High Heat Flux Two-Phase Cooling in Silicon Multimicrochannels

This paper presents performances of two-phase cooling of a chip at very high heat flux with refrigerant R236fa in a silicon multimicrochannel heat sink. This heat sink was composed of 134 parallel channels, 67 mum wide, 680 mum high, and 20 mm long, with 92- mum -thick fins separating the channels. The base heat flux was varied from 3 to 255 W/cm² , the volume flow rate from 0.18 to 0.67 I/min, and the exit vapor quality from 0 to 80%. The working pressure and saturation temperature were set at 273 kPa and 25 degC, respectively. The present database includes 1040 local heat transfer coefficients. The base temperature of the chip could be maintained below 52 degC while dissipating 255 W/cm² with 10 degC of inlet subcooling and 90 kPa of pressure drop. A comparison of the respective performances with an extrapolation of the present results shows that two-phase cooling should be able to cool the chip 13 K lower than liquid cooling for the same pumping power at a base heat flux of 350 W/cm².