A Review of Progress in Condensation and Heat Transfer Research in Microgravity
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摘要: 本文对微重力下膜/滴状冷凝的实验和数值研究进行了全面回顾,涵盖管内/平面冷凝及强化传热机制。结合常/微重力环境下的研究结果,对于管内冷凝换热,采用重力无关准则数(Bond数、Froude数等)判断是否重力影响传热,可通过增加蒸汽质量流速和减小管径减弱重力影响,并总结了微重力冷凝下传热关联式以指导工程设计。对于滴状冷凝,微重力环境下可提高蒸汽速度、使用具有润湿梯度或微/纳米结构的表面结合气流吹扫去除冷凝液滴,实现持续滴状冷凝。目前关于微重力环境下的冷凝实验研究有限,主要受限于长期、连续的微重力实验环境极为难得,应着重关注中国空间站、国际空间站,对长时间的冷凝传热进行实验研究,弥补大量缺乏可重复实验数据的不足,探索重力对冷凝传热的作用机制,为空间两相换热系统提供理论支撑。Abstract: A comprehensive review of experimental and numerical studies of film and droplet condensation in microgravity is presented, covering in-tube and plane condensation as well as enhanced heat transfer mechanisms. For condensing heat transfer in tubes, gravity-independent criterion numbers (Bond number, Froude number, etc.) are used to determine whether gravity affects heat transfer, and the effect of gravity can be attenuated by increasing the mass flow rate of the vapor and reducing the tube diameter. For droplet condensation, continuous droplet condensation in microgravity can be achieved by increasing the vapor velocity, and using surfaces with a wetting gradient or micro/nano structure in combination with airflow purging to remove condensate droplets. Current research on condensation experiments in microgravity is limited, mainly due to the fact that long-term, continuous microgravity experimental are extremely rare. Emphasis should be placed on the Chinese Space Station and the International Space Station to carry out experimental studies of condensation heat transfer over long periods of time, to make up for the large amount of lack of reproducible experimental data, exploring the mechanism of gravity's effect on condensation heat transfer, in order to develop reliable design tools for space station applications.
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Key words:
- Microgravity /
- Space station /
- Film condensation /
- Droplet condensation /
- Enhanced condensation
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