An experimental and numerical study of finned metal foam heat sinks under impinging air jet cooling

This paper presents a combined experimental and numerical study on finned metal foam (FMF) and metal foam (MF) heat sinks under impinging air jet cooling. Experiments were conducted on aluminum foams of 96.3% porosity and 8 PPI (pores per inch) with four 2 mm-thickness plate fins. Different foam heights were tested at varying Reynolds numbers. Experimental results show that under a given flow rate condition, as the foam height increases, the heat transfer of MF heat sinks decreases monotonously whilst that of FMF heat sinks first increases and then slightly decreases. Under a given pumping power condition, the heat transfer of MF heat sinks is insensitive to the foam height whilst that of FMF heat sinks increases as the foam height increases. Under either a given flow rate or a given pumping power condition, the heat transfer of FMF heat sinks can be 1.5-2.8 times that of the MF heat sinks having the same height. A numerical model was also developed to simulate the conjugated heat transfer between plate-fins and metal foams in FMF heat sinks. The influence of the bonding material between metal foams and plate-fins as well as the inlet thermal boundary condition were discussed in detail using the numerical model. Comparisons of experimental and numerical results reveal that using the laminar Darcy's extended model can predict fairly both the heat transfer and pressure drop of MF and FMF heat sinks under high Reynolds numbers if the foam properties are given correctly.