Heat transfer performance of uni-directional porous heat sink for cooling of next generation on-vehicle inverter

This study evaluates boiling and evaporative heat transfer performance of a heat sink called EVAPORON-4 utilizing uni-directional porous media in order to remove high heat generation of 300-500 W/cm
²
from a chip of the next generation SiC-/GaN-based on-vehicle inverter. The unidirectional porous heat sink has three functions such as direct supply of cooling liquid to a heat transfer surface, promotion of evaporation, and passive vapor discharge. The porous medium is made of oxygen free copper and the porosity is 19.6 %. The small pore holes of 0.5 mm in diameter work for the liquid supply and the large holes of 2.6 mm for the vapor discharge. In order to discharge the vapor through the vapor discharge pore holes, the porous heat sink is set onto a grooved heat transfer surface. As a result, the porous heat sink achieves high cooling performance of approximately 850 W/cm
²
at the pumping power of 2.6 W in case of the liquid subcooling of 40 K and the flow rate of 2.0 L/min (102 kg/m
²
/s).