Abstract: Vapor compression heat pump has a good prospect of application in high temperature environments and high-power spacecraft thermal control system. Aerospace vapor compression heat pump operates in the microgravity environment. Microgravity vapor compression heat pump adaptability is the key to a vapor compression heat pump technology aerospace research and development. The evaporator is a key component of the vapor compression heat pump.By calculating vapor compression heat pump evaporator to explore its gravity-independent conditions and get gravity-independent critical velocity and critical diameter at different evaporation temperatures and under different flow rates. The results showed that the minimum critical velocity in the evaporator gravity-independent region in 1.45-1.5 m·s^-1. The maximum critical diameter increases with cooling capacity, and cooling capacity from 50 W to 300 W, the critical diameter from 0.42 mm to 1.02 mm.

Key words: microgravity, gravity-independent, critical diameter, critical velocity

摘要： 蒸汽压缩热泵在高温环境和大功率航天器热控系统中具有很好的应用前景。航天蒸汽压缩热泵运行在微重力环境中，蒸汽压缩热泵的微重力适应性是航天蒸汽压缩热泵研发的关键技术。蒸发器是蒸汽压缩热泵的关键部件，为了探究蒸发器的重力无关条件，进行了蒸汽压缩热泵蒸发器的重力无关性计算，获得了不同蒸发温度、不同流速下蒸发器的重力无关临界流速和临界直径。结果表明，蒸发器处于重力无关区的最小临界流速在1.45～1.5 m·s^-1。最大临界直径随制冷量的增加而增加，制冷量从50 W变为300 W，临界直径由0.42 mm变为1.02 mm。

关键词: 微重力, 重力无关性, 临界直径, 临界流速