Comparative study of temperature and pressure instabilities during flow boiling in straight- and 10° oblique-finned microchannels

摘要

Flow boiling experiments are conducted in straight- and oblique-finned microchannels with similar channel dimensions and operating conditions using the FC-72 dielectric fluid. Both the test pieces are made from a copper block with a footprint area of 25 mm × 25 mm and 40 parallel microchannels. The oblique cuts are created at a nominal oblique angle of 10° with a nominal width which is half of that of the parallel microchannels. Two mass fluxes at 175 kg/m~2 s and 370 kg/m~2 s, with heat fluxes from 14 W/cm~2 to 42 W/cm~2 are tested. Wall temperature and pressure fluctuations during the flow boiling process are presented in this article. It is found that the oblique-finned configuration considerably mitigates temperature and pressure instabilities at various operating conditions, apart from augmentation in heat transfer performance. The increased flow stability is attributed to the ability of the oblique fins in reducing flow reversal. These results show that the oblique-finned microchannels present an interesting thermal management technique for stabilised two-phase cooling.