Review on state-of-the-art research in pool and flow boiling under microgravity

With the continuous development of space science and technology, the expansion of astronaut planetary bases and utilization of extraterrestrial resources have become possible. Space thermal management systems and life support systems are essential for astronaut survival and stable operation of space platforms. This paper reviews the literature on two-phase flow and heat transfer performance under microgravity. The purpose of the present work is to collect and collate the key data of microgravity pool and flow boiling in the literature and summarize the typical differences in two-phase boiling, including two-phase flow pressure drop, heat transfer coefficient, critical heat flux, and flow patterns between normal gravity and microgravity conditions. Comparing the data from the available literature, a general deterioration in the heat transfer in both pool and flow boiling was observed under microgravity, which may be caused by the increase in bubble size and the delayed detachment period. Meanwhile, larger pressure drops and thicker liquid films were observed under microgravity diabatic conditions. The investigation results show that although there are abundant experimental data in microgravity, the lack of correlations and mechanistic models of related theories and inconsistent experimental conclusions have compromised the process of establishing space thermal management systems. The conclusion of the present review is expected to provide insights into the efficient utilization of microgravity pool and flow boiling, and provide reliable recommendations for future space thermal management systems with higher energy efficiency and smaller weight and volume.