丙烯环路热管补偿器的可视化实验研究

通过采用石英补偿器和高速摄像机实现了对丙烯环路热管补偿器的可视化实验研究，重点研究了补偿器内工质的状态随充装量和传热量的变化及充装量对环路热管传热性能的影响。研究发现，容积为51.4 mL的环路热管最佳充装量约为19.7 g。充装量小于最佳充装量的各工况下，能观察到对应补偿器内工质液面高度低于引流管，蒸发器和补偿器之间相变换热强烈，引流管外壁面明显有工质的冷凝及流动，且工质冷凝和流动的速度随着传热量的增加而加快；随着充装量增加，环路热管传热热阻减小，280 K工作温度以下的传热量增大。最佳充装量对应的补偿器内液面高度浸没引流管而接近蒸发器核心通道顶端，得到280 K以下最大传热量为40 W，对应的最优传热热阻为2 K/W。充装量大于最佳充装量的工况下，补偿器内液面高度超过蒸发器核心顶端，随着充装量增加，环路热管传热热阻增大，280 K以下的传热量减小。补偿器和蒸发器核心通道内的工质分布能影响蒸发器向补偿器的漏热量，这是充装量影响环路热管性能的重要原因。 

Visualization experimental study of compensation chamber of a propylene loop heat pipe

By the employment of quartz compensation chamber and high-speed camera, the visualization experimental study on the compensation chamber of a propylene loop heat pipe was implemented, which mainly focused on the variation of state of working fluid in the compensation chamber with the effect of the working fluid inventory and heat transfer capacity, and the effect of working fluid inventory on the heat transfer performance of the loop heat pipe. The results indicate that the optimal working fluid inventory for the loop heat pipe with volume of 51.4 mL is about 19.7 g. The liquid levels inside the compensation chamber are lower than the bayonet when the fluid inventory is less than the optimal one, intense two-phase heat exchange between the evaporator and the compensation chamber is confirmed by the observation of obvious condensation and flow of the liquid on the outer surface of the bayonet, and the condensation rate and flow velocity increase with the rise of heat transfer capacity; the heat transfer thermal resistance of the loop heat pipe decreases and the heat transfer capacity below 280 K increases with the rise of the fluid inventory. With an optimal fluid inventory, the liquid level inside the compensation chamber immerses the bayonet and is close to the top of the evaporator core, and thus the best performance is obtained: a maximum power of 40 W that can be transferred below 280 K and a corresponding thermal resistance of 2 K/W. Liquid levels inside the compensation chamber are higher than the top of the evaporator core when the fluid inventory is more than the optimal one. The heat transfer thermal resistance increases and the heat transfer capacity below 280 K decreases with the rise of the fluid inventory. The liquid distribution inside the compensation chamber and evaporator core has considerable effect on the heat leak between the evaporator and the compensation chamber, which is a significant factor for the influence of working fluid inventory on the performance of loop heat pipe.