Study on pool boiling heat transfer in microgravity

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 R113 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.