An approach for simulating metal foam cooling of high-power electronics

A one-dimensional heat transfer model for a thin piece of open-cell metal foam is presented. The model includes both the conduction in the ligaments, and the convection due to airflow in and around the pores of the foam. It uses the typical foam parameters provided by the manufacturers. Three aluminum foam samples having different relative surface areas, relative densities, ligament diameters, and number of pores per inch are analyzed. The heat transfer is concentrated in a region close to the heated base. Based on this one-dimensional model, a simple technique is developed for simulating the heat transfer inside the foam in 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 only. This eliminates the need to model the complex microscopic flow and heat transfer in and around the pores. It also allows quick feasibility studies, comparisons and trade-off analysis of different cooling arrangements. Three aluminum foam samples were tested in the lab and were simulated in ANSYS. The agreement between ANSYS simulation and the experiment was very good.