微重力池沸腾传热研究

Study on Pool Boiling Heat Transfer in Microgravity

对利用中国返回式卫星搭载开展的两次微重力池沸腾空间实验及地基常重力和落塔短时微重力实验的结果进行了评述.研究发现微重力时丝状加热器沸腾传热会略有强化,而平板加热器则在高热流条件下明显恶化.微重力时,气泡脱落前存在沿加热面的横向运动,加剧了相邻气泡间的合并,合并气泡会在其表面振荡作用下从加热面脱落.Marangoni效应对于微重力气泡行为有重要影响.

Two experiments on pool boiling in microgravity have been conducted aboard the Chinese recoverable satellites. Ground-based experiments have also been performed both in normal gravity and in short-term microgravity in the Drop Tower Beijing. A thin platinum wire and a plain plate were used as heaters, respectively. Steady boiling of Rl13 on the wire was studied with a temperature-controlled heating method, while quasi-steady boiling of FC-72 on the plate was investigated with an exponentially increasing heating voltage. In the first case, slight enhancement of heat transfer is observed in microgravity, while diminution is evident for high heat flux in the second one. Lateral motions of bubbles on the heaters are observed before their departure in microgravity. The surface oscillation of the merged bubbles due to lateral coalescence between adjacent bubbles drives it to detach from the heaters. It＇s also discussed about the Marangoni effect on the bubble behavior.