液氮温区平板蒸发器环路热管实验研究

深低温环路热管是一种高效的深低温两相传热器件，未来可广泛应用于红外探测等空间项目的低温热控系统。为有效减小热管与热负荷间的接触热阻及热管的背向漏热，采用氧化锆作为毛细芯材料，研发了氮工质平板蒸发器环路热管，重点研究了热管的自启动特性、传热性能以及在间歇性热负荷下的运行情况。结果表明:在无辅助情况下，液氮温区平板蒸发器环路热管自启动性能良好，可依靠工质扩散从室温迅速降温至液氮温区。环路热管能够在70~100 K温区稳定运行，热阻随运行温度和热负荷的上升而减小，最大传热功率为15 W，最小热阻为0.8 K/W。在蒸发器间歇性加热的情况下，环路热管可以保持温度稳定，热响应迅速，无需二次降温。液氮温区平板蒸发器环路热管有效满足了空间低温光学系统的热控制系统的热传输需求。 

Experimental study on a liquid nitrogen temperature region loop heat pipe with flat evaporator

The cryogenic loop heat pipe is an efficient deep-hypothermic two-phase heat transfer device, which will be widely applied to cryogenic thermal control system for space projects such as infrared detection in the future. Zirconia is used to develop nitrogenous flat evaporator loop heat pipe for capillary wicking materials, effectively reducing the contact thermal resistance between the heat pipe and the heat load and the back leakage heat of the heat pipe. The experiment focuses on studying the non-assisted start-up characteristics, heat transfer performance and operation under intermittent thermal load of the heat pipe. The conclusion was drawn as follows:the flat evaporator loop heat pipe at liquid nitrogen temperature is in a good condition of self-start performance without assistance, which can be rapidly cooled down from room temperature to liquid nitrogen temperature by the diffusion of working fluids. The loop heat pipe can stably run from the liquid nitrogen temperature of 70 K to 100 K, and the thermal resistance will decrease with the increase of operating temperature and heat load at the maximum heat transfer power of 15 W and the minimum thermal resistance of 0.5 K/W. The loop heat pipe can keep the temperature stable and thermal response fast under the condition of intermittent heating of evaporator without secondary cooling. The flat evaporator loop heat pipe at liquid nitrogen temperature region effectively meets the requirements for the heat transfer of the thermal control system of the space cryogenic optical system.