Comparison of Effective Thermal Conductivity and Contact Conductance of Fibrous Composites

1999 ◽  
Vol 13 (2) ◽  
pp. 272-276 ◽  
Author(s):  
S. R. Mirmira ◽  
L. S. Fletcher
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Fibrous Composites ◽  
Contact Conductance

Thermal Transport in Nanotube Composites for Large-Area Macroelectronics

2005 ◽  
Author(s):  
Satish Kumar ◽  
Muhammad A. Alam ◽  
Jayathi Y. Murthy
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Thermal Transport ◽  
Channel Length ◽  
Tube Length ◽  
Finite Volume Scheme ◽  
Large Area ◽  
Contact Conductance ◽  
Channel Lengths ◽  
Contact Parameters

Thermal transport in a new class of nanocomposites composed of isotropic 2D ensembles of nanotubes or nanowires in a substrate is considered for use as the channel region of thin film transistors. The random ensemble is generated numerically and simulated using a finite volume scheme. The effective thermal conductivity of a nanotube network embedded in a thin substrate is computed. Percolating conduction in the composite is studied as a function of wire/tube densities and channel lengths. The conductance exponents are validated against available experimental data for long channels devices. The effect of tube-tube contact conductance, tube-substrate contact conductance and substrate-tube conductivity ratio is analyzed for various channel lengths. It is found that beyond a certain limiting value, contact parameters do not result in any significant change in the effective thermal conductivity of the composite. It is also observed that the effective thermal conductivity of the composite saturates beyond a limiting channel-length/tube length ratio for the range of contact parameters under consideration.

Nonsteady Effective Thermal Conductivity of Dense Fibrous Composites with Graded Interface

2010 ◽  
Vol 24 (2) ◽  
pp. 316-324 ◽  
Author(s):  
Xue-Qian Fang ◽  
Xiao-Hua Wang ◽  
Chao Hu ◽  
Wen-Hu Huang
Keyword(s):  
Thermal Conductivity ◽  
Effective Thermal Conductivity ◽  
Fibrous Composites

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.

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