Thermal Performance of Liquid-Cooled Metal Foams Attached Using Different Thermal Interface Materials

This study experimentally and computationally investigates the convection heat transfer performance of metal foams (MFs) having the same pores per inch (PPI) but different porosities attached to a uniformly heated surface using three different thermal interface materials (TIMs). Of the three TIMs considered, flexible graphite showed the best heat transfer performance by around 10%-25% compared to the reference case, where no TIM was used, due to its high in-plane thermal conductivity. In contrast, thermal epoxy was the worst, with a decrease in heat transfer by around 10%-30%, relative to the reference case. A comparable performance to the reference case was exhibited by the thermal gap pad. The MF hydraulic modeling parameters were extracted from the pressure drop data, and pore and filament diameters were obtained from micro-CT ( mu CT) scans and used in the numerical simulations. Thermal contact resistances (TCRs) are assessed from the numerical simulations. The results showed that total TCR tends to increase with increasing filament diameter and decreasing porosity. Moreover, the steady-state thermal analyses showed that the flexible graphite effectively spreads the heat in the TIM and reduces the overall TCR. Detailed temperature contours on the heated surface of the thermal gap pad and flexible graphite TIMs used with different porosity MFs are presented to support these findings.