High heat flux dissipation of membrane-venting heat sink with thin film boiling

Microchannel flow boiling exhibits outstanding heat transfer capabilities, rendering it a promising technology for cooling high heat flux devices. Nonetheless, rapid vapor generation in the channels increases pressure drop and leads to local dryness, restricting the performance of microchannel heat sinks. In this study, we designed a membrane-venting heat sink that has a hydrophobic porous membrane above a thin liquid film for venting vapor. The phase change of this heat sink comprises not only thin film flow boiling in the horizontal direction but also thin film boiling and thin film evaporation in the vertical direction, thereby mitigating the detrimental effects of flow boiling. Experiments indicate that utilizing a membrane with 1.0 mu m pore size for venting can enable the effective heat flux of the heat sink to achieve 287.8 W/cm2, with a transmembrane heat flux of 152.7 W/cm2. Furthermore, the surging trend of pressure drop with heat flux was significantly slowed down, and the maximum effective heat flux increased by 553 % compared to the configuration without vent. This study demonstrates that adding and enhancing the vertical heat and mass transfer channels via hydrophobic porous membranes is a potent method for considerably improving flow boiling.