Pool boiling heat transfer of dual-scale porous microchannel for high-power electronics cooling

Surface modifications for boiling enhancement are urgently required for cooling high-power electronics. In the study, a dual-scale porous microchannel fabricated by plough-extrusion, wire electrical discharge machining, and ultrasonic machining is developed to meet the pressing needs. Boiling performance and bubble behaviors on the proposed microchannel are investigated, and the effect of the liquid subcooling on heat transfer is analyzed. The proposed microchannel is capable of dissipating heat flux of 2319.7 kW/m² without reaching CHF, and exhibits a high HTC of 243.3 kW/(m²K) at saturation boiling with water. The complex microchannels with interconnected holes, reentrant cavities and micro-nanopores enhance the heat transfer by enlarging surface area, increasing nucleate sites, strengthening capillary wicking, and inducing macroconvection. The increased subcooling degree of pool liquid inhibits the nucleate boiling at low heat flux, but enhances the heat transfer at high heat flux which is the main region of interest. DPM with all the merits is highly promising for cooling high-power electronics.