Effective Thermal Conductivity and Thermal Contact Conductance of Graphite Fiber Composites

2001 ◽  
Vol 15 (1) ◽  
pp. 18-26 ◽  
Author(s):  
S. R. Mirmira ◽  
M. C. Jackson ◽  
L. S. Fletcher
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Thermal Contact ◽  
Fiber Composites ◽  
Thermal Contact Conductance ◽  
Graphite Fiber ◽  
Contact Conductance

Measurement of the Thermal Contact Conductance and Thermal Conductivity of Anodized Aluminum Coatings

1990 ◽  
Vol 112 (3) ◽  
pp. 579-585 ◽  
Author(s):  
G. P. Peterson ◽  
L. S. Fletcher
Keyword(s):  
Experimental Data ◽  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Coating Thickness ◽  
Thermal Contact ◽  
Thermal Contact Conductance ◽  
Aluminum Surface ◽  
Anodized Aluminum ◽  
Contact Conductance ◽  
Surface Measurements

An experimental investigation was conducted to determine the thermal contact conductance and effective thermal conductivity of anodized coatings. One chemically polished Aluminum 6061-T6 test specimen and seven specimens with anodized coatings varying in thickness from 60.9 μm to 163.8 μm were tested while in contact with a single unanodized aluminum surface. Measurements of the overall joint conductance, composed of the thermal contact conductance between the anodized coating and the bare aluminum surface and the bulk conductance of the coating material, indicated that the overall joint conductance decreased with increasing thickness of the anodized coating and increased with increasing interfacial load. Using the experimental data, a dimensionless expression was developed that related the overall joint conductance to the coating thickness, the surface roughness, the interfacial pressure, and the properties of the aluminum substrate. By subtracting the thermal contact conductance from the measured overall joint conductance, estimations of the effective thermal conductivity of the anodized coating as a function of pressure were obtained for each of the seven anodized specimens. At an extrapolated pressure of zero, the effective thermal conductivity was found to be approximately 0.02 W/m-K. In addition to this extrapolated value, a single expression for predicting the effective thermal conductivity as a function of both the interface pressure and the anodized coating thickness was developed and shown to be within ±5 percent of the experimental data over a pressure range of 0 to 14 MPa.

Thermal Contact Conductance of a Bone-Dry Paper Handsheet/Metal Interface

1992 ◽  
Vol 114 (2) ◽  
pp. 326-330 ◽  
Author(s):  
J. Seyed-Yagoobi ◽  
K. H. Ng ◽  
L. S. Fletcher
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Water Retention ◽  
Thermal Contact ◽  
Thermal Contact Conductance ◽  
Metal Interface ◽  
Contact Conductance ◽  
Interface Contact ◽  
Sheet Density

An apparatus was constructed for determination of the thermal contact conductance for a paper handsheet/metal interface and for measurement of the effective thermal conductivity of handsheet samples. Bone-dry Bleached Southern Mixed Kraft hand-sheets with a water retention value of 1.832 were used to study the effect of pressure on thermal contact conductance and to measure the effective thermal conductivity of samples at various sheet density levels. A regression model describing the interface thermal contact conductance as a function of pressure and basis weight was derived. The contact conductance increases with increasing pressure or with decreasing basis weight. At a pressure of 2.3 kPa, the value of the interface contact conductance for the bone-dry samples considered ranges from approximately 97 W/m2K for a sheet of 348.7 g/m2 basis weight to 200 W/m2K for a sheet of 68.0 g/m2 basis weight. For pressures near 300 kPa, these values increase to 146 and 452 W/m2K, respectively. The effective thermal conductivity of the handsheet samples was derived from measured values of overall joint conductance and interface contact conductance. The results indicate that the thermal conductivity of the bone-dry samples increases with increasing sheet density, ranging from 0.14 W/mK to 0.70 W/mK for sheet densities of 90 kg/m3 to 500 kg/m3, respectively, for the samples considered.

Influence of Contact Mechanics in the Prediction of the Effective Thermal Conductivity of Spheroid Packed Beds

2003 ◽  
Author(s):  
G. Buonanno ◽  
A. Carotenuto ◽  
G. Giovinco ◽  
L. Vanoli
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Statistical Approach ◽  
Thermal Contact ◽  
Peak Height ◽  
Thermal Contact Conductance ◽  
Curvature Radius ◽  
Packed Beds ◽  
Wide Range ◽  
Thermal Phenomena

Thermal contact conductance is an important parameter in a wide range of thermal phenomena, and consequently a large number of experimental, numerical and statistical investigations have been carried out in literature. In the present paper an analysis of thermal contact resistance is carried out to predict heat transfer between spherical rough surfaces in contact, by means of a statistical approach. The micro-geometry of the surface is described through a probabilistic model based on the peak height variability and invariant asperity curvature radius. The numerical model has been applied to evaluate the effective thermal conductivity of packed beds of steel spheroids and validated through the comparison with the experimental data obtained by means of an apparatus designed and build up for this purpose.

Anisotropic Heat Conduction Effects in Proton-Exchange Membrane Fuel Cells

2006 ◽  
Vol 129 (9) ◽  
pp. 1109-1118 ◽  
Author(s):  
Chaitanya J. Bapat ◽  
Stefan T. Thynell
Keyword(s):  
Thermal Conductivity ◽  
Temperature Distribution ◽  
Thermal Contact ◽  
Current Collector ◽  
Gas Diffusion ◽  
Thermal Contact Conductance ◽  
Contact Conductance ◽  
Gas Diffusion Layers ◽  
Diffusion Layers ◽  
Anisotropic Thermal Conductivity

The focus of this work is to study the effects of anisotropic thermal conductivity and thermal contact conductance on the overall temperature distribution inside a fuel cell. The gas-diffusion layers and membrane are expected to possess an anisotropic thermal conductivity, whereas a contact resistance is present between the current collectors and gas-diffusion layers. A two-dimensional single phase model is used to capture transport phenomena inside the cell. From the use of this model, it is predicted that the maximum temperatures inside the cell can be appreciably higher than the operating temperature of the cell. A high value of the in-plane thermal conductivity for the gas-diffusion layers was seen to be essential for achieving smaller temperature gradients. However, the maximum improvement in the heat transfer characteristics of the fuel cell brought about by increasing the in-plane thermal conductivity is limited by the presence of a finite thermal contact conductance at the diffusion layer/current collector interface. This was determined to be even more important for thin gas-diffusion layers. Anisotropic thermal conductivity of the membrane, however, did not have a significant impact on the temperature distribution. The thermal contact conductance at the diffusion layer/current collector interface strongly affected the temperature distribution inside the cell.

Sodium Silicate Based Thermal Interface Material for High Thermal Contact Conductance

1999 ◽  
Vol 122 (2) ◽  
pp. 128-131 ◽  
Author(s):  
Yunsheng Xu ◽  
Xiangcheng Luo ◽  
D. D. L. Chung
Keyword(s):  
Thermal Conductivity ◽  
Boron Nitride ◽  
Sodium Silicate ◽  
Hexagonal Boron Nitride ◽  
Thermal Contact ◽  
Mineral Oil ◽  
Thermal Interface Material ◽  
Thermal Contact Conductance ◽  
Thermal Interface ◽  
Contact Conductance

Sodium silicate based thermal interface pastes give higher thermal contact conductance across conductor surfaces than polymer based pastes and oils, due to their higher fluidity and the consequent greater conformability. Addition of hexagonal boron nitride particles up to 16.0 vol. percent further increases the conductance of sodium silicate, due to the higher thermal conductivity of BN. However, addition beyond 16.0 vol. percent BN causes the conductance to decrease, due to the decrease in fluidity. At 16.0 vol. percent BN, the conductance is up to 63 percent higher than those given by silicone based pastes and is almost as high as that given by solder. Water is almost as effective as sodium silicate without filler, but the thermal contact conductance decreases with time due to the evaporation of water. Mineral oil and silicone without filler are much less effective than water or sodium silicate without filler. [S1043-7398(00)00402-3]

Influence of Contact Pressure on the Thermal Contact Conductance of Layered AA3003 Aluminium

2020 ◽  
Vol 15 ◽  
Keyword(s):  
Thermal Conductivity ◽  
Contact Pressure ◽  
Thermal Contact ◽  
Thermal Conductance ◽  
Thermal Contact Conductance ◽  
Contact Conductance ◽  
Interface Thermal Resistance ◽  
Measurement Results ◽  
Semi Empirical ◽  
The Relationship

For the optimization of the annealing process of aluminium coils, simulation of the process is often performed. To simulate the process with higher accuracy, reliable input parameters are required and the thermal conductivity (thermal contact conductance) is one of them. In the present study, the thermal conductivity and thermal contact conductance of AA3003 alloy sheets were measured by a steady state comparative longitudinal heat flow method at different contact pressure. To evaluate the thermal conductance at the interface, thermal resistance network model' was applied. In addition, the surface roughness of the sheets was also investigated. Based on the measurement results, the semi-empirical equation for the relationship between thermal contact conductance and contact pressure was obtained

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