Dropwise condensation: Experiments and simulations of nucleation and growth of water drops in a cooling system
Dropwise condensation: Experiments and simulations of nucleation and growth of water drops in a cooling system
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DOI：
10.1021/la061901
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发表时间：
2006-10-10
期刊：
影响因子：
3.9
通讯作者：
Dickinson, J. T.
中科院分区：
文献类型：
--
作者：
Leach, R. N.;Stevens, F.;Dickinson, J. T.
通过直接观察和模拟，研究了水蒸气从自然冷却的热水储层到疏水聚合物膜和硅烷化载玻片上的滴状冷凝。所观察到的液滴生长动力学表明，最小的液滴生长主要是由吸附在基板上的水的扩散到液滴周边，而直径大于约50微米的液滴生长主要是由从蒸汽直接沉积到液滴表面上。液滴聚结在确定液滴尺寸分布方面发挥着关键作用，并刺激基底上新的小液滴的成核。将这些增长机制的液滴增长的模拟提供了一个很好的描述所观察到的液滴尺寸分布。由于聚结所起的重要作用，单个液滴生长的细节对最终的液滴尺寸分布影响不大。每单位基底面积的冷凝速率对于最小的液滴特别高，并且可以有助于解释与热交换应用中的逐滴冷凝相对于膜状冷凝相关联的高传热速率。
Dropwise condensation of water vapor from a naturally cooling, hot water reservoir onto a hydrophobic polymer film and a silanized glass slide was studied by direct observation and simulations. The observed drop growth kinetics suggests that smallest drops grow principally by the diffusion of water adsorbed on the substrate to the drop perimeter, while drops larger than about 50 Am in diameter grow principally by direct deposition from the vapor onto the drop surface. Drop coalescence plays a critical role in determining the drop-size distribution and stimulates the nucleation of new, small drops on the substrates. Simulations of drop growth incorporating these growth mechanisms provide a good description of the observed drop-size distribution. Because of the large role played by coalescence, details of individual drop growth make little difference to the final drop-size distribution. The rate of condensation per unit substrate area is especially high for the smallest drops and may help account for the high heat transfer rates associated with dropwise condensation relative to filmwise condensation in heat exchange applications.