Experiments were conducted to study the effect of the size of micro-pin fin on boiling heat transfer from a silicon chip immersed in a pool of degassed or gas-dissolved FC-72. Four kinds of micro-pin fins with dimensions of 10 × 60, 20 × 60, 30 × 60, and 50 × 60 μm2 (thickness × height) were fabricated on the surface of a square silicon chip with dimensions of 10 × 10 × 0.5 mm3 using the dry etching technique. Experiments were conducted at liquid subcooling of 0, 3, 25, and 45 K under atmospheric conditions. The results were compared with those for a smooth chip and previously developed enhanced surfaces. The micro-pin-finned chips showed a considerable heat transfer enhancement over the smooth chip in the nucleate boiling region. The boiling curve showed a steep increase in heat flux with increasing wall superheat. For the micro-pin-finned chips, the critical heat flux was 1.9-2.3 times as large as for the smooth chip, and the wall temperature at the critical heat flux point was lower than the upper limit for the reliable operation of large-scale integration (LSI) chips (=85°C). While the wall superheat at boiling incipience was strongly dependent on the dissolved gas content, it was little affected by the liquid subcooling.
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