe is received in sealed engagement with its associated support sleeve. In a preferred embodiment, heat transfer through the support sleeve is minimized in an arrangement in which each heat pipe opening is reduced by a stepped bore with the support sleeve connected in threaded, sealed engagement with the stepped bore. Furthermore, in this arrangement, the support sleeve has swaged end portions which project beyond the header plate and engage the heat pipe on opposite sides at points which are remote with respect to the support sleeve/header plate interface. One of the swaged end portions is sealed against the heat pipe in a fluid-tight union within the boiler tank. The support sleeve is radially spaced with respect to the heat pipe and is also radially spaced with respect to the heat pipe opening whereby heat transfer through the walls of the heat pipe to the support sleeve and to the header plate is minimized by concentric annular air gaps.

McCurley, J.

1984-12-04T23:59:59.000Z

231

Waste heat recovery system having thermal sleeve support for heat pipe  

SciTech Connect

A system for recovering waste heat from a stream of heated gas is disclosed. The system includes a convection heat transfer chamber, a boiler tank, and a plurality of heat pipes thermally interconnecting the convection heat transfer chamber with the boiler tank. Each of the heat pipes includes an evaporator section which is disposed in heat transfer relation with a stream of heated gas flowing through the convection heat transfer chamber, and a condenser section disposed in heat transfer relation with a volume of water contained within the boiler tank. The boiler tank is provided with a header plate having an array of heat pipe openings through which the heat pipes project. A heat support sleeve is received in each heat pipe opening in sealed engagement with the header plate, with the heat pipes projecting through the support sleeves and thermally interconnecting the convection heat transfer chamber with the boiler tank. An intermediate portion of each heat pipe is received in sealed engagement with its associated support sleeve. In a preferred embodiment, heat transfer through the support sleeve is minimized in an arrangement in which each heat pipe opening is reduced by a stepped bore with the support sleeve connected in threaded, sealed engagement with the stepped bore. Furthermore, in this arrangement, the support sleeve has swaged end portions which project beyond the header plate and engage the heat pipe on opposite sides at points which are remote with respect to the support sleeve/header plate interface. One of the swaged end portions is sealed against the heat pipe in a fluid-tight union within the boiler tank. The support sleeve is radially spaced with respect to the heat pipe, and is also radially spaced with respect to the heat pipe opening whereby heat transfer through the walls of the heat pipe to the support sleeve and to the header plate is minimized by concentric annular air gaps.

McCurley, J.

1984-12-18T23:59:59.000Z

232

Heat pipe thermal control of slender optics probes  

SciTech Connect

The thermal design for a stereographic viewing system is presented. The design incorporates an annular heat pipe and thermal isolation techniques. Test results are compared with design predictions for a prototype configuration. Test data obtained during heat pipe startup showing temperature gradients along the evaporator wall are presented. Correlations relating maximum wall temperature differences to a liquid Reynolds number were obtained at low power levels. These results are compared with Nusselt's Falling Film theory.

Prenger, F.C.

1979-01-01T23:59:59.000Z

233

Thermal Solar Energy Systems for Space Heating of Buildings  

E-Print Network (OSTI)

In this study, the simulation and the analysis of a solar flat plate collectors combined with a compression heat pump is carried out. The system suggested must ensure the heating of a building without the recourse to an auxiliary energy source in complement of this heating system. The system is used to heat a building using heating floor. The building considered is located in Constantine-East of Algeria (Latitude 36.28 N, Longitude 6.62 E, Altitude 689m). For the calculation, the month of February was chosen, which is considered as the coldest month according to the weather data of Constantine. The performances of this system were compared to the performances of the traditional solar heating system using solar collectors and an auxiliary heating load 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 combined with heat pump improve the thermal performance of the heat pump and the global system. The performances of the heating system combining heat pump and solar collectors are higher than that of solar heating system with solar collectors and storage tank. The heat pump assisted by solar energy can contribute to the conservation of conventional energy and can be competitive with the traditional systems of heating.

Gomri, R.; Boulkamh, M.

2010-01-01T23:59:59.000Z

234

EFFECT OF HEAT TREATMENT ON THERMAL PROPERTIES OF PITCH-BASED AND PAN-BASED CARBON-CARBON COMPOSITES  

Science Conference Proceedings (OSTI)

Thermal properties of two directional (2D) pitch-based carbon fiber with charred resin and three directional (3D) PAN-based carbon fiber with CVI carbon matrix C/C composite were investigated for non-heat treated (NHT) and heat treated (HT) materials through the thickness (z-direction). Heat treatment was performed at 1800, 2100 and 2400 oC for 1-hr in inert argon atmosphere. Thermal diffusivity, heat capacity and bulk density were measured to calculate thermal conductivity. Thermal diffusivity and conductivity was the highest for 3D C/C heat treated at maximum temperature with non-heat treated one exhibiting the lowest one. Similarly, 2D C/C heat treated at maximum temperature exhibited the highest thermal diffusivity and thermal conductivity. Polarized light microscopy (PLM) images of HTT C/C show a progressive improvement in microstructure when compared to NHT C/C. However, HTT 2D and 3D C/C composites exhibited extensive shrinkage of charred resin and CVI carbon matrix, respectively, from fibers resulting in intra and inter-bundles cracking when compared to NHT one. Raman spectroscopy and XRD results of NHT and HTT C/C indicated increased ordering of structure. A progressive improvement in thermal properties was observed with increased heat treatment temperatures.

Iqbal, Sardar S. [Southern Illinois University; Dinwiddie, Ralph Barton [ORNL; Porter, Wallace D [ORNL; Lance, Michael J [ORNL; Fillip, Peter [Southern Illinois University

2011-01-01T23:59:59.000Z

235

Role of thermal conduction in an advective accretion with bipolar outflows  

E-Print Network (OSTI)

Steady-state advective accretion flows in the presence of thermal conduction are studied. All three components of velocity in a spherical coordinates are considered and the flow displays both inflowing and outflowing regions according to our similarity solutions. Thermal conductivity provides latitudinal energy transport and so, the flow rotates more slowly and becomes hotter with increasing thermal conductivity coefficient. We also show that opening angle of the outflow region decreases as thermal conduction becomes stronger.

Khajenabi, Fazeleh

2013-01-01T23:59:59.000Z

236

SENSIBLE HEAT STORAGE FOR A SOLAR THERMAL POWER PLANT  

E-Print Network (OSTI)

nZ The brick and gas heat capacities, cross-sectional areaConductivity! 10B9"K, W! mOK Heat Capacity! 1089°K, J/kg"KHelium has the highest heat capacity per unit mass and the

Baldwin, Thomas F.

2011-01-01T23:59:59.000Z

237

Experimental Investigation on Thermal Properties of a Steel-jacketed Steam Heating Pipeline with Vacuum Insulation  

E-Print Network (OSTI)

The steel-jacketed steam heating pipeline employs vacuum insulation to improve the insulating effect and reduce the corrosion, and hence increases the heat transfer efficiency of the heating network and building energy efficiency. It is important in improving the thermal insulation to investigate the impact of factors that insulate the effects and thermal properties of the pipeline. The thermal insulation of this pipeline comprises the vacuum layer and the insulating material layer. Experiments were performed to measure the combined heat transfer and equivalent thermal conductivities of the insulating material in the vacuum and rarefied air employed in the pipeline's insulation. The thermal properties of this type of insulation at vacuum pressures of 0.5~1013mbar, employing thermal media temperatures of 343~573K and with different thicknesses of vacuum layer, are discussed for this pipeline, for which diameters of inner steel pipe/steel jacket are DN50/DN250, DN100/DN300, DN200/DN500 and DN500/DN850, respectively. The results show that reduction in vacuum pressure reduces the heat loss in the pipeline. The equivalent thermal conductivity of the insulating material layer is distinctively lower than the vacuum layer, but decreasing the vacuum pressure improves the insulating effect of vacuum layer substantially more than insulating the material layer. As the vacuum pressure decreases from 1013mbar (atmospheric pressure) to 10mbar at the thermal media temperature of 523K e.g., the reduction of equivalent thermal conductivities of vacuum layer is approximately three times greater than that of insulating material layer. The equivalent thermal conductivities of the vacuum layer are lower and decease faster as the vacuum pressure is lower than 100mbar, but the equivalent thermal conductivities of insulating material layer are lower and decease faster as the vacuum pressure is lower than 50mbar. The pressure in vacuum insulation should be controlled lower than 20mbar to achieve desirable insulating effects. Every 10mm addition of thickness of insulating material layer (every 10mm reduction of thickness of vacuum layer) decreases the heat loss of approximately 6.8 percent at the vacuum pressure of 0.5mbar.

Na, W.; Zou, P.

2006-01-01T23:59:59.000Z

238

Anomalous Heat Conduction in One-Dimensional Momentum-Conserving Systems Onuttom Narayan1,2  

E-Print Network (OSTI)

Anomalous Heat Conduction in One-Dimensional Momentum-Conserving Systems Onuttom Narayan1 will obey Fourier's law of conduction j ÿrT; (1) where T is the local temperature and is the heat con but not divergent conduc- tivity [3].) Recently, it has been argued [9] that such anomalous heat conduction occurs

California at Santa Cruz, University of

239

Equilibration and Universal Heat Conduction in Fermi-Pasta-Ulam Chains Trieu Mai,1  

E-Print Network (OSTI)

Equilibration and Universal Heat Conduction in Fermi-Pasta-Ulam Chains Trieu Mai,1 Abhishek Dhar,2 heat conduction. The reason why earlier simulations have obtained systematically higher exponents not been fully inves- tigated, even though the discussion of heat conductivity is in terms of Fourier's law

California at Santa Cruz, University of

240

United States Department of Energy Thermally Activated Heat Pump Program  

Science Conference Proceedings (OSTI)

The US Department of Energy (DOE) is working with partners from the gas heating and cooling industry to improve energy efficiency using advance absorption technologies, to eliminate chlorofluorocarbons (CFCs) and hydrochlorofluorocarbons (HCFCs), to reduce global warming through more efficient combustion of natural gas, and to impact electric peak demand of air conditioning. To assist industry in developing these gas heating and cooling absorption technologies, the US DOE sponsors the Thermally Activated Heat Pump Program. It is divided into five key activities, addressing residential gas absorption heat pumps, large commercial chillers, advanced absorption fluids, computer-aided design, and advanced ``Hi-Cool`` heat pumps.

Fiskum, R.J. [USDOE, Washington, DC (United States); Adcock, P.W.; DeVault, R.C. [Oak Ridge National Lab., TN (United States)

1996-06-01T23:59:59.000Z

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.


241

Thermal Performance of the Multilayered Honeycomb Microchannel Heat Sink  

Science Conference Proceedings (OSTI)

To develop a high effectiveness, reliable, cost-effective compact heat exchanger is one of the key issues for effective use of thermal energy. By stacking multilayered flat thin rectangular plates with a number of regular honeycomb cells etched inside, ... Keywords: multilayer, honeycomb, microchannel, heat sink

Yonglu Liu; Xiaobing Luo; Wei Liu; Zhifeng Huang

2009-10-01T23:59:59.000Z

242

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

243

Universal properties of thermal and electrical conductivity of gauge theory plasmas from holography  

E-Print Network (OSTI)

We show that for CFT's admitting gravity duals, thermal conductivity is fixed by central charges in a universal manner. We also discuss possible bound on thermal conductivity. Using this universality relation exhibited by thermal conductivity, we show how to express electrical conductivity in terms of thermodynamical quantities even in the presence of chemical potential i.e. electrical conductivity can be calculated without writing down perturbation equations and solving them even at nonvanishing chemical potential.

Jain, Sachin

2009-01-01T23:59:59.000Z

244

Modeling Simulation Of Pyrolysis Of Biomass: Effect Of Thermal Conductivity, Reactor Temperature And Particle Size On Product Concentrations  

E-Print Network (OSTI)

The simultaneous chemical kinetics and heat transfer model is used to predict the effects of the most important physical and thermal properties (thermal conductivity, reactor temperature and particle size) of the feedstock on the convective-radiant pyrolysis of biomass fuels. The effects of these parameters have been analyzed for different geometries such as slab, cylinder and sphere. Finite difference method is employed for solving heat transfer model equation while Runge-Kutta 4 th order method is used for solving chemical kinetics model equations. Simulations are carried out for equivalent radius ranging from 0.0000125 m to 0.02 m, and temperature ranging from 303 K to 2100 K.

Chaurasia And Babu; A. S. Chaurasia; B. V. Babu

2003-01-01T23:59:59.000Z

245

Length dependence of heat conduction in one-dimensional lattices with asymmetric inter-particle interactions  

E-Print Network (OSTI)

We have numerically studied heat conduction in a few one-dimensional momentum conserving lattices with asymmetric inter-particle interactions by the non-equilibrium heat bath method, the equilibrium Green-Kubo method, and the heat current power spectra analysis. Very strong finite-size effects are clearly observed. Such effects make the heat conduction obey a Fourier-like law in a wide regime of lattice lengths. However, in yet longer lattice lengths, the heat conductivity regains its power-law divergence. Therefore the power-law divergence of the heat conductivity in the thermodynamic limit is verified, as is expected by many existing theories.

Wang, Lei; Li, Baowen

2013-01-01T23:59:59.000Z

246

Spatially localized measurement of thermal conductivity using a hybrid photothermal technique  

SciTech Connect

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

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

2012-05-01T23:59:59.000Z

247

Aquifer thermal energy (heat and chill) storage  

DOE Green Energy (OSTI)

As part of the 1992 Intersociety Conversion Engineering Conference, held in San Diego, California, August 3--7, 1992, the Seasonal Thermal Energy Storage Program coordinated five sessions dealing specifically with aquifer thermal energy storage technologies (ATES). Researchers from Sweden, The Netherlands, Germany, Switzerland, Denmark, Canada, and the United States presented papers on a variety of ATES related topics. With special permission from the Society of Automotive Engineers, host society for the 1992 IECEC, these papers are being republished here as a standalone summary of ATES technology status. Individual papers are indexed separately.

Jenne, E.A. (ed.)

1992-11-01T23:59:59.000Z

248

DIRECT MEASUREMENT OF HEAT FLUX FROM COOLING LAKE THERMAL IMAGERY  

SciTech Connect

Laboratory experiments show a linear relationship between the total heat flux from a water surface to air and the standard deviation of the surface temperature field, {sigma}, derived from thermal images of the water surface over a range of heat fluxes from 400 to 1800 Wm{sup -2}. Thermal imagery and surface data were collected at two power plant cooling lakes to determine if the laboratory relationship between heat flux and {sigma} exists in large heated bodies of water. The heat fluxes computed from the cooling lake data range from 200 to 1400 Wm{sup -2}. The linear relationship between {sigma} and Q is evident in the cooling lake data, but it is necessary to apply band pass filtering to the thermal imagery to remove camera artifacts and non-convective thermal gradients. The correlation between {sigma} and Q is improved if a correction to the measured {sigma} is made that accounts for wind speed effects on the thermal convection. Based on more than a thousand cooling lake images, the correlation coefficients between {sigma} and Q ranged from about 0.8 to 0.9.

Garrett, A; Eliel Villa-Aleman, E; Robert Kurzeja, R; Malcolm Pendergast, M; Timothy Brown, T; Saleem Salaymeh, S

2007-12-19T23:59:59.000Z

249

Invited paper for the 30th International Thermal Conductivity ...  

Science Conference Proceedings (OSTI)

... of the FRM influences the radiative heat transfer between a ... dry cycling, humidity, impact resistance, industrial atmosphere, salt spray, temperature ...

2010-10-28T23:59:59.000Z

250

Evaporation and condensation of spherical interstellar clouds. Self-consistent models with saturated heat conduction and cooling  

E-Print Network (OSTI)

Shortened version: The fate of IS clouds embedded in a hot tenuous medium depends on whether the clouds suffer from evaporation or whether material condensates onto them. Analytical solutions for the rate of evaporative mass loss from an isolated spherical cloud embedded in a hot tenuous gas are deduced by Cowie & McKee (1977). In order to test the validity of the analytical results for more realistic IS conditions the full hydrodynamical equations must be treated. Therefore, 2D numerical simulations of the evolution of IS clouds %are performed with different internal density structures and surrounded by a hot plasma reservoir. Self-gravity, interstellar heating and cooling effects and heat conduction by electrons are added. Classical thermal conductivity of a fully ionized hydrogen plasma and saturated heat flux are considered. Using pure hydrodynamics and classical heat flux we can reproduce the analytical results. Heat flux saturation reduces the evaporation rate by one order of magnitude below the analytical value. The evolution changes totally for more realistic conditions when interstellar heating and cooling effects stabilize the self-gravity. Evaporation then turns into condensation, because the additional energy by heat conduction can be transported away from the interface and radiated off efficiently from the cloud's inner parts. I.e. that the saturated heat flux consideration is inevitable for IS clouds embedded in hot tenuous gas. Various consequences are discussed in the paper.

W. Vieser; G. Hensler

2007-09-05T23:59:59.000Z

251

Improved Thermal Properties of In Situ Formed Al/AlN Composites ...  

Science Conference Proceedings (OSTI)

Abstract Scope, Thermal conduction and thermal expansion behaviors of heat sink materials are critical for microelectronic packaging because high thermal ...

252

An evaluation of the thermal characteristics of a flat plate heat pipe spreader  

E-Print Network (OSTI)

An evaluation of the thermal characteristics of a flat plate heat pipe spreader was performed through an analytical, numerical, and experimental analysis. The physical system considered was comprised of a high heat flux heat source attached to the center of a flat plate heat pipe, mounted at the base of a plate-finned heat sink and cooled by forced convection. In the analysis, the theoretical maximum operating conditions for the heat pipe are predicted, and it is found that the specific heat pipe configuration would most likely fail based on capillary limitations of the wick structure for conditions typical of electronic cooling applications. The mass and heat transfer processes which contribute to the capillary limitation were considered in theory, and a novel technique which utilizes well-known conventional heat pipe relations for pressure loss was developed to estimate the point of heat pipe failure. In addition, a thermal resistance network was developed in an effort to predict the temperature drop across the heat pipe spreader. Through a separate approach, a numerical model was developed to solve the conjugate problem of heat transfer in the heat pipe/heat sink with turbulent forced convection. In this approach, the heat pipe was modeled as a solid material having a high effective conductivity. Finally, the system was tested experimentally, and the results were compared to the analytical and numerical results. It was found that the capillary limit model over-predicted the measured point of heat pipe failure by several orders of magnitude, and the resistance model under-represented the actual resistance by a factor of 2 to 3. In addition, a change in thermal resistance with power input was discovered during experimentation that was not predicted by the analysis. The numerical model was compared to the experimental results and a relation for the effective conductivity as a function of power input was determined. Complexities associated with the internal heat and mass transfer processes of the flat plate heat pipe spreader were thoroughly discussed and the discrepancies between the experimental and analytical results were examined.

Chesser, Jason Blake

2000-01-01T23:59:59.000Z

253

Normal heat conduction in 1-dimensional momentum-conserved lattices of asymmetric interactions  

E-Print Network (OSTI)

We numerically investigate the heat conduction behavior of one-dimensional momentum-conserved lattice systems with {\\it asymmetric} interactions. The heat conductivity is measured by coupling the system to two heat baths at different temperatures. It is found that with certain degree of interaction asymmetry, the heat conductivity becomes size-independent in the thermodynamical limit. This result is in clear contrast to the well accepted viewpoint that Fourier's law is generally violated in low dimensional momentum-conserved systems, suggesting the heat conduction behavior of observed in {\\it nonequilibrium} stationary states may differ essentially from the prediction of linear response theory.

Zhong, Yi; Wang, Jiao; Zhao, Hong

2011-01-01T23:59:59.000Z

254

Thermal conductance and rectification of asymmetric tilt grain boundary in graphene  

E-Print Network (OSTI)

We have investigated the lattice thermal transport across the asymmetry tilt grain boundary between armchair and zigzag grains by using nonequilibrium molecular dynamics (NEMD). We have observed significant temperature drop and ultralow temperature-dependent thermal boundary resistance. Importantly, we find an unexpected thermal rectification phenomenon, i.e, the thermal conductivity and Kapitza conductance is asymmetric with respect to the thermal transport direction. And the effect of thermal rectification could be amplified by increasing the difference of temperature imposed on two sides. Our results propose a new promising kind of thermal rectifier and phonon diodes from polycrystalline graphene without delicate manupulation of the atomic structures.

Cao, Hai-Yuan; Gong, Xin-Gao

2011-01-01T23:59:59.000Z

255

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

Science Conference Proceedings (OSTI)

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

256

Evaluating the ignition sensitivity of thermal battery heat pellets  

DOE Green Energy (OSTI)

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

257

Thermal performance of a geofluid direct-contact heat exchanger  

DOE Green Energy (OSTI)

A sieve-tray direct-contact heat exchanger was used to transfer heat from a 280/sup 0/F geothermal fluid to the working fluid, isobutane, in the Raft River 60kW prototype plant. A series of experiments were run at different working fluid-to-geofluid flow ratios which produced different boiling conditions. In this paper, the results of these experiments are analyzed on the basis of thermal performance. The flow ratio, the geofluid outlet temperature, the working fluid inlet temperature, the amount of working fluid dissolved or entrained in geofluid, and tray efficiency are varied and preheating temperature profiles are calculated. These are compared with the experimentally obtained temperature profiles and the relative effects of the variables are evaluated. From this, it was determined that the approach temperature difference was on the order of .1/sup 0/ after 17 preheating trays, and the tray efficiencies, which appear to be about the same for all trays, reached approx. 70%. It was also determined that entrainment has a negligible effect on column thermal performance. The thermal performance of this column compares favorably with a spray-tower direct-contact heat exchanger and a shell-and-tube heat exchanger in terms of overall heat-transfer coefficient. Distributor tray and boiling tray behavior are discussed. These is some discussion of operations and thermal hydraulics as well.

Wiggins, D.J.; Mines, G.L.; Wahl, E.

1983-01-01T23:59:59.000Z

258

Investigation on the Thermal Conductivity of Resin Composite ...  

Science Conference Proceedings (OSTI)

A gas pycnometer was used for measuring volume. The specific heat of the ... Differential Characterization of Ikperejere Iron shale and Iron Sandstone Deposit.

259

Reversible temperature regulation of electrical and thermal conductivity using liquid–solid phase transitions  

E-Print Network (OSTI)

Reversible temperature tuning of electrical and thermal conductivities of materials is of interest for many applications, including seasonal regulation of building temperature, thermal storage and sensors. Here we introduce ...

Zheng, Ruiting

260

Thermal conductivity from first-principles in bulk, disordered, and nanostructured materials  

E-Print Network (OSTI)

Thermal conductivity is an important transport property that plays a vital role in applications such as high efficiency thermoelectric devices as well as in thermal management of electronics. We present a first-principles ...

Garg, Jivtesh

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.


261

Advanced technology thermal energy storage and heat exchange systems for solar applications: a survey of current research  

DOE Green Energy (OSTI)

A survey is presented of the advanced research and development projects underway in the U.S. in all of the known media and methods for storing and transferring thermal energy in solar applications. The technologies reviewed include innovative heat exchange and heat transport methods, advanced sensible heat storage in water, rocks, earth and combinations of these for both short term and annual storage, phase change materials, and reversible chemical reactions. This survey is presented in a structure of categories and subcategories of thermal energy storage and heat transfer technology. Within a given subcategory the project descriptions are listed under the name of the organizations conducting the work, arranged in alphabetical order.

Michaels, A. I.

1978-01-01T23:59:59.000Z

262

Thermal conduction and particle transport in strong MHD turbulence, with application to galaxy-cluster plasmas  

E-Print Network (OSTI)

We investigate field-line separation in strong MHD turbulence analytically and with 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 5-10 relative to the Spitzer thermal conductivity of a non-magnetized plasma. We also estimate how the thermal conductivity would be affected by efficient turbulent resistivity.

Benjamin D. G. Chandran; Jason L. Maron

2003-03-11T23:59:59.000Z

263

Design and operation of solar thermal heat transfer systems  

Science Conference Proceedings (OSTI)

The importance of heat transfer systems in the collection and use of solar energy is discussed. The success or failure of many solar energy systems has been determined by the design of the heat transfer system. This report includes a short summary of some of the DOE sponsored solar industrial process heat sites. From the design, construction, and operation of these systems many lessons were learned which will be important to designers and potential users of solar thermal systems. Also included is a discussion of solar collector foundation over-design that has increased the collector system costs.

Rush, E.E.

1985-01-01T23:59:59.000Z

264

Effect of TiO2 on the Conduction Heat Transfer of Mold Flux  

Science Conference Proceedings (OSTI)

Symposium, 2nd International Symposium on High-Temperature Metallurgical Processing. Presentation Title, Effect of TiO2 on the Conduction Heat Transfer of

265

On the Critical Behaviour of Heat Conducting Sphere out of Hydrostatic Equilibrium  

E-Print Network (OSTI)

We comment further on the behaviour of a heat conducting fluid when a characteristic parameter of the system approaches a critical value.

L. Herrera; J. Martinez

1997-04-09T23:59:59.000Z

266

High Rayleigh number thermal convection in volumetrically heated spherical shells  

E-Print Network (OSTI)

parameterizations for the average temperature of the shell and for the temperature jump across the thermal boundary properties, cores and overlying shells (e.g., silicate mantles or ice layers) of rocky planets and icy moons, including the rheology of the material, the presence of phase transitions, and the mode of heating

Tackley, Paul J.

267

Three-dimensional effect on the effective thermal conductivity of porous media  

E-Print Network (OSTI)

conductivity of multiphase random porous media. The energymorphology of multiphase random porous media. Wang’sfor multiphase conjugate heat transfer through a porous

Wang, Moran R Dr.; Wang, J K; Pan, N; Chen, S Y; He, J H

2007-01-01T23:59:59.000Z

268

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 on the market. Three primary variables, including number of wire mesh layers, filler material, and temperature dependence were studied using an apparatus that was part of L.I.C.H.E.N (LabVIEW Integrated Conduction Heat Experiment Network), a setup whose basic components allow three vertically stacked samples to be thermally and mechanically controlled. Knowing the temperature profile in the upper and lower samples allows for determination of thermal conductivity of the middle material through the use of Fourier?s law. The numbers of layers investigated were two, four, six, and eight, with each separated by a metallic liner. The filler materials included air, s15, s35 and s60HS 3MTM hollow glass microspheres. The experiments were conducted at four temperatures of 300, 330, 366, and 400K with an interface pressure of 20 Psi. The experimental results indicated the ?number of layers? used was the primary factor in determining the effective thermal conductivity value. The addition of hollow glass microspheres as filler material resulted in statistically insignificant changes in effective thermal conductivity. Increasing the number of wire mesh layers resulted in a corresponding increase in effective thermal conductivity of the insulation. Changes in temperature had little to no effect on thermal conductivity. The effective thermal conductivity values for the proposed insulation structure ranged from 0.22 to 0.65 W/m-K, the lowest of which came from the two layer case having air as filler material. The uncertainties associated with the experimental results fell between 10 to 20 percent in all but a few cases. In the best performing cases, when compared with existing insulation technologies, thermal conductivity was approximately 3 to 10 times higher than these methods of insulation. Thus, the proposed insulation scheme with hollow glass-sphere filler material does not represent superior technology, and would be deemed uncompetitive with those readily available in the insulation market.

Mckenna, Sean

2008-12-01T23:59:59.000Z

269

Non-Fourier heat conduction in a single-walled carbon nanotube: Classical molecular dynamics simulations  

SciTech Connect

Nonstationary heat conduction in a single-walled carbon nanotube was investigated by applying a local heat pulse with duration of subpicoseconds. The investigation was based on classical molecular dynamics simulations, where the heat pulse was generated as coherent fluctuations by connecting a thermostat to the local cell for a short duration. The heat conduction through the nanotube was observed in terms of spatiotemporal temperature profiles. Results of the simulations exhibit non-Fourier heat conduction where a distinct amount of heat is transported in a wavelike form. The geometry of carbon nanotubes allows us to observe such a phenomenon in the actual scale of the material. The resulting spatiotemporal profile was compared with the available macroscopic equations, the so-called non-Fourier heat conduction equations, in order to investigate the applicability of the phenomenological models to a quasi-one-dimensional system. The conventional hyperbolic diffusion equation fails to predict the heat conduction due to the lack of local diffusion. It is shown that this can be remedied by adopting a model with dual relaxation time. Further modal analyses using wavelet transformations reveal a significant contribution of the optical phonon modes to the observed wavelike heat conduction. The result suggests that, in carbon nanotubes with finite length where the long-wavelength acoustic phonons behave ballistically, even optical phonons can play a major role in the non-Fourier heat conduction.

Shiomi, Junichiro; Maruyama, Shigeo [Department of Mechanical Engineering, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656 (Japan)

2006-05-15T23:59:59.000Z

270

Experimental measurements of the thermal conductivity of ash deposits: Part 1. Measurement technique  

Science Conference Proceedings (OSTI)

This paper describes a technique developed to make in situ, time-resolved measurements of the effective thermal conductivity of ash deposits formed under conditions that closely replicate those found in the convective pass of a commercial boiler. Since ash deposit thermal conductivity is thought to be strongly dependent on deposit microstructure, the technique is designed to minimize the disturbance of the natural deposit microstructure. Traditional techniques for measuring deposit thermal conductivity generally do not preserve the sample microstructure. Experiments are described that demonstrate the technique, quantify experimental uncertainty, and determine the thermal conductivity of highly porous, unsintered deposits. The average measured conductivity of loose, unsintered deposits is 0.14 {+-} 0.03 W/(m K), approximately midway between rational theoretical limits for deposit thermal conductivity.

A. L. Robinson; S. G. Buckley; N. Yang; L. L. Baxter

2000-04-01T23:59:59.000Z

271

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

272

THE THERMAL PROPERTIES OF GASES FOR USE IN REACTOR HEAT-TRANSFER CALCULATIONS  

DOE Green Energy (OSTI)

A revised standard set of values of the thermal conductivities, viscosities, and specific heats of hydrogen, helium, nitrogen, argon, krypton, xenon, carbon dioxide, and air over the temperature range 0 to 1000 deg C is presented for ease in heat-transfer calculations and experiments. Selected experimental values and an indication of the methods of calculation of the thermal conductivity and viscosity of some binary and ternary gas mixtures are also included. Attention was also given to the variation of these gaseous properties at pressures above atmospheric. A selection of published work, mainly since 1954, collected from a literature survey is reviewed and the values quoted are displayed in tabular and/or graphical form, from which standard graphs were derived. (auth)

Massey, G.V.

1960-07-01T23:59:59.000Z

273

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)

of heat fluxes from CFD and conduction simulations for theapproach to solve the conduction heat-transfer equation. TheFluid Dynamics and Conduction Simulations of Heat Transfer

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

2003-01-01T23:59:59.000Z

274

A modified Tikhonov regularization method for a spherically symmetric three-dimensional inverse heat conduction problem  

Science Conference Proceedings (OSTI)

This paper deals with a spherically symmetric three-dimensional inverse heat conduction problem of determining the internal surface temperature distribution of a hollow sphere from the measured data at a fixed location inside it. This is an ill-posed ... Keywords: Error estimate, Ill-posed problem, Regularization, Spherically symmetric inverse heat conduction problem

Wei Cheng; Chu-Li Fu; Zhi Qian

2007-07-01T23:59:59.000Z

275

Cylindrical model of transient heat conduction in automotive fuse using conservative averaging method  

Science Conference Proceedings (OSTI)

Cylindrical mathematical model of automotive fuse is considered in this paper. Initially, partial differential equations of the transient heat conduction are given to describe heat-up process in the fuse. Conservative averaging method is used to obtain ... Keywords: analytical approximation, automotive fuse, conservative averaging, heat transfer, quasi-linear, transient process

Raimonds Vilums; Hans-Dieter Liess; Andris Buikis; Andis Rudevics

2008-12-01T23:59:59.000Z

276

COYOTE : a finite element computer program for nonlinear heat conduction problems. Part I, theoretical background.  

SciTech Connect

The need for the engineering analysis of systems in which the transport of thermal energy occurs primarily through a conduction process is a common situation. For all but the simplest geometries and boundary conditions, analytic solutions to heat conduction problems are unavailable, thus forcing the analyst to call upon some type of approximate numerical procedure. A wide variety of numerical packages currently exist for such applications, ranging in sophistication from the large, general purpose, commercial codes, such as COMSOL, COSMOSWorks, ABAQUS and TSS to codes written by individuals for specific problem applications. The original purpose for developing the finite element code described here, COYOTE, was to bridge the gap between the complex commercial codes and the more simplistic, individual application programs. COYOTE was designed to treat most of the standard conduction problems of interest with a user-oriented input structure and format that was easily learned and remembered. Because of its architecture, the code has also proved useful for research in numerical algorithms and development of thermal analysis capabilities. This general philosophy has been retained in the current version of the program, COYOTE, Version 5.0, though the capabilities of the code have been significantly expanded. A major change in the code is its availability on parallel computer architectures and the increase in problem complexity and size that this implies. The present document describes the theoretical and numerical background for the COYOTE program. This volume is intended as a background document for the user's manual. Potential users of COYOTE are encouraged to become familiar with the present report and the simple example analyses reported in before using the program. The theoretical and numerical background for the finite element computer program, COYOTE, is presented in detail. COYOTE is designed for the multi-dimensional analysis of nonlinear heat conduction problems. A general description of the boundary value problems treated by the program is presented. The finite element formulation and the associated numerical methods used in COYOTE are also outlined. Instructions for use of the code are documented in SAND2010-0714.

Glass, Micheal W.; Hogan, Roy E., Jr.; Gartling, David K.

2010-03-01T23:59:59.000Z

277

Investigation of Heat Conductivity in Relativistic Systems using a Partonic Cascade  

E-Print Network (OSTI)

Motivated by the classical picture of heat flow we construct a stationary temperature gradient in a relativistic microscopic transport model. Employing the relativistic Navier-Stokes ansatz we extract the heat conductivity {\\kappa} for a massless Boltzmann gas using only binary collisions with isotropic cross sections. We compare the numerical results to analytical expressions from different theories and discuss the final results. The directly extracted value for the heat conductivity can be referred to as a literature reference within the numerical uncertainties.

M. Greif; F. Reining; I. Bouras; G. S. Denicol; Z. Xu; C. Greiner

2013-01-07T23:59:59.000Z

278

Investigation of Heat Conductivity in Relativistic Systems using a Partonic Cascade  

E-Print Network (OSTI)

Motivated by the classical picture of heat flow we construct a stationary temperature gradient in a relativistic microscopic transport model. Employing the relativistic Navier-Stokes ansatz we extract the heat conductivity {\\kappa} for a massless Boltzmann gas using only binary collisions with isotropic cross sections. We compare the numerical results to analytical expressions from different theories and discuss the final results. The directly extracted value for the heat conductivity can be referred to as a literature reference within the numerical uncertainties.

Greif, M; Bouras, I; Denicol, G S; Xu, Z; Greiner, C

2013-01-01T23:59:59.000Z

279

The role of asymmetric inter-particle interactions in heat conduction  

E-Print Network (OSTI)

We numerically calculate the heat conductivity by using the Green-Kubo formula to confirm that asymmetric inter-particle interactions in one-dimensional momentum conserving lattices can induce normal heat conduction. The Lennard-Jones (L-J) inter-particle interactions are focused in view of their practical significance. The effects of the asymmetric inter-particle interactions on the cross-correlation coefficient between the heat and mass fluxes are also discussed.

Chen, Shunda; Wang, Jiao; Zhao, Hong

2012-01-01T23:59:59.000Z

280

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

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

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

282

Heat transfer simulation and thermal measurements of microfabricated x-ray transparent heater stages  

SciTech Connect

A microfabricated amorphous silicon nitride membrane-based nanocalorimeter is proposed to be suitable for an x-ray transparent sample platform with low power heating and built-in temperature sensing. In this work, thermal characterization in both air and vacuum are analyzed experimentally and via simulation. Infrared microscopy and thermoreflectance microscopy are used for thermal imaging of the sample area in air. While a reasonably large isothermal area is found on the sample area, the temperature homogeneity of the entire sample area is low, limiting use of the device as a heater stage in air or other gases. A simulation model that includes conduction, as well as radiation and convection heat loss, is presented with radiation and convection parameters determined experimentally. Simulated temperature distributions show that the homogeneity can be improved by using a thicker thermal conduction layer or reducing the pressure of the gas in the environment but neither are good solutions for the proposed use. A new simple design that has improved temperature homogeneity and a larger isothermal area while maintaining a thin thermal conduction layer is proposed and fabricated. This new design enables applications in transmission x-ray microscopes and spectroscopy setups at atmospheric pressure.

Baldasseroni, C. [Department of Materials Science and Engineering, University of California Berkeley, Berkeley, California 94720 (United States); Queen, D. R.; Cooke, David W.; Hellman, F. [Department of Physics, University of California Berkeley, Berkeley, California 94720 (United States); Maize, K.; Shakouri, A. [Department of Electrical Engineering, University of California Santa Cruz, Santa Cruz, California 95064 (United States)

2011-09-15T23:59:59.000Z

283

SunShot Initiative: Advanced Heat Transfer Fluids and Novel Thermal...  

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

Advanced Heat Transfer Fluids and Novel Thermal Storage Concepts for CSP Generation to someone by E-mail Share SunShot Initiative: Advanced Heat Transfer Fluids and Novel Thermal...

284

Thermal Performance of a Novel Heat Transfer Fluid Containing Multiwalled Carbon Nanotubes and Microencapsulated Phase Change Materials  

E-Print Network (OSTI)

The present research work aims to develop a new heat transfer fluid by combining multiwalled carbon nanotubes (MWCNT) and microencapsulated phase change materials (MPCMs). Stable nanofluids have been prepared using different sizes of multiwalled carbon nanotubes and their properties like thermal conductivity and viscosity have been measured. Microencapsulated phase change material slurries containing microcapsules of octadecane have been purchased from Thies Technology Inc. Tests have been conducted to determine the durability and viscosity of the MPCM slurries. Heat transfer experiments have been conducted to determine the heat transfer coefficients and pressure drop of the MWCNT nanofluids and MPCM slurries under turbulent flow and constant heat flux conditions. The MPCM slurry and the MWCNT nanofluid have been combined to form a new heat transfer fluid. Heat transfer tests have been conducted to determine the heat transfer coefficient and the pressure drop of the new fluid under turbulent flow and constant heat flux conditions. The potential use of this fluid in convective heat transfer applications has also been discussed. The heat transfer results of the MPCM slurry containing octadecane microcapsules was in good agreement with the published literature. The thermal conductivity enhancement obtained for MWCNTs with diameter (60-100 nm) and length (0.5-40?m) was 8.11%. The maximum percentage enhancement (compared to water) obtained in the heat transfer coefficient of the MWCNT nanofluid was in the range of 20-25%. The blend of MPCMs and MWCNTs was highly viscous and displayed a shear thinning behavior. Due to its high viscosity, the flow became laminar and the heat transfer performance was lowered. It was interesting to observe that the value of the maximum local heat transfer coefficient achieved in the case of the blend (laminar flow), was comparable to that obtained in the case of the MPCM slurry (turbulent flow). The pressure drop of the blend was lower than that of the MWCNT nanofluid.

Tumuluri, Kalpana

2010-05-01T23:59:59.000Z

285

Formation of thermal eddies during rf heating of plasma  

SciTech Connect

Moderate power (approx.1 kW) excitation of lower hybrid waves in a linear plasma column is found to increase the reflectivity of the phased waveguide exciter and to change the vertical position of the resonance cone. Probing of the plasma near the mouth of the waveguide reveals that the increased reflection results from an undulation in the plasma surface. We present evidence that this surface distortion is driven by thermal eddies associated with asymmetrical electron heating.

Motley, R.W.; Hooke, W.M.; Anania, G.

1979-07-01T23:59:59.000Z

286

IMPACT OF TEMPERATURE-DEPENDENT RESISTIVITY AND THERMAL CONDUCTION ON PLASMOID INSTABILITIES IN CURRENT SHEETS IN THE SOLAR CORONA  

SciTech Connect

In this paper, we investigate, by means of two-dimensional magnetohydrodynamic simulations, the impact of temperature-dependent resistivity and thermal conduction on the development of plasmoid instabilities in reconnecting current sheets in the solar corona. We find that the plasma temperature in the current-sheet region increases with time and it becomes greater than that in the inflow region. As secondary magnetic islands appear, the highest temperature is not always found at the reconnection X-points, but also inside the secondary islands. One of the effects of anisotropic thermal conduction is to decrease the temperature of the reconnecting X-points and transfer the heat into the O-points, the plasmoids, where it gets trapped. In the cases with temperature-dependent magnetic diffusivity, {eta} {approx} T {sup -3/2}, the decrease in plasma temperature at the X-points leads to (1) an increase in the magnetic diffusivity until the characteristic time for magnetic diffusion becomes comparable to that of thermal conduction, (2) an increase in the reconnection rate, and (3) more efficient conversion of magnetic energy into thermal energy and kinetic energy of bulk motions. These results provide further explanation of the rapid release of magnetic energy into heat and kinetic energy seen during flares and coronal mass ejections. In this work, we demonstrate that the consideration of anisotropic thermal conduction and Spitzer-type, temperature-dependent magnetic diffusivity, as in the real solar corona, are crucially important for explaining the occurrence of fast reconnection during solar eruptions.

Ni Lei; Roussev, Ilia I.; Lin Jun [Yunnan Astronomical Observatory, CAS, P.O. Box 110, Kunming 650011, Yunnan (China); Ziegler, Udo, E-mail: leini@ynao.ac.cn, E-mail: iroussev@ifa.hawaii.edu, E-mail: uziegler@aip.de [Leibniz-Institut fuer Astrophysik Potsdam, D-14482 Potsdam (Germany)

2012-10-10T23:59:59.000Z

287

Quantum effects in thermal conduction: Nonequilibrium quantum discord and entanglement  

E-Print Network (OSTI)

We study the process of heat transfer through an entangled pair of two-level system, demonstrating the role of quantum correlations in this nonequilibrium process. While quantum correlations generally degrade with increasing the temperature bias, introducing spatial asymmetry leads to an intricate behavior: Connecting the qubits unequally to the reservoirs one finds that quantum correlations persist and increase with the temperature bias when the system is more weakly linked to the hot reservoir. In the reversed case, linking the system more strongly to the hot bath, the opposite, more natural behavior is observed, with quantum correlations being strongly suppressed upon increasing the temperature bias.

Wu, Lian-Ao

2011-01-01T23:59:59.000Z

288

Quantum effects in thermal conduction: Nonequilibrium quantum discord and entanglement  

E-Print Network (OSTI)

We study the process of heat transfer through an entangled pair of two-level system, demonstrating the role of quantum correlations in this nonequilibrium process. While quantum correlations generally degrade with increasing the temperature bias, introducing spatial asymmetry leads to an intricate behavior: Connecting the qubits unequally to the reservoirs one finds that quantum correlations persist and increase with the temperature bias when the system is more weakly linked to the hot reservoir. In the reversed case, linking the system more strongly to the hot bath, the opposite, more natural behavior is observed, with quantum correlations being strongly suppressed upon increasing the temperature bias.

Lian-Ao Wu; Dvira Segal

2011-05-06T23:59:59.000Z

289

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 tanks and reducing thermal mass. A companion paper, Energy Efficiency Process Heating: Managing Air Flow of the oven/furnace. Reducing the quantity of energy lost to thermal mass in a process heating system saves

Kissock, Kelly

290

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

291

Controlling the Heat Transfer  

Science Conference Proceedings (OSTI)

Through experimental validation that air conduction is shown to be typically the dominant thermal transport mechanism in the contact region, the heat conduction

292

Innovative Miniaturized Heat Pumps for Buildings: Modular Thermal Hub for Building Heating, Cooling and Water Heating  

SciTech Connect

BEETIT Project: Georgia Tech is using innovative components and system design to develop a new type of absorption heat pump. Georgia Tech’s new heat pumps are energy efficient, use refrigerants that do not emit greenhouse gases, and can run on energy from combustion, waste heat, or solar energy. Georgia Tech is leveraging enhancements to heat and mass transfer technology possible in microscale passages and removing hurdles to the use of heat-activated heat pumps that have existed for more than a century. Use of microscale passages allows for miniaturization of systems that can be packed as monolithic full-system packages or discrete, distributed components enabling integration into a variety of residential and commercial buildings. Compared to conventional heat pumps, Georgia Tech’s design innovations will create an absorption heat pump that is much smaller, has higher energy efficiency, and can also be mass produced at a lower cost and assembly time.

2010-09-01T23:59:59.000Z

293

Plate Fin Heat Exchanger Model with Axial Conduction and Variable Properties  

E-Print Network (OSTI)

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 ...

Hansen, B J; Klebaner, A; 10.1063/1.4706971

2012-01-01T23:59:59.000Z

294

Study on the Mode of Power Plant Circulating Water Waste Heat Regenerative Thermal System  

Science Conference Proceedings (OSTI)

Power Plant Circulating Water (PPCW) waste heat recycling is an important way of increasing a power plant’s primary energy ratio. According to the PPCW waste heat regenerative thermal system, the authors propose two modes of heat pump heat regenerative ... Keywords: heat pump, power plant circulating water (PPCW), waste heat recycling, energy saving

Bi Qingsheng; Ma Yanliang; Yang Zhifu

2009-10-01T23:59:59.000Z

295

Problems in suppressing cooling flows in clusters of galaxies by global heat conduction  

E-Print Network (OSTI)

I use a simple analytical model to show that simple heat conduction models cannot significantly suppress cluster cooling flows. I build a static medium where heat conduction globally balances radiative cooling, and then perturb it. I show that a perturbation extending over a large fraction of the cooling flow region will grow to the non-linear regime within a Hubble time. Such perturbations are reasonable in clusters which frequently experience mergers and/or AGN activity. This result strengthens previous findings which show that a steady solution does not exist for a constant heat conduction coefficient.

Noam Soker

2003-02-19T23:59:59.000Z

296

Thermal analysis of heat storage canisters for a solar dynamic, space power system  

DOE Green Energy (OSTI)

A thermal analysis was performed of a thermal energy storage canister of a type suggested for use in a solar receiver for an orbiting Brayton cycle power system. Energy storage for the eclipse portion of the cycle is provided by the latent heat of a eutectic mixture of LiF and CaF/sub 2/ contained in the canister. The chief motivation for the study is the prediction of vapor void effects on temperature profiles and the identification of possible differences between ground test data and projected behavior in microgravity. The first phase of this study is based on a two-dimensional, cylindrical coordinates model using an interim procedure for describing void behavior in 1/minus/g and microgravity. The thermal anaylsis includes the effects of solidification front behavior, conduction in liquid/solid salt and canister materials, void growth and shrinkage, radiant heat transfer across the void, and convection in the melt due to Marangoni-induced flow and, in 1/minus/g, flow due to density gradients. A number of significant differences between 1/minus/g and 0/minus/g behavior were found. These resulted from differences in void location relative to the maximum heat flux and a significantly smaller effective conductance in 0/minus/g due to the absence of gravity-induced convection.

Wichner, R.P.; Solomon, A.D.; Drake, J.B.; Williams, P.T.

1988-04-01T23:59:59.000Z

297

The Geometric Characterization and Thermal Performance of a Microchannel Heat Exchanger  

E-Print Network (OSTI)

The Geometric Characterization and Thermal Performance of a Microchannel Heat Exchanger for Diesel exchanger that extracts the heat from the exhaust. In this study, a cross-flow microchannel heat exchanger was geometrically examined and thermally tested under laboratory conditions. The heat exchanger, referred

Tullos, Desiree

298

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

299

Theoretical investigation of the impact of grain boundaries and fission gases on UO2 thermal conductivity  

SciTech Connect

Thermal conductivity is one of the most important metrics of nuclear fuel performance. Therefore, it is crucial to understand the impact of microstructure features on thermal conductivity, especially since the microstructure evolves with burn-up or time in the reactor. For example, UO{sub 2} fuels are polycrystalline and for high-burnup fuels the outer parts of the pellet experience grain sub-division leading to a very fine grain structure. This is known to impact important physical properties such as thermal conductivity as fission gas release. In a previous study, we calculated the effect of different types of {Sigma}5 grain boundaries on UO{sub 2} thermal conductivity and predicted the corresponding Kapitza resistances, i.e. the resistance of the grain boundary in relation to the bulk thermal resistance. There have been reports of pseudoanisotropic effects for the thermal conductivity in cubic polycrystalline materials, as obtained from molecular dynamics simulations, which means that the conductivity appears to be a function of the crystallographic direction of the temperature gradient. However, materials with cubic symmetry should have isotropic thermal conductivity. For this reason it is necessary to determine the cause of this apparent anisotropy and in this report we investigate this effect in context of our earlier simulations of UO{sub 2} Kapitza resistances. Another source of thermal resistance comes from fission products and fission gases. Xe is the main fission gas and when generated in sufficient quantity it dissolves from the lattice and forms gas bubbles inside the crystalline structure. We have performed studies of how Xe atoms dissolved in the UO{sub 2} matrix or precipitated as bubbles impact thermal conductivity, both in bulk UO{sub 2} and in the presence of grain boundaries.

Du, Shiyu [Los Alamos National Laboratory; Andersson, Anders D. [Los Alamos National Laboratory; Germann, Timothy C. [Los Alamos National Laboratory; Stanek, Christopher R. [Los Alamos National Laboratory

2012-05-02T23:59:59.000Z

300

Thermal desorption treatability test conducted with VAC*TRAX Unit  

SciTech Connect

In 1992, Congress passed the Federal Facilities Compliance Act, requiring the U.S. Department of Energy (DOE) to treat and dispose of its mixed waste in accordance with Resource Conservation and Recovery Act (RCRA) treatment standards. In response to the need for mixed-waste treatment capacity, where off-site commercial treatment facilities do not exist or cannot be used, the DOE Albuquerque Operations Office (DOE-AL) organized a Treatment Selection Team to match mixed waste with treatment options and develop a strategy for treatment of mixed waste. DOE-AL manages nine sites with mixed-waste inventories. The Treatment Selection Team determined a need to develop mobile treatment units (MTUs) to treat waste at the sites where the wastes are generated. Treatment processes used for mixed wastes must remove the hazardous component (i.e., meet RCRA treatment standards) and contain the radioactive component in a form that will protect the worker, public, and environment. On the basis of the recommendations of the Treatment Selection Team, DOE-AL assigned projects to the sites to bring mixed-waste treatment capacity on-line. The three technologies assigned to the DOE Grand Junction Projects Office (DOE-GJPO) include thermal desorption (TD), evaporative oxidation, and waste water evaporation.

1996-01-01T23:59:59.000Z

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

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

302

Development of plastic heat exchangers for ocean thermal energy conversion. Final report, August 1976--December 1978  

DOE Green Energy (OSTI)

Materials and processes have been selected and design information obtained for plastic ocean thermal energy conversion (OTEC) heat exchangers as the result of a program comprising five types of laboratory experiments. Tests to evaluate the chemical resistance of seven commercially available thermoplastics to sea water and several possible working fluids were conducted with emphasis placed on compatibility with ammonia. Environmental rupture tests involving exposure of stressed specimens to sea water or liquid ammonia indicated that the high density polyethylene (HDPE) is the best suited candidate and produced an extrapolated 100,000 hour failure stress of 1060 psi for HDPE. Long term durability tests of extruded HDPE plate-tube panel confirmed that plastic heat transfer surface is mechanically reliable in an OTEC environment. Thermal conductivity measurements of acetylene black filled HDPE indicated that conductivity may be increased by 50% with a 35% by weight filler loading. The permeability coefficient measured for liquid ammonia through HDPE was higher than previous estimates. Test showed that the rate can be significantly reduced by sulfonation of HDPE. A review of biofouling mechanisms revealed that the permeable nature of the plastic heat exchanger surface may be used to control primary biofouling form formation by allowing incorporation of non-toxic organic repellents into the plastic. A preliminary design and fabrication development program suggests that construction of an ammonia condenser test unit is feasible using currently available materials and manufacturing techniques.

Hart, G.K.; Lee, C.O.; Latour, S.R.

1979-01-01T23:59:59.000Z

303

Molecular dynamics analysis of spectral characteristics of phonon heat conduction in silicon  

E-Print Network (OSTI)

Due to the technological significance of silicon, its heat conduction mechanisms have been studied extensively. However, there have been some lingering questions surrounding the phonon mean free path and importance of ...

Henry, Asegun Sekou Famake

2006-01-01T23:59:59.000Z

304

A Blow-up Criterion for Two Dimensional Compressible Viscous Heat-Conductive Flows  

E-Print Network (OSTI)

We establish a blow-up criterion in terms of the upper bound of the density and temperature for the strong solution to 2D compressible viscous heat-conductive flows. The initial vacuum is allowed.

Fang, Daoyuan; Zhang, Ting

2011-01-01T23:59:59.000Z

305

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

306

Cluster expansion and optimization of thermal conductivity in SiGe nanowires  

E-Print Network (OSTI)

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

Chan, Maria K.

307

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

Science Conference Proceedings (OSTI)

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

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

2012-01-01T23:59:59.000Z

308

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

309

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

310

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

E-Print Network (OSTI)

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

Marconnet, Amy M.

311

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

312

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

E-Print Network (OSTI)

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

Lundstrom, L.

2011-01-01T23:59:59.000Z

313

Thermal Conductivity of Wood-Derived Graphite and Copper-Graphite  

SciTech Connect

The thermal conductivity of wood-derived graphite and graphite/copper composites was studied both experimentally and using finite element analysis. The unique, naturally-derived, anisotropic porosity inherent to wood-derived carbon makes standard porosity-based approximations for thermal conductivity poor estimators. For this reason, a finite element technique which uses sample microstructure as model input was utilized to determine the conductivity of the carbon phase independent of porosity. Similar modeling techniques were also applied to carbon/copper composite microstructures and predicted conductivities were compared to those determined via experiment.

Johnson, M. T. [Northwestern University, Evanston; Childers, Amanda [Northwestern University, Evanston; Ramírez-Rico, J. [Universidad de Sevilla-CSIC, Spain; Wang, Hsin [ORNL; Faber, K. T. [Northwestern University, Evanston

2013-01-01T23:59:59.000Z

314

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

315

Dual variational principle for a problem of heat conduction in a rectangular plate  

Science Conference Proceedings (OSTI)

In this paper we formulate the dual variational principle for a problem of heat conduction in a rectangular domain, represented by elliptic equation with boundary conditions (Dirichlet-Neumann). The approximate solution for the dual variational problem ... Keywords: dual functional, heat transfer, weak solution

Mioara Boncu?; Dumitru Barac

2010-07-01T23:59:59.000Z

316

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

317

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.

Ibragimov, Nail H

2012-01-01T23:59:59.000Z

318

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

319

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

320

TOPAZ2D heat transfer code users manual and thermal property data base  

Science Conference Proceedings (OSTI)

TOPAZ2D is a two dimensional implicit finite element computer code for heat transfer analysis. This user's manual provides information on the structure of a TOPAZ2D input file. Also included is a material thermal property data base. This manual is supplemented with The TOPAZ2D Theoretical Manual and the TOPAZ2D Verification Manual. TOPAZ2D has been implemented on the CRAY, SUN, and VAX computers. TOPAZ2D can be used to solve for the steady state or transient temperature field on two dimensional planar or axisymmetric geometries. Material properties may be temperature dependent and either isotropic or orthotropic. A variety of time and temperature dependent boundary conditions can be specified including temperature, flux, convection, and radiation. Time or temperature dependent internal heat generation can be defined locally be element or globally by material. TOPAZ2D can solve problems of diffuse and specular band radiation in an enclosure coupled with conduction in material surrounding the enclosure. Additional features include thermally controlled reactive chemical mixtures, thermal contact resistance across an interface, bulk fluid flow, phase change, and energy balances. Thermal stresses can be calculated using the solid mechanics code NIKE2D which reads the temperature state data calculated by TOPAZ2D. A three dimensional version of the code, TOPAZ3D is available. The material thermal property data base, Chapter 4, included in this manual was originally published in 1969 by Art Edwards for use with his TRUMP finite difference heat transfer code. The format of the data has been altered to be compatible with TOPAZ2D. Bob Bailey is responsible for adding the high explosive thermal property data.

Shapiro, A.B.; Edwards, A.L.

1990-05-01T23:59:59.000Z

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.


321

SENSIBLE HEAT STORAGE FOR A SOLAR THERMAL POWER PLANT  

E-Print Network (OSTI)

Calculations for the Heat Exchanger Network Heat-Exchangepower-generation heat exchangers. and storage vessels.and Valves None Heat Exchangers. Distillation Column, Low

Baldwin, Thomas F.

2011-01-01T23:59:59.000Z

322

Thermal Energy Corporation Combined Heat and Power Project  

Science Conference Proceedings (OSTI)

To meet the planned heating and cooling load growth at the Texas Medical Center (TMC), Thermal Energy Corporation (TECO) implemented Phase 1 of a Master Plan to install an additional 32,000 tons of chilled water capacity, a 75,000 ton-hour (8.8 million gallon) Thermal Energy Storage (TES) tank, and a 48 MW Combined Heat and Power (CHP) system. The Department of Energy selected TMC for a $10 million grant award as part of the Financial Assistance Funding Opportunity Announcement, U.S. Department of Energy National Energy Technology, Recovery Act: Deployment of Combined Heat and Power (CHP) Systems, District Energy Systems, Waste Energy Recovery Systems, and Efficiency Industrial Equipment Funding Opportunity Number: DE-FOA-0000044 to support the installation of a new 48 MW CHP system at the TMC located just outside downtown Houston. As the largest medical center in the world, TMC is home to many of the nationâ??s best hospitals, physicians, researchers, educational institutions, and health care providers. TMC provides care to approximately six million patients each year, and medical instruction to over 71,000 students. A medical center the size of TMC has enormous electricity and thermal energy demands to help it carry out its mission. Reliable, high-quality steam and chilled water are of utmost importance to the operations of its many facilities. For example, advanced medical equipment, laboratories, laundry facilities, space heating and cooling all rely on the generation of heat and power. As result of this project TECO provides this mission critical heating and cooling to TMC utilizing a system that is both energy-efficient and reliable since it provides the capability to run on power independent of the already strained regional electric grid. This allows the medical center to focus on its primary mission â?? providing top quality medical care and instruction â?? without worrying about excessive energy costs or the loss of heating and cooling due to the risk of power outages. TECOâ??s operation is the largest Chilled Water District Energy System in the United States. The company used DOEâ??s funding to help install a new high efficiency CHP system consisting of a Combustion Turbine and a Heat Recovery Steam Generator. This CHP installation was just part of a larger project undertaken by TECO to ensure that it can continue to meet TMCâ??s growing needs. The complete efficiency overhaul that TECO undertook supported more than 1,000 direct and indirect jobs in manufacturing, engineering, and construction, with approximately 400 of those being jobs directly associated with construction of the combined heat and power plant. This showcase industrial scale CHP project, serving a critical component of the nationâ??s healthcare infrastructure, directly and immediately supported the energy efficiency and job creation goals established by ARRA and DOE. It also provided an unsurpassed model of a district energy CHP application that can be replicated within other energy intensive applications in the industrial, institutional and commercial sectors.

E. Bruce Turner; Tim Brown; Ed Mardiat

2011-12-31T23:59:59.000Z

323

Universal properties of thermal and electrical conductivity of gauge theory plasmas from holography  

E-Print Network (OSTI)

We propose that for conformal field theories admitting gravity duals, the thermal conductivity is fixed by the central charges in a universal manner. Though we do not have a proof as yet, we have checked our proposal against several examples. This proposal, if correct, allows us to express electrical conductivity in terms of thermodynamical quantities even in the presence of chemical potential.

Sachin Jain

2009-12-14T23:59:59.000Z

324

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

325

Holographic electrical and thermal conductivity in strongly coupled gauge theory with multiple chemical potentials  

E-Print Network (OSTI)

We study transport coefficients of strongly coupled gauge theory in the presence of multiple chemical potential which are dual to rotating D3, M2 and M5 brane. Using the general form of the perturbation equations, we compute DC-electrical conductivity at finite temperature as well as at zero temperature. We also study thermal conductivity for the same class of black holes and show that thermal conductivity and viscosity obeys Wiedemann-Franz like law even in the presence of multiple chemical potential.

Sachin Jain

2009-12-11T23:59:59.000Z

326

Plate Fin Heat Exchanger Model with Axial Conduction and Variable Properties  

Science Conference Proceedings (OSTI)

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

327

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

328

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

Science Conference Proceedings (OSTI)

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

329

Thermal Analysis and Stress Analysis of the Heat-Exchange Pipe Based on ANSYS  

Science Conference Proceedings (OSTI)

ANSYS to be as a finite element analysis software has powerful features in thermal analysis and structural analysis. Based on ANSYS thermal analysis function, this paper selects SOLID90 unit, for thermal analysis on the heat-exchange pipe of heat exchanger ... Keywords: ANSYS, temperature distribution, stress distribution

Fenhua Li; Jian Xing; Yuan Liu

2011-04-01T23:59:59.000Z

330

Thermal analysis of a piston cooling system with reciprocating heat pipes  

SciTech Connect

The reciprocating heat pipe is a very promising technology in engine piston cooling, especially for heavy-duty diesel engines. The concept of the reciprocating heat pipe is verified through the experimental observation of a transparent heat pipe and by thermal testing of a copper/water reciprocating heat pipe. A comparative thermal analysis on the reciprocating heat pipe and gallery cooling systems is performed. The approximate analytical results show that the piston ring groove temperature can be significantly reduced using heat pipe cooling technology, which could contribute to an increase in engine thermal efficiency and a reduction in environmental pollution.

Cao, Y.; Wang, Q. [Florida International Univ., Miami, FL (United States). Dept. of Mechanical Engineering

1995-04-01T23:59:59.000Z

331

Thermal Analysis of the Divertor Primary Heat Transfer System Piping During the Gas Baking Process  

SciTech Connect

A preliminary analysis has been performed examining the temperature distribution in the Divertor Primary Heat Transfer System (PHTS) piping and the divertor itself during the gas baking process. During gas baking, it is required that the divertor reach a temperature of 350 C. Thermal losses in the piping and from the divertor itself require that the gas supply temperature be maintained above that temperature in order to ensure that all of the divertor components reach the required temperature. The analysis described in this report was conducted in order to estimate the required supply temperature from the gas heater.

Yoder Jr, Graydon L [ORNL; Harvey, Karen [ORNL; Ferrada, Juan J [ORNL

2011-02-01T23:59:59.000Z

332

SELF-SIMILAR STRUCTURE OF A HOT MAGNETIZED FLOW WITH THERMAL CONDUCTION  

Science Conference Proceedings (OSTI)

We have explored the structure of a hot magnetized accretion flow with thermal conduction. The importance of thermal conduction in hot accretion flows has been confirmed by observations of the hot gas surrounding Sgr A* and a few other nearby galactic nuclei. For a steady state structure of such accretion flows, a set of self-similar solutions is presented. In this paper, we have actually tried to re-check the solution presented by Abbassi et al. using a physical constraint. In this study, we find that Equation (29) places a new constraint that limits answers presented by Abbassi et al. In that paper, the parameter space, which is established in the new constraint, was plotted. However, the new requirement makes up only a small parameter space with physically acceptable solutions. And now in this paper, we have followed the idea with more effort and tried to find out how thermal conduction influences the structure of the disks in a physical parameter space. We have found that the existence of thermal conduction will lead to the reduction of accretion and radial and azimuthal velocities as well as the vertical thickness of the disk, which is slightly reduced. Moreover, the surface density of the disk will increase when thermal conduction becomes important in hot magnetized flow.

Ghasemnezhad, M.; Khajavi, M. [Department of Physics, School of Sciences, Ferdowsi University of Mashhad, Mashhad, 91775-1436 (Iran, Islamic Republic of); Abbassi, S., E-mail: abbassi@ipm.ir [School of Physics, Damghan University, P.O. Box 36715-364, Damghan (Iran, Islamic Republic of)

2012-05-01T23:59:59.000Z

333

Vacuum Induction Melting Unit Induction heating is a process wherein induced eddy currents heat conductive materials. This heating  

E-Print Network (OSTI)

Vacuum Induction Melting Unit Induction heating is a process wherein induced eddy currents heat can be melted at a time. There are three main parts to the system: chiller, power unit and vacuum unit. The vacuum unit with rotary and diffusion pumps can attain a vacuum of 106 m bar. The power can deliver

Subramaniam, Anandh

334

Thermal protection apparatus  

DOE Patents (OSTI)

An apparatus which thermally protects sensitive components in tools used in a geothermal borehole. The apparatus comprises a Dewar within a housing. The Dewar contains heat pipes such as brass heat pipes for thermally conducting heat from heat sensitive components to a heat sink such as ice.

Bennett, Gloria A. (Los Alamos, NM); Elder, Michael G. (Los Alamos, NM); Kemme, Joseph E. (Albuquerque, NM)

1985-01-01T23:59:59.000Z

335

Thermal protection apparatus  

DOE Patents (OSTI)

The disclosure is directed to an apparatus for thermally protecting sensitive components in tools used in a geothermal borehole. The apparatus comprises a Dewar within a housing. The Dewar contains heat pipes such as brass heat pipes for thermally conducting heat from heat sensitive components such as electronics to a heat sink such as ice.

Bennett, G.A.; Elder, M.G.; Kemme, J.E.

1984-03-20T23:59:59.000Z

336

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

E-Print Network (OSTI)

Uranium-Molybdenum (U-Mo) alloys are of interest to the nuclear engineering community for their potential use as reactor fuel. The addition of molybdenum serves to stabilize the gamma phase of uranium, as well as increasing the melting point of the fuel. Thermal properties of U-Mo alloys have not been fully characterized, especially within the area of partial phase decomposition of the gamma phase of the alloy. Additional data was acquired through this research to expand the characterization data set for U-Mo alloys. The U-Mo alloys used for this research were acquired from the Idaho National Laboratory and consisted of three alloys of nominal 7, 10, and 13 percent molybdenum by weight. The sample pins were formed by vacuum induction melt casting. Once the three sample pins were fabricated and sent to the Fuel Cycle and Materials Laboratory at Texas A&M University, the pins were homogenized and sectioned for heat treatment. Several heat treatments were performed on the samples to induce varying degrees of phase decomposition, and the samples were subsequently sectioned for phase verification and thermal analysis. An Electron Probe Microanalyzer with wavelength dispersive spectroscopy was used to observe the phases in the samples as well as to characterize each phase. The density of each sample was determined using Archimedes method. Finally, a light flash analyzer was used to determine thermal diffusivity of the samples up to 300 degrees C as well as to estimate the thermal conductivity. For U-10Mo, thermal diffusivity increased with increasing phase decomposition from gamma to alpha +U2Mo while U-7Mo saw a flattening of the thermal diffusivity curve with increased phase decomposition.

Creasy, John Thomas

2011-12-01T23:59:59.000Z

337

Review Articles Asymmetric Heat Conduction in the Frenkel-Kontorova Model  

E-Print Network (OSTI)

In this paper, we show numerically that there exist two opposite rectifying effects of heat flux in the one-dimensional two-segment Frenkel-Kontorova chain with certain appropriate parameters. The orientation of the rectifying effects depends on the interfacial coupling strength and the size of the chain under investigation. PACS numbers: 44.10.+i, 05.60.-k, 05.70.Ln Keywords: Frenkel-Kontorova chains, Asymmetric heat conduction

Bambi Hu; Dahai He; Yong Zhang; Lei Yang

2006-01-01T23:59:59.000Z

338

Thermal stress cracking and enhancement of heat extraction from fractured geothermal reservoirs  

DOE Green Energy (OSTI)

The effects of thermal stress cracking, upon heat extraction were studied. Very fundamental approximate analyses were performed to elucidate the mechanics of thermal stress cracking, and the main results are summarized.

Murphy, H.D.

1978-01-01T23:59:59.000Z

339

Transient heat transfer through walls and thermal bridges. numerical modelling: methodology and validation  

Science Conference Proceedings (OSTI)

The current advanced numerical codes for the energy audits carry out 0-dimensional simulation (i.e., one computational node representing the thermal zone), underestimating the effects of thermal bridges on the seasonal heating demand of buildings. The ...

Fabrizio Ascione; Filippo de' Rossi; Nicola Bianco; Giuseppe Peter Vanoli

2012-12-01T23:59:59.000Z

340

Magnetohydrodynamic Simulations of the Formation of Cold Fronts in Clusters of Galaxies including Heat Conduction  

E-Print Network (OSTI)

Recent Chandra observations of clusters of galaxies revealed the existence of a sharp ridge in the X-ray surface brightness where the temperature drops across the front. This front is called the cold front. We present the results of two-dimensional magnetohydrodynamic simulations of the time evolution of a dense subcluster plasma moving in a cluster of galaxies. Anisotropic heat conduction along the magnetic field lines is included. In the models without magnetic fields, the numerical results indicate that the heat conduction from the hot ambient plasma heats the cold dense plasma of the subcluster and diffuses out the cold front. When magnetic fields exist in a cluster of galaxies, however, cold fronts can be maintained because the heat conduction across the magnetic field lines is suppressed. We found that, even when the magnetic fields in a cluster of galaxies are disordered, heat conduction across the front is restricted because the magnetic field lines are stretched along the front. Numerical results reproduced the X-ray intensity distribution observed in the A3667 cluster of galaxies.

Naoki Asai; Naoya Fukuda; Ryoji Matsumoto

2004-04-07T23:59:59.000Z

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.


341

Anomalous heat-kernel decay for random walk among polynomial lower tail random conductances  

E-Print Network (OSTI)

We consider the nearest-neighbor simple random walk on $\\Z^{d}$, $d\\geq 4$, driven by a field of i.i.d. random nearest-neighbor conductances $\\omega_{xy}\\in[0,1]$. Our aim is to derive estimates of the heat-kernel decay in a case where ellipticity assumption is absent. We consider the case of independant conductances with polynomial tail near 0 and obtain for almost every environment an anomalous lower bound on the heat-kernel.

Boukhadra, Omar

2008-01-01T23:59:59.000Z

342

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

343

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

344

Viability Of Hybrid Ground Source Heat Pump System With Solar Thermal Collectors.  

E-Print Network (OSTI)

??This thesis presents a study for examining the viability of hybrid ground source heat pump (GSHP) systems that use solar thermal collectors as the supplemental… (more)

Rad, Farzin M.

2009-01-01T23:59:59.000Z

345

Heat conductivity in small quantum systems: Kubo formula in Liouville space  

E-Print Network (OSTI)

We consider chains consisting of several identical subsystems weakly coupled by various types of next neighbor interactions. At both ends the chain is coupled to a respective heat bath with different temperature modeled by a Lindblad formalism. The temperature gradient introduced by this environment is then treated as an external perturbation. We propose a method to evaluate the heat current and the local temperature profile of the resulting stationary state as well as the heat conductivity in such systems. This method is similar to Kubo techniques used e.g. for electrical transport but extended here to the Liouville space.

Mathias Michel; Jochen Gemmer; Guenter Mahler

2005-03-22T23:59:59.000Z

346

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

SciTech Connect

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

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

2012-03-01T23:59:59.000Z

347

Chandra constraints on the thermal conduction in the intracluster plasma of A2142  

E-Print Network (OSTI)

In this Letter, we use the recent Chandra observation of A2142 reported by Markevitch et al. to put constraints on thermal conduction in the intracluster plasma. We show that the observed sharp temperature gradient requires that classical conductivity has to be reduced at least by a factor of between 250 and 2500. The result provides a direct constraint on an important physical process relevant to the gas in the cores of clusters of galaxies.

S. Ettori; A. C. Fabian

2000-07-26T23:59:59.000Z

348

Hyper-resistivity and electron thermal conductivity due to destroyed magnetic surfaces in axisymmetric plasma equilibria  

Science Conference Proceedings (OSTI)

In order to model the effects of small-scale current-driven magnetic fluctuations in a mean-field theoretical description of a large-scale plasma magnetic field B(x,t), a space and time dependent hyper-resistivity {Lambda}(x,t) can be incorporated into the Ohm's law for the parallel electric field E Dot-Operator B. Using Boozer coordinates, a theoretical method is presented that allows for a determination of the hyper-resistivity {Lambda}({psi}) functional dependence on the toroidal magnetic flux {psi} for arbitrary experimental steady-state Grad-Shafranov axisymmetric plasma equilibria, if values are given for the parallel plasma resistivity {eta}({psi}) and the local distribution of any auxiliary plasma current. Heat transport in regions of plasma magnetic surfaces destroyed by resistive tearing modes can then be modeled by an electron thermal conductivity k{sub e}({psi})=({epsilon}{sub 0}{sup 2}m{sub e}/e{sup 2}){Lambda}({psi}), where e and m{sub e} are the electron charge and mass, respectively, while {epsilon}{sub 0} is the permittivity of free space. An important result obtained for axisymmetric plasma equilibria is that the {psi}{psi}-component of the metric tensor of Boozer coordinates is given by the relation g{sup {psi}{psi}}({psi}){identical_to}{nabla}{psi} Dot-Operator {nabla}{psi}=[{mu}{sub 0}G({psi})][{mu}{sub 0}I({psi})]/{iota}({psi}), with {mu}{sub 0} the permeability of free space, G({psi}) the poloidal current outside a magnetic surface, I({psi}) the toroidal current inside a magnetic surface, and {iota}({psi}) the rotational transform.

Weening, R. H. [Department of Radiologic Sciences, Thomas Jefferson University, 901 Walnut Street, Philadelphia, Pennsylvania 19107-5233 (United States)

2012-06-15T23:59:59.000Z

349

Cooling by Heat Conduction Inside Magnetic Flux Loops and the Moderate Cluster Cooling Flow Model  

E-Print Network (OSTI)

I study non-radiative cooling of X-ray emitting gas via heat conduction along magnetic field lines inside magnetic flux loops in cooling flow clusters of galaxies. I find that such heat conduction can reduce the fraction of energy radiated in the X-ray band by a factor of 1.5-2. This non-radiative cooling joins two other proposed non-radiative cooling processes, which can be more efficient. These are mixing of cold and hot gas, and heat conduction initiated by magnetic fields reconnection between hot and cold gas. These processes when incorporated into the moderate cooling flow model lead to a general cooling flow model with the following ingredients. (1) Cooling flow does occur, but with a mass cooling rate about 10 times lower than in old versions of the cooling flow model. Namely, heating occurs such that the effective age of the cooling flow is much below the cluster age, but the heating can't prevent cooling altogether. (2) The cooling flow region is in a non-steady state evolution. (3) Non-radiative cooling of X-ray emitting gas can bring the model to a much better agreement with observations. (4) The general behavior of the cooling flow gas, and in particular the role played by magnetic fields, make the intracluster medium in cooling flow clusters similar in some aspects to the active solar corona.

Noam Soker

2003-11-02T23:59:59.000Z

350

The Effect of Circuiting Arrangement on the Thermal Performance of Refrigeration Mixtures in Tube-and-Fin Condensing Heat Exchangers  

SciTech Connect

For the pure or azeotropic refrigerants typically used in present air conditioning and refrigeration applications, the refrigerant changes phase at a constant temperature. Thus, the refrigerant circuiting arrangement such as crossfiow, counterfiow, or cross-counterflow, has no effect on the thermal performance. For zeotropic refrigerant mixtures, however, the phase-change occurs over a temperature range, or "glide", and the refrigerant circuiting arrangement, or flow path through the heat exchanger, can affect the thermal performance of both the heat exchangers as well as the overall efficiency of the vapor compression cooling cycle. The effects of tsvo diflerent circuiting arrangements on the thermal performance of a zeotropic retligerant mixture and an almost azeotropic refrigerant mixture in a four-row cross-countertlow heat exchanger arrangement are reported here. The two condensers differ only in the manner of circuiting the refrigerant tubes, where one has refrigerant always flowing downward in the active heat transfer region ("identical order") and the other has refrigerant alternating flow direction in the active heat transfer region ("inverted order"). All other geometric parameters, such as bce are% fin louver geometry, refrigerant tube size and enhancement etc., are the same for both heat exchangers. One refrigerant mixture (R-41OA) un&rgoes a small temperature change ("low glide") during phase change, and the other retligerant mixture (a multi- component proprietary mixture) has a substantial temperature change ("high glide") of approximately 10"C during the phase change process. The overall thermal conductance, two-phase conductance, and pressure drop are presented. For the flow conditions of these tests, which are representative of resi&ntial cooling conditions, inverted order circuiting is more desirable than identical order. The potential thermal advantages of the i&ntical order arrangement for high-glide zeotropic refrigerant mixtures are negated by the increased parasitic refrigerant-side pressure drop utiortunately resulting from tkbrication requirements of the identical order circuiting.

Chen, D.T.; Conklin, J.C.

1999-03-15T23:59:59.000Z

351

Thermal conductivity of silicic tuffs: predictive formalism and comparison with preliminary experimental results  

Science Conference Proceedings (OSTI)

Performance of both near- and far-field thermomechanical calculations to assess the feasibility of waste disposal in silicic tuffs requires a formalism for predicting thermal conductivity of a broad range of tuffs. This report summarizes the available thermal conductivity data for silicate phases that occur in tuffs and describes several grain-density and conductivity trends which may be expected to result from post-emplacement alteration. A bounding curve is drawn that predicts the minimum theoretical matrix (zero-porosity) conductivity for most tuffs as a function of grain density. Comparison of experimental results with this curve shows that experimental conductivities are consistently lower at any given grain density. Use of the lowered bounding curve and an effective gas conductivity of 0.12 W/m{sup 0}C allows conservative prediction of conductivity for a broad range of tuff types. For the samples measured here, use of the predictive curve allows estimation of conductivity to within 15% or better, with one exception. Application and possible improvement of the formalism are also discussed.

Lappin, A. R.

1980-07-01T23:59:59.000Z

352

Enhanced heat extraction from hot-dry-rock geothermal reservoirs due to interacting secondary thermal cracks. Final report  

DOE Green Energy (OSTI)

How the fluid circulating through the main hydraulic fracture and the thermally-induced secondary, growing, interacting cracks affects the time-varying temperature, deformations, stresses, thermal crack geometry, water flow rates through the main and thermal cracks, reservoir coolant outlet temperature, and reservoir thermal power of the cracked geothermal reservoir is investigated. First, a simplified version of the proposed hot-dry-rock reservoir is considered. A closed-form solution of the rock temperature without thermal crack was found and substituted into SAP-IV computer code to calculate the stresses. These stresses being superposed with earth stresses and fluid pressure were used in conjunction with the fracture mechanics criterion to determine the initiation of secondary thermal crack. After the initiation of secondary thermal crack, the rock temperature was then calculated by a two-dimensional heat conduction program AYER. The detailed procedures for carrying out these steps are listed. Solutions developed are applied to studying the time-varying temperature field, thermal stresses and crack geometry produced, and additional heat power generated in the reservoir. Conclusions were discussed and summarized. (MHR)

Hsu, Y.C.

1979-04-01T23:59:59.000Z

353

Implicitly balanced solution of the two-phase flow equations coupled to nonlinear heat conduction  

Science Conference Proceedings (OSTI)

This paper presents the solution of the two-phase flow equations coupled to nonlinear heat conduction using the Jacobian-free Newton-Krylov (JFNK) method which employs a physics-based preconditioner. Computer simulations will demonstrate that the implicitly ... Keywords: implicit, nonlinear, preconditioning, two-phase flow

V. A. Mousseau

2004-10-01T23:59:59.000Z

354

The Active Gravitational Mass of a Heat Conducting Sphere Out of Hydrostatic Equilibrium  

E-Print Network (OSTI)

We obtain an expression for the active gravitational mass of a relativistic heat conducting fluid, just after its departure from hydrostatic equilibrium, on a time scale of the order of relaxation time. It is shown that an increase of a characteristic parameter leads to larger (smaller) values of active gravitational mass of collapsing (expanding) spheres, enhacing thereby the instability of the system.

L. Herrera; A. Di Prisco

1998-10-06T23:59:59.000Z

355

Enhanced thermal conductivity of ethylene glycol with single-walled carbon nanotube inclusions  

E-Print Network (OSTI)

with the Hamilton-Crosser model, the Lu-Lin model, Nan`s effective medium theory and the Hashin-Strikman model to rest of the models. Networking of nanotubes to form a tri-dimensional structure was considered #12;models. Therefore, more studies need to be performed to measure the effective thermal conductivity

Maruyama, Shigeo

356

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

E-Print Network (OSTI)

the thermal conductivity at higher temperatures up to 6%. Computational modeling of SWCNTs in water using of water seeded with single-walled carbon nanotubes (SWCNT) synthesized using the alcohol catalytic this fluid for practical applications. We compare experimental results with existing analytical models

Maruyama, Shigeo

357

SENSIBLE HEAT STORAGE FOR A SOLAR THERMAL POWER PLANT  

E-Print Network (OSTI)

on the Gross Thermal Efficiency of a Solar Power Plant • .and Maintenance* - Net Thermal Efficiency of the Solar PowerMWe Net Thermal Efficiency of the Solar Power Plant,MWe-hr/

Baldwin, Thomas F.

2011-01-01T23:59:59.000Z

358

SENSIBLE HEAT STORAGE FOR A SOLAR THERMAL POWER PLANT  

E-Print Network (OSTI)

STORAGE FOR A SOLAR THERMAL POWER PLANT Thomas F. Baldwin.a central solar thermal power plant. A variety of heliostatSTORAGE FOR A SOLAR THERMAL POWER PLANT Thomas F. Baldwin.

Baldwin, Thomas F.

2011-01-01T23:59:59.000Z

359

SENSIBLE HEAT STORAGE FOR A SOLAR THERMAL POWER PLANT  

E-Print Network (OSTI)

stores or releases thermal energy. This subsystem consistsGas - 436 MW Annual Thermal Energy Absorbed by the Heatof Storage Tanks, m Thermal Energy Stored per Cycle. MW -hr

Baldwin, Thomas F.

2011-01-01T23:59:59.000Z

360

Heat Pump Thermal Distribution Systems, Volumes 1 and 2: Volumes 1 and 2  

Science Conference Proceedings (OSTI)

The thermal distribution system significantly affects the first cost and the operating cost of heat pumps. A detailed study has identified central and zoned systems that promise performance and cost benefits. This report discusses the thermal distribution system's applicability to air-source, ground-coupled, nonazeotropic refrigerant mixture and dual-fuel heat pumps.

1990-06-28T23:59:59.000Z

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

Integrated heat pipe-thermal storage design for a solar receiver. [Constant power source with heat from sun or from storage  

SciTech Connect

Light-weight heat pipe wall elements that incorporate a thermal storage subassembly within the vapor space are being developed as part of the Organic Rankine Cycle Solar Dynamic Power Systems (ORC-SDPS) receiver for the space station application. The operating temperature of he heat pipe elements is in the 770 to 810/sup 0/K range with a design power throughput of 4.8 kW per pipe. The total heat pipe length is 1.9 M. The Rankine cycle boiler heat transfer surfaces are positioned within the heat pipe vapor space, providing a relatively constant temperature input to the vaporizer. The heat pipe design employs axial arteries and distribution wicked thermal storage units with potassium as the working fluid. Stainless steel is used as the containment tube and screen material. Performance predictions for this configuration have been conducted and the design characterized as a function of artery geometry, distribution wick thickness, porosity, pore size, and permeability. Details of the analysis and of fabrication and assembly procedures are presented. 2 refs., 8 figs.

Keddy, E.S.; Sena, J.T.; Woloshun, K.; Merrigan, M.A.; Heidenreich, G.

1986-01-01T23:59:59.000Z

362

Nonequilibrium Temperature and Thermometry in Heat-Conducting Phi-4 Models  

E-Print Network (OSTI)

We analyze temperature and thermometry for simple nonequilibrium heat-conducting models. We show in detail, for both two- and three-dimensional systems, that the ideal gas thermometer corresponds to the concept of a local instantaneous mechanical kinetic temperature. For the Phi-4 models investigated here the mechanical temperature closely approximates the local thermodynamic equilibrium temperature. There is a significant difference between kinetic temperature and the nonlocal configurational temperature. Neither obeys the predictions of extended irreversible thermodynamics. Overall, we find that kinetic temperature, as modeled and imposed by the Nos\\'e-Hoover thermostats developed in 1984, provides the simplest means for simulating, analyzing, and understanding nonequilibrium heat flows.

Wm. G. Hoover; Carol G. Hoover

2008-01-20T23:59:59.000Z

363

Low Thermal Conductivity of RE4Si2O7N2 (RE=Y, Lu): A Systematic ...  

Science Conference Proceedings (OSTI)

The present work shows that identifying new low thermal conductivity ceramics can be realized by a combination approach of first-principles calculation and ...

364

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

E-Print Network (OSTI)

solar thermal systems, which can be used for domestic hot water, space heatingsolar thermal systems, which can be used for domestic hot water, space heating

Marnay, Chris

2010-01-01T23:59:59.000Z

365

Simple procedure for assessing thermal comfort in passive solar heated buildings  

DOE Green Energy (OSTI)

The Fanger thermal comfort equation is linearized and used to develop a procedure for assessing thermal comfort levels in passive solar heated buildings. In order to relate comfort levels in nonuniform environments to uniform conditions, a new thermal index called the equivalent uniform temperature is introduced.

Wray, W.O.

1979-01-01T23:59:59.000Z

366

Structure, thermal expansion and electrical conductivity of Nb-substituted LaCoO{sub 3}  

Science Conference Proceedings (OSTI)

The effect of Nb-substitution in LaCoO{sub 3} has been examined by evaluating the electrical conductivity, thermal expansion and crystal structure of the solid solutions LaCo{sub 1-x}Nb{sub x}O{sub 3} (x=0 to 1/3). It was demonstrated that Nb-substitution in LaCoO{sub 3} was mainly compensated by reduction of Co{sup 3+} to Co{sup 2+}, and that oxidation of Co{sup 2+} could destabilise the solid solution. The ambient crystal structure was shown to transform from rhombohedral R3{sup Macron }c perovskite (x=0) to orthorhombic Pbnm (x=0.15, 0.20) and finally to B-site ordered perovskite P2{sub 1}/n (x=0.25, 1/3) perovskite with increasing Nb-substitution. The thermal expansion of LaCo{sub 1-x}Nb{sub x}O{sub 3} was shown to be strongly depressed with increasing Nb-content, and significantly lower thermal expansion was observed for LaCo{sub 2/3}Nb{sub 1/3}O{sub 3} relative to LaCoO{sub 3}. The electrical conductivity was reduced with increasing Nb-content, and semi-conducting properties was demonstrated for LaCo{sub 1-x}Nb{sub x}O{sub 3} in contrast to the metallic behaviour of pure LaCoO{sub 3} at elevated temperature. The thermal expansion, electrical conductivity and the stability of the materials were discussed with emphasis on Co/Nb ordering, the oxidation state and spin transitions of Co. - Graphical abstract: Substitution of Nb in LaCoO{sub 3} increases the unit cell volume, reduces the symmetry of the unit cell and introduces cation ordering. The chemical substitution leads to suppression of the electronic conductivity and reduces the thermal expansion of the lattice. Highlights: Black-Right-Pointing-Pointer Cation ordering and crystal structure is reported for LaCo{sub x}Nb{sub 1-x}O{sub 3}. Black-Right-Pointing-Pointer Substitution of Nb in LaCoO{sub 3} is compensated by reduction of Co{sup 3+} to Co{sup 2+}. Black-Right-Pointing-Pointer Thermal expansion of LaCoO{sub 3} is reduced by Nb-substitution. Black-Right-Pointing-Pointer Electrical conductivity of LaCoO{sub 3} is reduced by Nb-substitution.

Oygarden, Vegar; Lein, Hilde L. [Department of Materials Science and Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim (Norway); Grande, Tor, E-mail: grande@ntnu.no [Department of Materials Science and Engineering, Norwegian University of Science and Technology, NO-7491 Trondheim (Norway)

2012-08-15T23:59:59.000Z

367

Electron-muon heat conduction in neutron star cores via the exchange of transverse plasmons  

E-Print Network (OSTI)

We calculate the thermal conductivity of electrons and muons kappa_{e-mu} produced owing to electromagnetic interactions of charged particles in neutron star cores and show that these interactions are dominated by the exchange of transverse plasmons (via the Landau damping of these plasmons in nonsuperconducting matter and via a specific plasma screening in the presence of proton superconductivity). For normal protons, the Landau damping strongly reduces kappa_{e-mu} and makes it temperature independent. Proton superconductivity suppresses the reduction and restores the Fermi-liquid behavior kappa_{e-mu} ~ 1/T. Comparing with the thermal conductivity of neutrons kappa_n, we obtain kappa_{e-mu}> kappa_n for T>2 GK in normal matter and for any T in superconducting matter with proton critical temperatures T_c>3e9 K. The results are described by simple analytic formulae.

P. S. Shternin; D. G. Yakovlev

2007-05-14T23:59:59.000Z

368

Estimation of Biomass Heat Storage Using Thermal Infrared Imagery: Application to a Walnut Orchard  

E-Print Network (OSTI)

biomass. The speci?c heat capacity (C p,trunk ), thermalFisch 1986). The speci?c heat capacity of leaves C p,leaf isC p,trunk is the speci?c heat capacity of the trunk, T trunk

Garai, Anirban; Kleissl, Jan; Llewellyn Smith, Stefan G.

2010-01-01T23:59:59.000Z

369

THERMAL PERFORMANCE OF A DUAL-CHANNEL, HELIUM-COOLED, TUNGSTEN HEAT EXCHANGER  

E-Print Network (OSTI)

THERMAL PERFORMANCE OF A DUAL-CHANNEL, HELIUM-COOLED, TUNGSTEN HEAT EXCHANGER Dennis L. Youchison-cooled, refractory heat exchangers are now under consideration for first wall and divertor applications-channel, helium-cooled heat exchanger made almost entirely of tungsten was designed and fabricated by Thermacore

California at Los Angeles, University of

370

Breakdown of the linear approximation in the perturbative analysis of heat conduction in relativistic systems  

E-Print Network (OSTI)

We analyze the effects of thermal conduction in a relativistic fluid just after its departure from spherical symmetry, on a time scale of the order of relaxation time. Using first order perturbation theory, it is shown that, as in spherical systems, at a critical point the effective inertial mass density of a fluid element vanishes and becomes negative beyond that point. The impact of this effect on the reliability of causality conditions is discussed.

L. Herrera; A. Di Prisco; J. Martinez

1998-03-25T23:59:59.000Z

371

Analysis and solution of the ill-posed inverse heat conduction problem  

Science Conference Proceedings (OSTI)

The inverse conduction problem arises when experimental measurements are taken in the interior of a body, and it is desired to calculate temperature and heat flux values on the surface. The problem is shown to be ill-posed, as the solution exhibits unstable dependence on the given data functions. A special solution procedure is developed for the one-dimensional case which replaces the heat conduction equation with an approximating hyperbolic equation. If viewed from a new perspective, where the roles of the spatial and time variables are interchanged, then an initial value problem for the damped wave equation is obtained. Since this formulation is well-posed, both analytic and numerical solution procedures are readily available. Sample calculations confirm that this approach produces consistent, reliable results for both linear and nonlinear problems.

Weber, C.F.

1981-01-01T23:59:59.000Z

372

Hamiltonian Dynamics of Thermostated Systems: Two-Temperature Heat-Conducting phi-4 Chains  

E-Print Network (OSTI)

We consider and compare four Hamiltonian formulations of thermostated mechanics, three of them kinetic, and the other one configurational. Though all four approaches ``work'' at equilibrium, their application to many-body nonequilibrium simulations can fail to provide a proper flow of heat. All the Hamiltonian formulations considered here are applied to the same prototypical two-temperature "phi-4" model of a heat-conducting chain. This model incorporates nearest-neighbor Hooke's-Law interactions plus a quartic tethering potential. Physically correct results, obtained with the isokinetic Gaussian and Nose-Hoover thermostats, are compared with two other Hamiltonian results. The latter results, based on constrained Hamiltonian thermostats, fail correctly to model the flow of heat.

Wm G Hoover; Carol G Hoover

2007-01-20T23:59:59.000Z

373

A blow-up criterion for compressible viscous heat-conductive flows  

E-Print Network (OSTI)

We study an initial boundary value problem for the Navier-Stokes equations of compressible viscous heat-conductive fluids in a 2-D periodic domain or the unit square domain. We establish a blow-up criterion for the local strong solutions in terms of the gradient of the velocity only, which coincides with the famous Beale-Kato-Majda criterion for ideal incompressible flows.

Jiang, Song

2010-01-01T23:59:59.000Z

374

Development of a Test Technique to Determine the Thermal Conductivity of Large Refractory Ceramic Test Specimens  

SciTech Connect

A method has been developed to utilize the High Intensity Infrared lamp located at Oak Ridge National Laboratory for the measurement of thermal conductivity of bulk refractory materials at elevated temperatures. The applicability of standardized test methods to determine the thermal conductivity of refractory materials at elevated temperatures is limited to small sample sizes (laser flash) or older test methods (hot wire, guarded hot plate), which have their own inherent problems. A new method, based on the principle of the laser flash method, but capable of evaluating test specimens on the order of 200 x 250 x 50 mm has been developed. Tests have been performed to validate the method and preliminary results are presented in this paper.

Hemrick, James Gordon [ORNL; Dinwiddie, Ralph Barton [ORNL; Loveland, Erick R [ORNL; Prigmore, Andre L [ORNL

2012-01-01T23:59:59.000Z

375

Dissipative instability of MHD tangential discontinuity in magnetized plasmas with anisotropic viscosity and thermal conductivity.  

E-Print Network (OSTI)

The stability of the MHD tangential discontinuity is studied in compressible plasmas in the presence of anisotropic viscosity and thermal conductivity. The general dispersion equation is derived and solutions to this dispersion equation and stability criteria are obtained for the limiting cases of incompressible and cold plasmas. In these two limiting cases the effect of thermal conductivity vanishes and the solutions are only influenced by viscosity. The stability criteria for viscous plasmas are compared with those for ideal plasmas where stability is determined by the Kelvin-Helmholtz velocity VKH as a threshold for the difference in the equilibrium velocities. Viscosity turns out to have a destabilizing influence when the viscosity coefficient takes different values at the two sides of the discontinuity. Viscosity lowers the threshold velocity V c below the ideal KelvinHelmholtz velocity VKH , so that there is a range of velocities between V c and VKH where the overstability is of ...

Michael Ruderman; Erwin Verwichte; Robertus Erdelyi; Marcel Goossens; Elyiyy

1996-01-01T23:59:59.000Z

376

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,

377

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

E-Print Network (OSTI)

N. et al. , (2007), “Microgrids, An Overview of OngoingSolar Thermal Systems in Microgrids with Combined Heat andSolar Thermal Systems in Microgrids with Combined Heat and

Marnay, Chris

2010-01-01T23:59:59.000Z

378

A STUDY OF ATES THERMAL BEHAVIOR USING A STEADY FLOW MODEL  

E-Print Network (OSTI)

thermal conductivity, Aau heat capacity per unit volume, Ca,thermal conductivity Ac and heat capacity per unit volumeCc• Cw• The heat capacity per unit volume of water is All

Doughty, Christine

2013-01-01T23:59:59.000Z

379

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

380

A Reduced-Boundary-Function Method for Convective Heat Transfer With Axial Heat Conduction and Viscous Dissipation  

Science Conference Proceedings (OSTI)

We introduce a new method of solution for the convective heat transfer under forced laminar flow that is confined by two parallel plates with a distance of 2a or by a circular tube with a radius of a. The advection-conduction equation is first mapped onto the boundary. The original problem of solving the unknown field T(x,r,t) is reduced to seek the solutions of T at the boundary (r = a or r = 0, r is the distance from the centerline shown in Fig. 1), i.e., the boundary functions T{sub a}(x,t) {triple_bond} T(x,r=a,t) and/or T{sub 0}(x,t) {triple_bond} T(x,r=0,t). In this manner, the original problem is significantly simplified by reducing the problem dimensionality from 3 to 2. The unknown field T(x,r,t) can be eventually solved in terms of these boundary functions. The method is applied to the convective heat transfer with uniform wall temperature boundary condition and with heat exchange between flowing fluids and its surroundings that is relevant to the geothermal applications. Analytical solutions are presented and validated for the steady-state problem using the proposed method.

Zhijie Xu

2012-07-01T23:59:59.000Z

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.


381

A Reduced-Boundary-Function Method for Convective Heat Transfer with Axial Heat Conduction and Viscous Dissipation  

Science Conference Proceedings (OSTI)

We introduce a method of solution for the convective heat transfer under forced laminar flow that is confined by two parallel plates with a distance of 2a or by a circular tube with a radius of a. The advection-conduction equation is first mapped onto the boundary. The original problem of solving the unknown field is reduced to seek the solutions of T at the boundary (r=a or r=0, r is the distance from the centerline shown in Fig. 1), i.e. the boundary functions and/or . In this manner, the original problem is significantly simplified by reducing the problem dimensionality from 3 to 2. The unknown field can be eventually solved in terms of these boundary functions. The method is applied to the convective heat transfer with uniform wall temperature boundary condition and with heat exchange between flowing fluids and its surroundings that is relevant to the geothermal applications. Analytical solutions are presented and validated for the steady state problem using the proposed method.

Xu, Zhijie

2012-07-01T23:59:59.000Z

382

Spatial and temporal variations in streambed hydraulic conductivity quantified with time-series thermal methods  

E-Print Network (OSTI)

conductivity Streambed seepage Heat as a tracer Surface water­ground water interaction Pajaro River s u m m a r was 62 m3 s�1 , with most of the loss occurring along the lower part of the experimental reach. Point and with time, with greater seepage occurring along the lower part of the reach and during the summer and fall

Fisher, Andrew

383

SENSIBLE HEAT STORAGE FOR A SOLAR THERMAL POWER PLANT  

E-Print Network (OSTI)

to electricity. Pumped-hydroelectric storage and batteryis pumped between the heat exchangers and the storage unit.

Baldwin, Thomas F.

2011-01-01T23:59:59.000Z

384

Thermal diffusivity and thermal conductivity of sintered UO2 and UO2-Gd2O3. Technical report  

SciTech Connect

The thermal diffusivity was measured using the laser flash method on sintered uranium dioxide (O/U=2.003, density=10.48X10 kg/m, from 300 to 2773 K), and urania and gadolinia mixed fuel (2,4 and 6 Wt% Gd2O3 content, from 600 to 1850 K). An equation was suggested for near-stoichiometric uranium dioxide over the temperature range 500-3100 K: K=(1-aP)(1/(A+BT)+DTxexp(-E/kT)x(1+H(E/kT+2)(sup 2))), where K in W/(m)(K), P is the fraction of porosity, a=2.74-5.8X10(sup 4-)T, A=3.68X10(sup 2-)(m)(K)/W, B=2.25X10(sup 4-)m/W, D=5.31X10(sup 3-)W/mXK2, H=0.264, E=1.15 ev, k is the Boltzmann constant. The thermal conductivity of UO2-Gd2O3 samples as a function of temperature and Gd2O3 content, X, could be expressed by phonon conduction; K=1/(A+BT) in the temperature range from 600 to 1700 K, where A=2.50 X+0.044(m)(K)/W.

Ying, S.; Ji, Z.

1988-01-01T23:59:59.000Z

385

The Braginskii model of the Rayleigh-Taylor instability. I. Effects of self-generated magnetic fields and thermal conduction in two dimensions  

E-Print Network (OSTI)

(abridged) There exists a substantial disagreement between computer simulation results and high-energy density laboratory experiments of the Rayleigh-Taylor instability Kuranz et al. (2010). We adopt the Braginskii formulation for transport in hot, dense plasma, implement and verify the additional physics modules, and conduct a computational study of a single-mode RTI in two dimensions with various combinations of the newly implemented modules. We find that magnetic fields reach levels on the order of 11 MG in the absence of thermal conduction. We observe denting of the RT spike tip and generation of additional higher order modes as a result of these fields. Contrary to interpretation presented in earlier work Nishiguchi (2002), the additional mode is not generated due to modified anisotropic heat transport effects but due to dynamical effect of self-generated magnetic fields. The main effects of thermal conduction are a reduction of the RT instability growth rate (by about 20% for conditions considered here)...

Modica, Frank; Zhiglo, Andrey

2013-01-01T23:59:59.000Z

386

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 of underground water has also been considered. The economics of the heat pump and other cooling and heating sources has been compared and then several simple methods to improve the thermal economics of the underground water heat pump system have been put forward.

Zhang, W.; Lin, B.

2006-01-01T23:59:59.000Z

387

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

388

Universal Heat Conduction in the Iron Arsenide Superconductor KFe2As2: Evidence of a d-Wave State  

SciTech Connect

The thermal conductivity ? of the iron arsenide superconductor KFe2As2 was measured down to 50 mK for a heat current parallel and perpendicular to the tetragonal c axis. A residual linear term at T?0, ?0/T is observed for both current directions, confirming the presence of nodes in the superconducting gap. Our value of ?0/T in the plane is equal to that reported by Dong et al. [ Phys. Rev. Lett. 104 087005 (2010)] for a sample whose residual resistivity ?0 was 10 times larger. This independence of ?0/T on impurity scattering is the signature of universal heat transport, a property of superconducting states with symmetry-imposed line nodes. This argues against an s-wave state with accidental nodes. It favors instead a d-wave state, an assignment consistent with five additional properties: the magnitude of the critical scattering rate ?c for suppressing Tc to zero; the magnitude of ?0/T, and its dependence on current direction and on magnetic field; the temperature dependence of ?(T).

Reid, J.-Ph.; Tanatar, Makariy A.; Juneau-Fecteau, A.; Gordon, R.T.; Rene de Cotret, S.; Doiron-Leyraud, N.; Saito, T.; Fukazawa, H.; Kohori, Y.; Kihou, K.; Lee, C.H.; Iyo, A.; Eisaki, H.; Prozorov, Ruslan; Taillefer, Louis

2012-08-21T23:59:59.000Z

389

Table 8.3c Useful Thermal Output at Combined-Heat-and-Power ...  

U.S. Energy Information Administration (EIA)

Table 8.3c Useful Thermal Output at Combined-Heat-and-Power Plants: Commercial and Industrial Sectors, 1989-2011 (Subset of Table 8.3a; Trillion ...

390

Heat and Momentum Fluxes Induced by Thermal Inhomogeneities with and without Large-Scale Flow  

Science Conference Proceedings (OSTI)

The authors Present an analytical evaluation of the vertical heat and momentum fluxes associated with mesoscale flow generated by periodic and isolated thermal inhomogeneities within the convective boundary layer (CBL). The influence of larger-...

G. A. Dalu; R. A. Pielke; M. Baldi; X. Zeng

1996-11-01T23:59:59.000Z

391

Table 8.3b Useful Thermal Output at Combined-Heat-and-Power ...  

U.S. Energy Information Administration (EIA)

Table 8.3b Useful Thermal Output at Combined-Heat-and-Power Plants: Electric Power Sector, 1989-2011 (Subset of Table 8.3a; Trillion Btu)

392

Analysis on electro-thermal property of micro-bubble generator using carbon nanotube heating elements  

Science Conference Proceedings (OSTI)

Localized high temperature due to Joule heating in Carbon Nanotubes (CNTs) can generate micron-sized bubbles. Electro-thermal property of CNTs-based microbubble generator is characterized by finite element analysis in this paper. Water circumstance with ...

Wenli Zhou; Sanping Wan; Chao Zhu

2009-01-01T23:59:59.000Z

393

Spherical collapse of a heat conducting fluid in higher dimensions without horizon  

E-Print Network (OSTI)

We consider a scenario where the interior spacetime,described by a heat conducting fluid sphere is matched to a Vaidya metric in higher dimensions.Interestingly we get a class of solutions, where following heat radiation the boundary surface collapses without the appearance of an event horizon at any stage and this happens with reasonable properties of matter field.The non-occurrence of a horizon is due to the fact that the rate of mass loss exactly counterbalanced by the fall of boundary radius.Evidently this poses a counter example to the so-called cosmic censorship hypothesis.Two explicit examples of this class of solutions are also given and it is observed that the rate of collapse is delayed with the introduction of extra dimensions.The work extends to higher dimensions our previous investigation in 4D.

A. banerjee; S. Chatterjee

2004-06-08T23:59:59.000Z

394

Spherical collapse of a heat conducting fluid in higher dimensions without horizon  

E-Print Network (OSTI)

We consider a scenario where the interior spacetime,described by a heat conducting fluid sphere is matched to a Vaidya metric in higher dimensions.Interestingly we get a class of solutions, where following heat radiation the boundary surface collapses without the appearance of an event horizon at any stage and this happens with reasonable properties of matter field.The non-occurrence of a horizon is due to the fact that the rate of mass loss exactly counterbalanced by the fall of boundary radius.Evidently this poses a counter example to the so-called cosmic censorship hypothesis.Two explicit examples of this class of solutions are also given and it is observed that the rate of collapse is delayed with the introduction of extra dimensions.The work extends to higher dimensions our previous investigation in 4D.

Banerjee, A

2004-01-01T23:59:59.000Z

395

SENSIBLE HEAT STORAGE FOR A SOLAR THERMAL POWER PLANT  

E-Print Network (OSTI)

Dry-Cooling Tower • Power-Generation Subsystem Summary AnGas-Circulation Subsystem The Power-Generation Subsystem Theinsulating plant piping. power-generation heat exchangers.

Baldwin, Thomas F.

2011-01-01T23:59:59.000Z

396

Phase Change Materials for Enhancing Heat Transfer in Thermal ...  

Science Conference Proceedings (OSTI)

One of the main issues with using phase change materials is that solidification often reduces total heat transfer, reducing the efficiency of the storage system.

397

Thermal stability of proton conducting acid doped polybenzimidazole in simulated fuel cell environments  

Science Conference Proceedings (OSTI)

Recently, polybenzimidazole membrane doped with phosphoric acid (PBI) was found to have promising properties for use as a polymer electrolyte in a high temperature (ca. 150 to 200 C) proton exchange membrane direct methanol fuel cell. However, operation at 200 C in strongly reducing and oxidizing environments introduces concerns of the thermal stability of the polymer electrolyte. To simulate the conditions in a high temperature fuel cell, PBI samples were loaded with fuel cell grade platinum black, doped with ca. 480 mole percent phosphoric acid (i.e., 4.8 H{sub 3}PO{sub 4} molecules per PBI repeat unit) and heated under atmospheres of either nitrogen, 5% hydrogen, or air in a thermal gravimetric analyzer. The products of decomposition were taken directly into a mass spectrometer for identification. In all cases weight loss below 400 C was found to be due to loss of water. Judging from the results of these tests, the thermal stability of PBI is more than adequate for use as a polymer electrolyte in a high temperature fuel cell.

Samms, S.R.; Wasmus, S.; Savinell, R.F. [Case Western Reserve Univ., Cleveland, OH (United States)

1996-04-01T23:59:59.000Z

398

Electrically heated liquid tank employing heat pipe heat transfer means  

SciTech Connect

The heating apparatus for applying heat to the interior of a chamber includes a modular, removable, electrical, heat-producing unit and a heat pipe mountable in a wall of the chamber with one end of the pipe arranged to receive heat from the electrical heat producing unit exterior of the housing and with another end of the pipe constructed and arranged to apply heat to the medium within the chamber. The heat pipe has high conductivity with a low temperature differential between the ends thereof and the heat producing unit includes an electric coil positioned about and removably secured to the one end of the heat pipe. The electric coil is embedded in a high thermal conducitivity, low electrical conductivity filler material which is surrounded by a low thermal conductivity insulating jacket and which is received around a metal core member which is removably secured to the one end of the heat pipe.

Shutt, J.R.

1978-12-26T23:59:59.000Z

399

Waste Heat Recovery System: Lightweight Thermal Energy Recovery (LIGHTER) System  

SciTech Connect

Broad Funding Opportunity Announcement Project: GM is using shape memory alloys that require as little as a 10°C temperature difference to convert low-grade waste heat into mechanical energy. When a stretched wire made of shape memory alloy is heated, it shrinks back to its pre-stretched length. When the wire cools back down, it becomes more pliable and can revert to its original stretched shape. This expansion and contraction can be used directly as mechanical energy output or used to drive an electric generator. Shape memory alloy heat engines have been around for decades, but the few devices that engineers have built were too complex, required fluid baths, and had insufficient cycle life for practical use. GM is working to create a prototype that is practical for commercial applications and capable of operating with either air- or fluid-based heat sources. GM’s shape memory alloy based heat engine is also designed for use in a variety of non-vehicle applications. For example, it can be used to harvest non-vehicle heat sources, such as domestic and industrial waste heat and natural geothermal heat, and in HVAC systems and generators.

2010-01-01T23:59:59.000Z

400

Heat extraction for the CSPonD thermal storage unit  

E-Print Network (OSTI)

Three coiled tube heat exchanger prototypes were designed to extract heat from containers holding 0.5 kg, 2.3 kg, and 10.5 kg of Sodium Nitrate-Potassium Nitrate salt. All of the prototypes were left with an open surface ...

Rojas, Folkers Eduardo

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.


401

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); Ivanov, Ilya N. (Knoxville, TN); Puretzky,; Alexander A. (Knoxville, TN)

2010-07-27T23:59:59.000Z

402

Experimental investigation of size effect on thermal conductivity for ultra-thin amorphous poly(methyl methacrylate) (PMMA) films  

E-Print Network (OSTI)

An investigation was conducted to determine whether a “size effect” phenomenon for one particular thermophysical property, thermal conductivity, actually exists for amorphous poly(methyl methacrylate) (PMMA) films with thicknesses ranging from 40 nm to 2 ?m. This was done by using a non-contact, non-invasive, in-situ Transient Thermo-Reflectance (TTR) laser based technique. The results demonstrated that the intrinsic thermal conductivity of a 40 nm PMMA film deposited on native oxide of silicon increases by a factor of three over bulk PMMA values, and a distinct increase in the thermal conductivity of PMMA film was observed in ultra-thin (sub 100 nm) films. This confirmed the importance of film thickness for the through-plane thermal conductivity value of PMMA film on native oxide of silicon.

Kim, Ick Chan

2007-05-01T23:59:59.000Z

403

The Effect of Latent Heat Release on the Evolution of a Warm Occluded Thermal Structure  

Science Conference Proceedings (OSTI)

The effect of latent heat release on the development of the occluded thermal structure in a major winter storm is examined through comparison of full physics (FP) and no-latent-heat-release (NLHR) simulations of the event performed using the ...

Derek J. Posselt; Jonathan E. Martin

2004-02-01T23:59:59.000Z

404

Neutronic and thermal design considerations for heat-pipe reactors  

SciTech Connect

SABRE (Space-Arena Baseline Reactor) is a 100-kW/sub e/, heat-pipe-cooled, beryllium-reflected, fast reactor that produces heat at a temperature of 1500/sup 0/K and radiatively transmits it to high-temperature thermoelectric (TE) conversion elements. The use of heat pipes for core heat removal eliminates single-point failure mechanisms in the reactor cooling system, and provides minimal temperature drop radiative coupling to the TE array, as well as automatic, self-actuating removal of reactor afterheat. The question of how the failure of a fuel module heat pipe will affect neighboring fuel modules in the core is discussed, as is fission density peaking that occurs at the core/reflector interface. Results of neutronic calculations of the control margin available are described. Another issue that is addressed is that of helium generation in the heat pipes from neutron reactions in the core with the heat pipe fluid. Finally, the growth potential of the SABRE design to much higher powers is examined.

Ranken, W.A.; Koenig, D.R.

1983-01-01T23:59:59.000Z

405

Strong Evidence of Normal Heat Conduction in a one-Dimensional Quantum System  

E-Print Network (OSTI)

We investigate how the normal energy transport is realized in one-dimensional quantum systems using a quantum spin system. The direct investigation of local energy distribution under thermal gradient is made using the quantum master equation, and the mixing properties and the convergence of the Green-Kubo formula are investigated when the number of spin increases. We find that the autocorrelation function in the Green-Kubo formula decays as $\\sim t^{-1.5}$ to a finite value which vanishes rapidly with the increase of the system size. As a result, the Green-Kubo formula converges to a finite value in the thermodynamic limit. These facts strongly support the realization of Fourier heat law in a quantum system.

Keiji Saito

2002-12-11T23:59:59.000Z

406

Cause of super-thermal electron heating during magnetotail reconnection  

E-Print Network (OSTI)

[1] We present a candidate mechanism for the energization of super-thermal electrons during magnetic reconnection in the Earth's magnetotail. By analyzing in-situ measurements of electron distribution functions we characterize ...

Egedal-Pedersen, Jan

407

Thermal Response of Tritiated Co-deposits from JET and TFTR to Transient Heat Pulses  

Science Conference Proceedings (OSTI)

High heat flux interactions with plasma-facing components have been studied at microscopic scales. The beam from a continuous wave neodymium laser was scanned at high speed over the surface of graphite and carbon fiber composite tiles that had been retrieved from TFTR (Tokamak Fusion Test Reactor) and JET (Joint European Torus) after D-T plasma operations. The tiles have a surface layer of amorphous hydrogenated carbon that was co-deposited during plasma operations, and laser scanning has released more than 80% of the co-deposited tritium. The temperature rise of the co-deposit was much higher than that of the manufactured material and showed an extended time history. The peak temperature varied dramatically (e.g., 1,436 C compared to >2,300 C), indicating strong variations in the thermal conductivity to the substrate. A digital microscope imaged the co-deposit before, during, and after the interaction with the laser and revealed 100-micron scale hot spots during the interaction. Heat pulse durations of order 100 ms resulted in brittle destruction and material loss from the surface, whilst a duration of =10 ms showed minimal changes to the co-deposit. These results show that reliable predictions for the response of deposition areas to off-normal events such as ELMs (edge-localized modes) and disruptions in next-step devices need to be based on experiments with tokamak generated co-deposits.

C.H. Skinner; N. Bekrisl; J.P. Coad; C.A. Gentile; A. Hassanein; R. Reiswig; S. Willms

2002-05-30T23:59:59.000Z

408

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

409

ESTIMATION OF IN-SITU THERMAL CONDUCTIVITIES FROM TEMPERATURE GRADIENT MEASUREMENTS  

E-Print Network (OSTI)

By analyzing the heat transfer process inside the tubing andnatural convection heat transfer process, three equationsis the dominant heat transfer process during shut-in, the

Hoang, V.T.

2010-01-01T23:59:59.000Z

410

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

E-Print Network (OSTI)

flow in geologic heat pipes, Journal of Contaminantwhat could be called “heat-pipe” signatures, a flat zone (atpervasive evidence of these heat-pipe signatures [Birkholzer

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

2008-01-01T23:59:59.000Z

411

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

E-Print Network (OSTI)

vicinity of the heat source, and rock temperature exceededand the dry rock near the heat source. The other differencesources, heat transfer takes place through the wet rock (see

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

2008-01-01T23:59:59.000Z

412

Heat exchanger device and method for heat removal or transfer  

Science Conference Proceedings (OSTI)

Systems and methods for a forced-convection heat exchanger are provided. In one embodiment, heat is transferred to or from a thermal load in thermal contact with a heat conducting structure, across a narrow air gap, to a rotating heat transfer structure immersed in a surrounding medium such as air.

Koplow, Jeffrey P. (San Ramon, CA)

2012-07-24T23:59:59.000Z

413

System for thermal energy storage, space heating and cooling and power conversion  

DOE Patents (OSTI)

An integrated system for storing thermal energy, for space heating and cong and for power conversion is described which utilizes the reversible thermal decomposition characteristics of two hydrides having different decomposition pressures at the same temperature for energy storage and space conditioning and the expansion of high-pressure hydrogen for power conversion. The system consists of a plurality of reaction vessels, at least one containing each of the different hydrides, three loops of circulating heat transfer fluid which can be selectively coupled to the vessels for supplying the heat of decomposition from any appropriate source of thermal energy from the outside ambient environment or from the spaces to be cooled and for removing the heat of reaction to the outside ambient environment or to the spaces to be heated, and a hydrogen loop for directing the flow of hydrogen gas between the vessels. When used for power conversion, at least two vessels contain the same hydride and the hydrogen loop contains an expansion engine. The system is particularly suitable for the utilization of thermal energy supplied by solar collectors and concentrators, but may be used with any source of heat, including a source of low-grade heat.

Gruen, Dieter M. (Downers Grove, IL); Fields, Paul R. (Chicago, IL)

1981-04-21T23:59:59.000Z

414

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

E-Print Network (OSTI)

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

Zuo, Yanjia

2010-01-01T23:59:59.000Z

415

Experimental Determination of the Effect of Reactor Radiation on the Thermal Conductivity of Uranium-Impregnated Graphite  

SciTech Connect

Experiments are described in which the change in thermal conductivity of U-impregnated graphite under neutron irradiation was measured. Thermal resistivities relative to the thermal resistivity of undamaged impregnated graphite are reorted as functions of exposure. From applications of the expermental results to the North American Aviation low-power research reactor the peak tem. of the core is determined for a given reactor power and time of operation.

Hetrick, D.L.; McCarty, W.K.; Steele, G.N.; Brown, M.S.; Clark, E.V.; Holmes, F.R.; Howard, D.F.; McElroy, W.N.; Shields, B.L.

1953-01-06T23:59:59.000Z

416

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.

Biehs, Svend-Age

2011-01-01T23:59:59.000Z

417

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

418

Visualization of heat transport using dimensionless heatfunction for natural convection and conduction in an enclosure with thick solid ceiling  

Science Conference Proceedings (OSTI)

A conjugate conduction-(natural)convection problem is numerically studied in order to present the application of dimensionless heatfunction for entire computational domain including solid and fluid regions in an enclosure with thick solid ceiling. The ... Keywords: Conjugate heat transfer, Dimensionless heatfunction, Heat transport, Heatline, Natural convection

Moghtada Mobedi; Hakan F. Oztop

2008-11-01T23:59:59.000Z

419

(Thermal energy storage technologies for heating and cooling applications)  

DOE Green Energy (OSTI)

Recent results from selected TES research activities in Germany and Sweden under an associated IEA annex are discussed. In addition, several new technologies for heating and cooling of buildings and automobiles were reviewed and found to benefit similar efforts in the United states. Details of a meeting with Didier-Werke AG, a leading German ceramics manufacturer who will provide TES media necessary for the United States to complete field tests of an advanced high temperature latent heat storage material, are presented. Finally, an overview of the December 1990 IEA Executive Committee deliberations on TES is presented.

Tomlinson, J.J.

1990-12-19T23:59:59.000Z

420

Ground surface temperature reconstructions: Using in situ estimates for thermal conductivity acquired with a fiber-optic distributed thermal perturbation sensor  

Science Conference Proceedings (OSTI)

We have developed a borehole methodology to estimate formation thermal conductivity in situ with a spatial resolution of one meter. In parallel with a fiber-optic distributed temperature sensor (DTS), a resistance heater is deployed to create a controlled thermal perturbation. The transient thermal data is inverted to estimate the formation's thermal conductivity. We refer to this instrumentation as a Distributed Thermal Perturbation Sensor (DTPS), given the distributed nature of the DTS measurement technology. The DTPS was deployed in permafrost at the High Lake Project Site (67 degrees 22 minutes N, 110 degrees 50 minutes W), Nunavut, Canada. Based on DTPS data, a thermal conductivity profile was estimated along the length of a wellbore. Using the thermal conductivity profile, the baseline geothermal profile was then inverted to estimate a ground surface temperature history (GSTH) for the High Lake region. The GSTH exhibits a 100-year long warming trend, with a present-day ground surface temperature increase of 3.0 {+-} 0.8 C over the long-term average.

Freifeld, B.M.; Finsterle, S.; Onstott, T.C.; Toole, P.; Pratt, L.M.

2008-10-10T23:59:59.000Z

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

Numerical Simulation of Thermal-Solid Coupling to Coal-Rock during the Process of Heat Injection Mine for CBM  

Science Conference Proceedings (OSTI)

For gaining effective influence radius of heat injection mine for CBM (Coal Bed Methane) and influence rules of permeability under the condition of temperature and effective stress, heat transfer and elastic mechanics theory combined, hooker law of thermal ... Keywords: heat injection, thermal-solid coupling, numerical simulation, effective influence radius, permeability

Xin Le Yang; Yong Li Zhang

2010-12-01T23:59:59.000Z

422

Cross-plane lattice and electronic thermal conductivities of ErAs : InGaAs/InGaAlAs superlattices  

E-Print Network (OSTI)

should be noted that the lattice thermal conductivity should88, 242107 ?2006? Cross-plane lattice and electronic thermalWe studied the cross-plane lattice and electronic thermal

2006-01-01T23:59:59.000Z

423

Method of making improved gas storage carbon with enhanced thermal conductivity  

DOE Patents (OSTI)

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

Burchell, Timothy D [Oak Ridge, TN; Rogers, Michael R [Knoxville, TN

2002-11-05T23:59:59.000Z

424

Method of making improved gas storage carbon with enhanced thermal conductivity  

SciTech Connect

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

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

2002-01-01T23:59:59.000Z

425

Characterization of the Ground Thermal Response to Heating by a Deep Vertical Borehole Heat Exchanger.  

E-Print Network (OSTI)

??This thesis presents an experiment and an analysis that evaluates some of the long-standing assumptions in deep vertical borehole ground heat exchanger (GHX) theory. These… (more)

Olfman, Maeir Zalman

2012-01-01T23:59:59.000Z

426

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

E-Print Network (OSTI)

internal cavities the heat transfer process is more complex,heat transfer in these “insulated” zones could be used in the design process

Gustavsen, Arild

2009-01-01T23:59:59.000Z

427

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&GSHP system can serve as cold energy thermal storage at night, produce chilled water in the daytime in summer and provide hot water for heating in winter. This is followed by its schematic and characteristic description. Then the various operation modes of such system according to different operational strategies are demonstrated in sequence. The system, firstly seen in open literature, is energy-saving, environmental-friendly and promising in the field of air-conditioning systems, and will help solve the problems currently existing with the GSHP system and ITES air conditioning system.

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

2006-01-01T23:59:59.000Z

428

ESTIMATION OF IN-SITU THERMAL CONDUCTIVITIES FROM TEMPERATURE GRADIENT MEASUREMENTS  

E-Print Network (OSTI)

where: pc v • phonon heat capacity, c• phonon velocity,fluid density, the specific heat capacity of the fluid. Thean l8cm Values of heat capacities diameter casing for three

Hoang, V.T.

2010-01-01T23:59:59.000Z

429

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

Science Conference Proceedings (OSTI)

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

430

Damp-Heat Induced Degradation of Transparent Conducting Oxides for Thin-Film Solar Cells: Preprint  

DOE Green Energy (OSTI)

The stability of intrinsic and Al-doped single- and bi-layer ZnO for thin-film CuInGaSe2 solar cells, along with Al-doped Zn1-xMgxO alloy and Sn-doped In2O3 (ITO) and F-doped SnO2, was evaluated by direct exposure to damp heat (DH) at 85oC and 85% relative humidity. The results show that the DH-induced degradation rates followed the order of Al-doped ZnO and Zn1-xMgxO >> ITO > F:SnO2. The degradation rates of Al:ZnO were slower for films of higher thickness, higher substrate temperature in sputter-deposition, and with dry-out intervals. As inferred from the optical micro-imaging showing the initiation and propagation of degrading patterns and regions, the degradation behavior appears similar for all TCOs, despite the obvious difference in the degradation rate. A degradation mechanism is proposed to explain the temporal process involving thermal hydrolysis.

Pern, F. J.; Noufi, R.; Li, X.; DeHart, C.; To, B.

2008-05-01T23:59:59.000Z

431

Assessment of Latent Heat Reservoirs for Thermal Management of QCW Laser Diodes  

SciTech Connect

There is great interest in improving the thermal management of laser diodes intended for use as pumps in inertial confinement fusion systems. Laser diode power is currently constrained by heat dissipation in the diodes. Diodes typically dissipate a quantity of heat that is comparable to their optical power output. This heating of the diode junction causes a thermal rollover that prevents the output power from scaling linearly with current drive, and also results in reliability limits due to catastrophic failure at diode mirror facets. For the pulsed, quasi-continuous wave (QCW) operating mode employed for LIFE and certain DOD applications, {approx}5 kW/cm{sup 2} of heat must be removed on timescales of {approx}100{micro}s, which is determined by thermal paths located within {approx}200 {micro}m of the laser junction. For these reasons, QCW thermal management is extremely challenging. Reducing the diode junction temperature enables more efficient operation, reduced thermal chirp, and operation at higher output power without compromised reliability - which improves the diode costs as measured in $/W. We have proposed the use of latent heat reservoirs to improve thermal management of diodes used in pulsed, quasi-continuous wave (QCW) operation. Our basic concept involves placement of a reservoir of low-melting-point metal within a few hundred microns of the laser junction, as in Fig. 1-1. This metal's latent heat of fusion maintains a nearly constant temperature (like a cold plate) in the very near vicinity of the diode junction. This cold reservoir creates large thermal gradients, which in turn are anticipated to drive a large heat flow from the diode. In contrast, conventional QCW devices rely on thermal diffusion into a large solid mass which cannot be held at a fixed temperature, which significantly limits the thermal extraction. Our operational concept involves phase changes within the reservoir during every QCW pulse. During the early portion of the pulse, heating of the diode and its surrounding material initiates melting within the latent heat reservoir. This phase change results in a near-constant reservoir temperature that facilitates heat transfer. During the long ({approx}100 ms) time between QCW pulses, the reservoir metal resolidifies. A simple back-of-the-envelope calculation based on Gallium metal shows that a 50 {micro}m thick Gallium reservoir is sufficient to absorb all heat generated by a 350 {micro}s pulse at 5 kW/cm{sup 2}. While this calculation shows that a latent heat reservoir can provide sufficient capacity to handle the magnitude of heat generated, it does not address the transient change in the diode junction temperature, which depends on details the heat flow into and through the reservoir. For this reason, we undertook a set of numerical experiments to quantitatively assess the impact of latent heat reservoirs on junction temperature. This report documents the results of these simulations.

Deri, B; Kotovsky, J; Spadaccini, C

2010-03-15T23:59:59.000Z

432

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 scheme in economical, technical, and environmental aspects, it is determined that the scheme of the groundwater source heat pump has better energy efficiency than others. The GHPWTS can take full advantage of the heat source from groundwater and benefit of electricity difference pricing during a day. Its character is a combination of a strength and another strength. It is the lowest cycle cost of all chide and heat source schemes. The GHPWTS has the best economic benefit and runs stably and reliably. Its advantage is clearly compared with other schemes. There is a real value for the project that is similar to the characteristic of this project and the condition of the water source.

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

2006-01-01T23:59:59.000Z

433

Troubleshooting Guide for Thermal Transients in Heat Recovery Steam Generators (HRSG)  

Science Conference Proceedings (OSTI)

Over the period 2000-2009 EPRI developed ten reports and guidance documents on Heat Recovery Steam Generator (HRSG) thermal transients. Collectively, these documents provide the information required to identify, address, and minimize thermal transients in HRSG superheaters, reheaters, economizers, and evaporators. This summary report offers an overview of this EPRI work on HRSG transients organized to guide the reader to pertinent sections in the original reports and facilitate troubleshooting.

2009-11-09T23:59:59.000Z

434

Design, cost, and performance comparisons of several solar thermal systems for process heat. Volume III. Receivers  

DOE Green Energy (OSTI)

The receiver subsystem converts reflected solar radiation into thermal power by heating a working fluid. The objective of the task described was to estimate the cost and performance of the receiver subsystem for parabolic troughs, parabolic dishes, and central receivers over a wide range of temperatures and power levels for thermal power applications. This volume presents the fundamental design philosophy employed, the constraints identified, the tradeoffs performed and the cost and performance results obtained for each receiver in the study matrix.

Woodard, J.B. Jr.

1981-03-01T23:59:59.000Z

435

Solar heat pipe testing of the Stirling thermal motors 4-120 Stirling engine  

DOE Green Energy (OSTI)

Stirling-cycle engines have been identified as a promising technology for the conversion of concentrated solar energy into usable electrical power. A 25kW electric system takes advantage of existing Stirling-cycle engines and existing parabolic concentrator designs. In previous work, the concentrated sunlight impinged directly on the heater head tubes of the Stirling Thermal Motors (STM) 4-120 engine. A Sandia-designed felt-metal-wick heat pipe receiver was fitted to the STM 4-120 engine for on-sun testing on Sandia`s Test Bed Solar Concentrator. The heat pipe uses sodium metal as an intermediate two-phase heat transfer fluid. The receiver replaces the directly-illuminated heater head previously tested. The heat pipe receiver provides heat isothermally to the engine, and the heater head tube length is reduced, both resulting in improved engine performance. The receiver also has less thermal losses than the tube receiver. The heat pipe receiver design is based on Sandia`s second-generation felt-wick heat pipe receiver. This paper presents the interface design, and compares the heat pipe/engine test results to those of the directly-illuminated receiver/engine package.

Andraka, C.E.; Rawlinson, K.S.; Moss, T.A.; Adkins, D.R.; Moreno, J.B.; Gallup, D.R.; Cordeiro, P.G. [Sandia National Labs., Albuquerque, NM (United States); Johansson, S. [Stirling Thermal Motors, Inc., Ann Arbor, MI (United States)

1996-07-01T23:59:59.000Z

436

Comparison of Different Upscaling Methods for Predicting Thermal Conductivity of Complex Heterogeneous Materials System: Application on Nuclear Waste Forms  

SciTech Connect

To develop a strategy in thermal conductivity prediction of a complex heterogeneous materials system, loaded nuclear waste forms, the computational efficiency and accuracy of different upscaling methods have been evaluated. The effective thermal conductivity, obtained from microstructure information and local thermal conductivity of different components, is critical in predicting the life and performance of waste form during storage. Several methods, including the Taylor model, Sachs model, self-consistent model, and statistical upscaling method, were developed and implemented. Microstructure based finite element method (FEM) prediction results were used to as benchmark to determine the accuracy of the different upscaling methods. Micrographs from waste forms with varying waste loadings were used in the prediction of thermal conductivity in FEM and homogenization methods. Prediction results demonstrated that in term of efficiency, boundary models (e.g., Taylor model and Sachs model) are stronger than the self-consistent model, statistical upscaling method, and finite element method. However, when balancing computational efficiency and accuracy, statistical upscaling is a useful method in predicting effective thermal conductivity for nuclear waste forms.

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

2013-01-01T23:59:59.000Z

437

Thermal and cost goal analysis for passive solar heating designs  

DOE Green Energy (OSTI)

Economic methodologies developed over the past several years for the design of residential solar systems have been based on life cycle cost (LCC) minimization. Because of uncertainties involving future economic conditions and the varied decision making processes of home designers, builders, and owners, LCC design approaches are not always appropriate. To deal with some of the constraints that enter the design process, and to narrow the number of variables to those that do not depend on future economic conditions, a simplified thermal and cost goal approach for passive designs is presented. Arithmetic and graphical approaches are presented with examples given for each. Goals discussed include simple payback, solar savings fraction, collection area, maximum allowable construction budget, variable cost goals, and Btu savings.

Noll, S.A.; Kirschner, C.

1980-01-01T23:59:59.000Z

438

Preliminary report on the baseline thermal and hydraulic performance tests of a sieve tray direct contact heat exchanger  

DOE Green Energy (OSTI)

A sieve tray direct contact heat exchanger was designed, built and then tested in a binary power cycle at the Raft River geothermal test site. A series of baseline thermal and hydraulic tests were conducted with an isobutane working fluid. The evaluation of these tests is reported. The testing of the DCHX confirmed that the repeated forming and coalescence of the working fluid drops in the sieve tray column produce excellent heat transfer performance. Tray thermal efficiencies were at or above the design value of 70% and the pinch points were well under the design goal of 1/sup 0/F (too small to be measured with installed instrumentation). From a hydraulic standpoint, the column operated at the working fluid velocities from the plate holes corresponding to the predicted condition of maximum total drop surface area (or minimum drop size) when the unit was operating near the flooding limits, or throughputs. This is the recommended working fluid hole velocity for use in designing sieve tray columns. The geothermal flow limits encountered (at flooding) corresponded roughly to the thermal rise velocity of a 1/32-inch drop. This is a drop size commonly used for specifying the terminal velocity (or continuous fluid velocity) in the design of columns for mass transfer applications.

Mines, G.L.

1982-11-01T23:59:59.000Z

439

Field test and assessment of thermal energy storage for residential heating  

SciTech Connect

Thermal energy storage (TES) heating units can be connected to the utility grid to accept electricity only during utility off-peak periods and yet provide round-the-clock comfort heating. Their use by an increasingly larger part of the electric-heat market could provide economic and oil-saving benefits. A field test was carried out over two full heating seasons in Vermont and Maine at 45 TES sites and 30 control sites heated by electric baseboard heaters. The TES users were billed under applicable time-of-day (TOD) rates. All sites were instrumented, and measurements of inside and outside temperatures and electrical energy consumption for heating were made and recorded every 15 min. Analysis of the data has led to the following findings and conclusions: Overall technical performance of the TES units was good under extreme weather conditions. Annualized energy use was the same for the TES and the control households. Proper sizing of the storage systems is much more important for storage heaters than for nonstorage heaters. TES users were satisfied with performance. Electric-heat bills were much lower for TES users. Occupancy effects were large and caused wide variations in energy consumption on days that had the same number of heating degree-days. The individual building heat loss determined experimentally from an analysis of the actual energy consumption per heating degreeday was 30% to 50% smaller than that determined by a walkthrough energy audit.

Hersh, H.

1983-12-01T23:59:59.000Z

440

HEATING THE SOLAR ATMOSPHERE BY THE SELF-ENHANCED THERMAL WAVES CAUSED BY THE DYNAMO PROCESSES  

SciTech Connect

We discuss a possible mechanism for heating the solar atmosphere by the ensemble of thermal waves, generated by the photospheric dynamo and propagating upward with increasing magnitudes. These waves are self-sustained and amplified due to the specific dependence of the efficiency of heat release by Ohmic dissipation on the ratio of the collisional to gyrofrequencies, which in its turn is determined by the temperature profile formed in the wave. In the case of sufficiently strong driving, such a mechanism can increase the plasma temperature by a few times, i.e., it may be responsible for heating the chromosphere and the base of the transition region.

Dumin, Yurii V., E-mail: dumin@yahoo.com, E-mail: dumin@izmiran.ru [Institute of Terrestrial Magnetism, Ionosphere, and Radio Wave Propagation (IZMIRAN), Russian Academy of Sciences, Troitsk, Moscow reg., 142190 (Russian Federation)

2012-05-20T23:59:59.000Z

Note: This page contains sample records for the topic "thermal conductivity heat" from the National Library of EnergyBeta (NLEBeta).
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441

Homogenization and Upscaling for Diffusion, Heat Conduction, and Wave Propagation in Heterogeneous Materials  

SciTech Connect

We present a general homogenization method for diffusion, heat conduction, and wave propagation in a periodic heterogeneous material with piecewise constants. The method is relevant to the frequently encountered upscaling issues for heterogeneous materials. The dispersion relation for each problem is first expressed in the general form where the frequency w (or wavenumber k) is expanded in terms of the wavenumber k (or frequency w). A general homogenization model can be directly obtained with any given dispersion relation. Next step we study the unit cell of the heterogeneous material and derive the exact dispersion relation. The final homogenized equations include both leading order terms (effective properties) and high order contributions that represent the effect of the microscopic heterogeneity on the macroscopic behavior. That effect can be lumped into a single dimensionless heterogeneity parameter, which is bounded between -1/12 less than or equal to less than or equal to 0 and has a universal expression for all three problems. Numerical examples validate the proposed method and demonstrate a significant computational saving.

Zhi-Jie Xu

2012-03-01T23:59:59.000Z

442

A method for the thermal characterization, visualization, and integrity evaluation of conducting material samples or complex structures  

DOE Patents (OSTI)

This invention is useful in thermal imaging of conducting materials, and is particularly useful in measuring thermal conductivity and thermal boundary conditions in composite anisotropic materials, in materials of irregular shape, and in materials for high-temperature applications. It also has utility in visualizing the integrity of complex structures such as a machine, power plant, or chemical plant. The method is for modeling a conducting material sample or structure (system) as an electrical network of resistances, for measuring electric resistance between selected leads attached to the surface of the system, and, using basic circuit theory, for translating measured resistances into temperatures or indications of integrity in corresponding regions of the system. 10 figs.

Ortiz, M.G.

1991-12-31T23:59:59.000Z

443

Interaction of a solar space heating system with the thermal behavior of a building  

DOE Green Energy (OSTI)

The thermal behavior of a building in response to heat input from an active solar space heating system is analyzed to determine the effect of the variable storage tank temperature on the cycling rate, on-time, and off-time of a heating cycle and on the comfort characteristics of room air temperature swing and of offset of the average air temperature from the setpoint (droop). A simple model of a residential building, a fan coil heat-delivery system, and a bimetal thermostat are used to describe the system. A computer simulation of the system behavior has been developed and verified by comparisons with predictions from previous studies. The system model and simulation are then applied to determine the building response to a typical hydronic solar heating system for different solar storage temperatures, outdoor temperatures, and fan coil sizes. The simulations were run only for those cases where there was sufficient energy from storage to meet the building load requirements.

Vilmer, C.; Warren, M.L.; Auslander, D.

1980-12-01T23:59:59.000Z

444

Energy Saving Technology of Thermal Regenerative Compressed Air Dryer by Regenerates Adsorbent with Residual Heat  

Science Conference Proceedings (OSTI)

According to the characteristic of the compressed air dryer located at the same place with the air compressor, for the large capacity thermal regenerative compressed air dryer that the absorbent is regenerated by an electric heater, this thesis puts ... Keywords: Compressed air dryer, Regeneration, Heater, Residual heat, Energy saving

Zhang Mingzhu; Zhou Zhili; Li Hongtao; Zhang Yongbo

2009-10-01T23:59:59.000Z

445

A peridynamic formulation for transient heat conduction in bodies with evolving discontinuities  

Science Conference Proceedings (OSTI)

We introduce a multidimensional peridynamic formulation for transient heat-transfer. The model does not contain spatial derivatives and uses instead an integral over a region around a material point. By construction, the formulation converges to the ... Keywords: Diffusion, Dynamic fracture, Heat flux, Heat transfer, Nonlocal models, Peridynamics

Florin Bobaru; Monchai Duangpanya

2012-04-01T23:59:59.000Z

446

Development of an integrated heat pipe-thermal storage system for a solar receiver  

SciTech Connect

The Organic Rankine Cycle (ORC) Solar Dynamic Power System (SDPS) is one of the candidates for Space Station prime power application. In the low earth orbit of the Space Station approximately 34 minutes of the 94-minute orbital period is spent in eclipse with no solar energy input to the power system. For this period the SDPS will use thermal energy storage (TES) material to provide a constant power output. Sundstrand Corporation is developing a ORC-SDPS candidate for the Space Station that uses toluene as the organic fluid and LiOH as the TES material. An integrated heat-pipe thermal storage receiver system is being developed as part of the ORC-SDPS solar receiver. This system incorporates potassium heat pipe elements to absorb and transfer the solar energy within the receiver cavity. The heat pipes contain the TES canisters within the potassium vapor space with the toluene heater tube used as the condenser region of the heat pipe. During the insolation period of the earth orbit, solar energy is delivered to the heat pipe in the ORC-SDPS receiver cavity. The heat pipe transforms the non-uniform solar flux incident in the heat pipe surface within the receiver cavity to an essentially uniform flux at the potassium vapor condensation interface in the heat pipe. During solar insolation, part of the thermal energy is delivered to the heater tube and the balance is stored in the TES units. During the eclipse period of the orbit, the balance stored in the TES units is transferred by the potassium vapor to the toluene heater tube. 3 refs., 8 figs.

Keddy, E.S.; Sena, J.T.; Merrigan, M.A.; Heidenreich, G.; Johnson, S.

1987-01-01T23:59:59.000Z

447

Radiative component and combined heat transfer in the thermal calculation of finned tube banks  

Science Conference Proceedings (OSTI)

For more exact calculation of combined heat transfer in the case of finned tube banks (e.g., in the convective section of a furnace), the radiative heat transfer cannot be neglected. A new method for relatively simple calculation of total heat flux (convection + radiation + conduction in fins) is fully compatible with that for bare tube banks/bundles developed earlier. It is based on the method of radiative coefficients. However, the resulting value of heat flux must be corrected due to fin thickness and especially due to the fin radiative influence. For this purpose the so-called multiplicator of heat flux was introduced. The applicability of this methods has been demonstrated on a tubular fired heater convective section. A developed computer program based on the method has also been used for an analysis of the influence of selected parameters to show the share of radiation on the total heat flux.

Stehlik, P. [Technical Univ. of Brno (Czech Republic). Dept. of Process Engineering] [Technical Univ. of Brno (Czech Republic). Dept. of Process Engineering

1999-01-01T23:59:59.000Z

448