scholarly journals Estimation of the effective thermal conductivity of rocks in situ by cuttings. Part 2. Heat conduction analysis of cuttings-water mixture beds and case studies for a test well at Fushime geothermal field, Kyushu, Japan.

1989 ◽  
Vol 54 (6) ◽  
pp. 474-483 ◽  
Author(s):  
Hiroshi KIYOHASHI ◽  
Toshiyuki WATANABE ◽  
Munesuke KYO ◽  
Yuzaburo YOSHIMURA ◽  
Shozo TANAKA
Keyword(s):  
Thermal Conductivity ◽  
Heat Conduction ◽  
Effective Thermal Conductivity ◽  
Case Studies ◽  
Geothermal Field ◽  
Water Mixture

Modeling Heat Conduction Across Thermal Interface Materials With Micro-Particles

2008 ◽  
Author(s):  
C. Channy Wong
Keyword(s):  
Thermal Conductivity ◽  
Heat Conduction ◽  
Composite Materials ◽  
Effective Thermal Conductivity ◽  
Thermal Interface Materials ◽  
Conduction Path ◽  
Micro Particles ◽  
Mechanical And Electrical Properties ◽  
Interface Materials ◽  
Composite Polymeric Material

Different types of fillers with high electrical and thermal conductivities, e.g. graphite and alumina, have been added to adhesive polymers to create composite materials with improved mechanical and electrical properties. Previous modeling efforts have found that it is relatively difficult to predict the effective thermal conductivity of a composite polymeric material when incorporated with large volume content of fillers. We have performed comprehensive computational analysis that models the thermal contacts between fillers. This unique setup can capture the critical heat conduction path to obtain the effective thermal conductivity of the composite materials. Results of these predictions and its comparison with experimental data will be presented in this paper.

Effect of radial heat conduction on effective thermal conductivity of carbon nanotube bundles

2018 ◽  
Vol 61 (12) ◽  
pp. 1959-1966 ◽  
Author(s):  
JianLi Wang ◽  
YaMei Song ◽  
YuFeng Zhang ◽  
YuHan Hu ◽  
Hang Yin ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Heat Conduction ◽  
Carbon Nanotube ◽  
Effective Thermal Conductivity ◽  
Nanotube Bundles ◽  
Radial Heat

Nanofluids Suspensions: Possible Explanations for the Apparent Enhanced Effective Thermal Conductivity

2005 ◽  
Author(s):  
Peter Vadasz
Keyword(s):  
Heat Transfer ◽  
Thermal Conductivity ◽  
Heat Conduction ◽  
Effective Thermal Conductivity ◽  
Heterogeneous Medium ◽  
Alternative Possibilities ◽  
Dual Phase ◽  
Transfer Enhancement ◽  
Scale Level ◽  
Macro Scale

The spectacular heat transfer enhancement revealed experimentally in naofluids suspensions is being investigated theoretically at the macro-scale level aiming at explaining the possible mechanisms that lead to such impressive experimental results. In particular, the possibility that Dual-Phase-Lagging heat conduction in the heterogeneous medium (nanofluid suspension) could have been the source of the excessively improved effective thermal conductivity of the suspension is shown to provide a viable explanation. The investigation of alternative possibilities is needed however prior to reaching an ultimate conclusion.

In Situ Characterization of Coal Ash Thermal Conductivity Under Oxidizing and Reducing Conditions

2011 ◽  
Author(s):  
D. Cundick ◽  
D. Maynes ◽  
T. Moore ◽  
D. R. Tree ◽  
M. R. Jones ◽  
...  
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Flow Reactor ◽  
Coal Ash ◽  
In Situ Measurements ◽  
Powder River Basin ◽  
Reducing Conditions ◽  
Bituminous Coals ◽  
Thermal Conductivities

This work presents in situ measurements of the effective thermal conductivity in particulate coal ash deposits under both reducing and oxidizing environments. Laboratory experiments generated deposits on an instrumented deposition probe of loosely-bound particulate ash from three coals generated in a down-fired flow reactor with optical access. An approach is presented for making in situ measurements of the temperature difference across the ash deposits, the thickness of the deposits, and the total heat transfer rate through the ash deposits. Using this approach, the effective thermal conductivity was determined for coal ash deposits formed under oxidizing and reducing conditions. Three coals were tested under oxidizing conditions: two bituminous coals derived from the Illinois #6 basin and a subbituminous Powder River Basin coal. The subbituminous coal exhibited the lowest range of effective thermal conductivities (0.05–0.18 W/m· K) while the Illinois #6 coals showed higher effective thermal conductivities (0.2–0.5 W/m· K). One of the bituminous coals and the subbituminous coal were also tested under reducing conditions. A comparison of the ash deposits from these two coals showed no discernible difference in the effective thermal conductivity based on stoichiometry. All experiments indicated an increase in effective thermal conductivity with deposit thickness, probably associated with deposit sintering.

scholarly journals Impact of water vapor diffusion and latent heat on the effective thermal conductivity of snow

2020 ◽  
Author(s):  
Kévin Fourteau ◽  
Florent Domine ◽  
Pascal Hagenmuller
Keyword(s):  
Thermal Conductivity ◽  
Diffusion Coefficient ◽  
Heat Conduction ◽  
Water Vapor ◽  
Effective Thermal Conductivity ◽  
Latent Heat ◽  
Effective Diffusion Coefficient ◽  
Effective Diffusion ◽  
Water Vapor Transport ◽  
Fast Kinetics

Abstract. Heat transport in snowpacks is generally thought to occur through two independent processes: heat conduction and latent heat transport carried by water vapor. This paper investigates the coupling between both these processes in snow, with an emphasis on the impacts of the kinetics of the sublimation and deposition of water vapor onto ice. In the case where kinetics is fast, latent heat exchanges at ice surfaces modify their temperature, and therefore the thermal gradient within ice crystals and the heat conduction through the entire microstructure. Furthermore, in this case, the effective thermal conductivity of snow can be expressed by a purely conductive term complemented by a term directly proportional to the effective diffusion coefficient of water vapor in snow, which illustrates the inextricable coupling between heat conduction and water vapor transport. Numerical simulations on measured three-dimensional snow microstructures reveal that the effective thermal conductivity of snow can be significantly larger, up to about 50 % for low-density snow, than if water vapor transport is neglected. Comparison of our numerical simulations with literature data suggests that the fast kinetics hypothesis could be a reasonable assumption to model snow physical properties. Lastly, we demonstrate that under the fast kinetics hypothesis the effective diffusion coefficient of water vapor is related to the effective thermal conductivity by a simple linear relationship. Under such condition, the effective diffusion coefficient of water vapor is expected to lie in the narrow 100 % to about 80 % range of the value of the diffusion coefficient of water vapor in air for most seasonal snows. This may greatly facilitate the parameterization of water vapor diffusion of snow in models.

Sign in / Sign up

Export Citation Format

Share Document