微通道热沉内液氮的流动沸腾换热实验

通过实验研究了质量流量在62.6~598.6kg/(m2·s)下不锈钢材质的平行微通道热沉内液氮流动沸腾的传热特性,并将实验所测得局部换热系数与经验关联式计算所得结果进行比较.结果表明:在核态沸腾阶段,随着干度增大,热沉的局部换热系数增加并逐渐达到一个峰值;当干度继续增大时换热系数逐渐减小;热沉的局部换热特性受其流型和低温流体工质特殊性的影响,在干度较低的条件下,其实验结果与模型预测结果的变化趋势一致,但预测值大于实验值.

Experimental Investigation of Heat Transfer Characteristics of Flow Boiling of Liquid Nitrogen in Micro Channels Heat Sink

The flow boiling of liquid nitrogen in a micro-channel heat sink was experimentally studied for mass fluxes ranging from 62.6 to 598 kg/(m2·s). The heat sink was made of stainless steel. The experimental results showed that the heat transfer coefficient significantly increased with heat flux at low vapor quality where heat transfer was dominated by nucleate boiling. The heat transfer coefficient first increased with heat flux and then decreased with the increase in vapor quality after the heat transfer coefficient reached the peak value, which was due to flow pattern transition and the local dry-out. The experimental data was compared with the empirical correlations. Both results showed similar trend, but the calculated results were larger than the experimental ones.