Simulations of Metal Foam Cooling of High-Power Electronics Using the Equivalent Thermal Conductivity

Abstract

A one-dimensional heat transfer model for open-cell metal foam is presented. The model includes both the conduction and the convection in the ligaments and in the pores of the foam. It uses the typical foam parameters provided by the manufacturers. Three aluminum foams having different relative surface areas, relative densities, ligament diameters, and number of pores per inch are analyzed and an effective thermal conductivity is determined. The heat transfer increases with the number of pores per inch. The resulting improvement in heat transfer can be as high as 57 percent over solid aluminum. The model is general enough such that it can handle other types of foam and geometries. For simulations using packages for thermal management, the foam can be modeled as a solid having an equivalent conductivity with an effective convection heat transfer on its outer surfaces. This eliminates the need to model the microscopic flow and heat transfer in and around the pores. It also allows quick feasibility studies and comparisons of different arrangements using aluminum foams for thermal management systems of high-power electronics. A few such simulations are presented in this work. The simulations show a big promise for using the foam in place of the traditional heat sinks for cooling high-power electronics: they reduce the cooling system’s weight substantially and reduce the maximum temperature significantly.