BOILING/EVAPORATION HEAT TRANSFER AUGMENTATION USING SUBCHANNELS-INSERTED METAL POROUS MEDIA

摘要

Two-phase flow loop system using a metal porous heat sink is proposed as a cooling system of the future power electronic devices with a heat load exceeding 300W/cm~2. In this paper, as the first step, the heat transfer performance of the porous heat sink is evaluated under high heat flux conditions and the applicability and some engineering issues are discussed. The porous medium, which is fabricated by sintering copper particles, has a functional structure with several sub-channels inside it to enhance phase-change as well as discharge of generated vapor outside the porous medium. This porous heat sink is attached onto a heating chip and removes the heat by evaporating cooling liquid passing through the porous medium against the heat flow. Experiments using 30 kW of heating system show that the heat transfer performance of a copper-particles-sintered porous medium with the sub-channels exceeds 800W/cm~2 in both high and low subcooling cases and achieves 300W/cm~2 at a wall temperature of 150 °C (T_(in)=70 °C) and 130 °C (T_(in)=70 °C). These results prove that this porous heat sink is applicable enough for cooling 300 W/cm~2 class of power electronic devices.