Heat exchangers with parallel microchannels,sparse micropillar arrays,and dense micropillar cluster arrays were designed and manufactured to enhance flow boiling heat transfer capabilities in silicon-based microchannels.Flow boiling experiments were conducted with acetone as the working fluid at heat fluxes from 200 to 650 kW·m-2.The results indicated that both sparse and dense micropillar cluster microchannels had superior heat transfer performance compared to parallel microchannels;at a mass flux of 43 kg·m-2·s-1,the average heat transfer coefficients for sparse and dense micropillar cluster microchannels reached 18.6 and 17.8 kW·m-2·K-1,respectively.The sparse micropillar cluster microchannel's performance evaluation criteria(PEC)reached 1.49.The micropillar cluster arrays exhibited three distinct flow patterns as heat flux increased.Visualization investigation showed that the vapor phase in sparse micropillar clusters arrays was prone to flow around the micropillars.It is more inclined to wrap the micro-pillar clusters,which makes the former show stronger two-phase heat transfer performance.
关键词
微通道/微柱簇阵列/相变/气液两相流/强化换热/气泡行为
Key words
microchannels/micropillar cluster arrays/phase change/gas-liquid flow/heat transfer enhancement/bubble behavior
维普
万方数据