并行蒸发器两相冷却系统支路散热不平衡性的实验研究

Experimental Investigation on Imbalance Heat Load of the Two-phase Dual-Evaporator Cooling System

对并行蒸发器机械泵驱动两相流冷却系统各个支路散热量不平衡条件下散热特性进行实验研究,结果表明并行蒸发段各支路的流量分配同管路的阻力有关,当上下两侧蒸发器的热量不平衡时,质量流量的分配始终是一个动态的变化过程,其中,热负荷较大的一侧,阻力不断增加,流量逐渐减小,而热负荷较小的一侧流量在不断变大,并且热量差越大,流量差变化越快;当减小并行支路的热量差有利于蒸发段的散热平衡,热量差越小,系统散热稳定性越强。同毛细泵驱动的两相冷却系统相比,机械泵驱动的两相流冷却系统的散热性好,等温性高,热不平衡处理能力强,并行支路热负荷之差可以达到100多倍,并且能够保持较长的稳定运行。

A brief review of the two-phase cooling loop driven by mechanical pump is presented, and a proposed experimental system with dual-Evaporator by using CO2 as the working fluid is described. In order to apply this technology for the thermal control systems, tests have been performed to clearly comprehend its performance under cyclic temperature changing. Special attention has been paid to the heat rejection characteristics under unbalance heat load on the dual-Evaporator. From the experiments, it demonstrates that when heat load unbalance happens , the mass flow distribution between two branch has changed, the higher heat load is, the smaller mass flow is got- ten. At last the mass flow would gasify completely and temperature at the outlet of a higher heat load branch would enhance. Meanwhile, decreasing heat load difference is benefit for the mass flow equalization and is an effective means for the evaporative stability. In a word, the two-phase Mechanical Pumped Cooling System with dual-Evaporator has more advantages than capillary pump cooling loop not only on the heat rejection capacity and isothermal characteristic but also on dealing with unbalance heat load.