Thermal Contact Resistance at a Metal Foam-Solid Surface Interface

2011 ◽  
Author(s):  
Ehsan Sadeghi ◽  
Scott Hsieh ◽  
Majid Bahrami
Keyword(s):  
Thermal Conductivity ◽  
Contact Resistance ◽  
Effective Thermal Conductivity ◽  
Contact Area ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Metal Foams ◽  
Real Contact Area ◽  
The Real ◽  
Real Contact

Accurate information on heat transfer and temperature distribution in metal foams is necessary for design and modeling of thermal-hydraulic systems incorporating metal foams. The analysis of this process requires determination of the effective thermal conductivity as well as the thermal contact resistance (TCR) associated with the interface between the metal foams and adjacent surfaces/layers. In the present study, a test bed that allows the separation of effective thermal conductivity and thermal contact resistance in metal foams is described. Measurements are performed in a vacuum under varying compressive loads using ERG Duocel aluminum foam samples with different porosities and pore densities. Also, a graphical method associated with a computer code is developed to demonstrate the distribution of contact spots and estimate the real contact area at the interface. Our results show that the porosity and the effective thermal conductivity remain unchanged with the variation of compression in the range of 0 to 2 MPa; but TCR decreases significantly with pressure due to an increase in the real contact area at the interface. Moreover, the ratio of real to nominal contact area varies between 0 to 0.013, depending upon the compressive force, porosity, and surface characteristics.

Effective Thermal Conductivity of Composites Reinforced with Curvilinearly Anisotropic Inclusions with Kapitza Contact Resistance

2006 ◽  
Vol 306-308 ◽  
pp. 775-780
Author(s):  
Tung Yang Chen
Keyword(s):  
Thermal Conductivity ◽  
Contact Resistance ◽  
Closed Form ◽  
Effective Thermal Conductivity ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Transversely Isotropic ◽  
Closed Form Expression ◽  
Form Expression ◽  
Micromechanical Models

Effective thermal conductivities of composites consisting of curvilinearly anisotropic inclusions with Kapitza thermal contact resistance between the constituents are considered. We show that the effect of these curvilinearly anisotropic inclusions can be exactly simulated by certain equivalent isotropic or transversely isotropic inclusions. Three different micromechanical models are employed to estimate the effective thermal conductivity of the composite. Interestingly, all these methods result in the same simple, closed-form expression.

A Transient Technique to Determine Thermal Conductivity and Thermal Contact Resistance of Porous Materials

2010 ◽  
Author(s):  
Peter De Jaeger ◽  
Christophe T’Joen ◽  
Henk Huisseune ◽  
Michel De Paepe
Keyword(s):  
Thermal Conductivity ◽  
Contact Resistance ◽  
Effective Thermal Conductivity ◽  
Thermal Contact Resistance ◽  
Heat Conduction Problem ◽  
Thermal Contact ◽  
Reference Case ◽  
Transient Technique ◽  
Marquardt Algorithm ◽  
Single Temperature

The application of a transient technique for the measurement of effective thermal conductivity and thermal contact resistance of porous media is discussed. A sensitivity analysis has proven that direct measurement of thermal contact resistance from a single temperature recording is not feasible. It requires the measurement of at least one additional sample with different height. The estimation of effective thermal conductivity is done by solving the inverse heat conduction problem (IHCP). The direct problem is treated analytically by describing the system with a quadrupole formalism in Laplace domain. The inversion procedure was found to be computational expensive. For this reason, the analytical solution of a reference case was obtained and used to validate a finite difference scheme. The indirect problem of the IHCP is solved via the Levenberg-Marquardt algorithm. Preliminary results are shown to demonstrate the method. Future actions consist of calibrating the experimental setup, benchmark with known materials and report uncertainty.

An analytical model of thermal contact resistance based on the Weierstrass—Mandelbrot fractal function

2010 ◽  
Vol 224 (4) ◽  
pp. 959-967 ◽  
Author(s):  
S Jiang ◽  
Y Zheng
Keyword(s):  
Contact Resistance ◽  
Surface Topography ◽  
Contact Area ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Fractal Model ◽  
Design Guidelines ◽  
Real Contact Area ◽  
Fractal Function ◽  
Conduction Theory

A fractal model for analysing the thermal contact resistance (TCR) of rough surfaces is presented; it is based on the classical heat conduction theory and fractal geometry for the surface topography description, elastic—plastic deformation of contacting asperities, and size-dependent constriction resistance. Relations for the TCR in terms of contact load are obtained for heat conductive surfaces with known material properties and surface topography. With the real contact area being approximately 1 per cent of the apparent contact area or less, the microcontact area distribution has a dominant influence on the TCR. Useful design guidelines for heat contacts are extracted from the numerical results. The analytical results agree well with previous experiments.

An FFT Deterministic Simulation of Elastic Rough Surfaces in Three-Dimensional Contact and Model Analysis

2009 ◽  
Author(s):  
Robert L. Jackson ◽  
Itzhak Green
Keyword(s):  
Contact Area ◽  
Thermal Contact Resistance ◽  
Thermal Contact ◽  
Three Dimensional ◽  
Real Contact Area ◽  
Real Contact ◽  
Contact Models ◽  
Surface Profiles ◽  
Rough Surface Contact ◽  
Mathematical Foundations

For practicing engineers in industry it is important to have closed-form, easy to use equations that can be used to predict the real contact area, and relate it to friction, wear, adhesion, and electrical and thermal contact resistance. There are quite a few such models in the literature, but their agreement or their effectiveness has not been determined. This work will use several measured surface profiles to make predictions of contact area and contact force from many elastic contact models and compare them to a deterministic FFT based rough surface contact model. The results show that several of the models show good quantitative and qualitative agreement despite having very different mathematical foundations.

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