Condensation on Composite V-Shaped Surface with Different Gravity in Nanoscale
B Xu and ZQ Chen, MICROGRAVITY SCIENCE AND TECHNOLOGY, 31, 603-613 (2019).
The model of water vapor condensation on a composite V-shaped surface with multi wettability gradients was built and the condensation process with different gravity was studied by molecular dynamics to find out whether this model could control the condensation mode and accelerate the condensate drainage from the micro-perspective. With the absence of gravity, the simulation results indicated that the condensation mode could be controlled as a dropwise condensation. What's more, the movement of condensate nano-droplet also could be controlled, which was helpful for increasing the efficiency of condensate drainage. The temperature of hot wall was largest while it was smallest for cold wall. The temperature of water was in the middle. The result was in accordance with the law of energy conservation. However, the condensation process was different with the effect of gravity. It can be concluded that the condensation process was much quicker with greater gravity, leading to the larger condensation rate. The temperature of cold wall and water were larger than that of hot wall, especially for greater gravity. It was because the part of energy generated by gravity transferred to the thermal energy of water and cold wall, and the other part transferred to the kinetic energy of water. The gravitational potential energy and kinetic energy increased with greater gravity, while the thermal energy increased first and then decreased, corresponding well with the final temperature of condensation process with different gravity. The results will provide a microcosmic mechanism for space experiment and guidance for space system drainage.
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