ABSTRACT The Gibbs free energy barrier for heterogeneous nucleation of a condensed droplet on a rough surface changes significantly with changes of humidity content in the condensing environment. The influence of environmental factors (ambient temperature and relative humidity) and substrate characteristics (topology, surface chemistry, and substrate temperature) on atmospheric condensation phenomenon is very important to elucidate the condensed droplet wetting state and condensate harvesting applications. Condensation from the humid air has been reported for plain silicon and fabricated nanopillar surfaces to facilitate condensate harvesting. Droplet growth and size distributions were recorded for 90 min. Spherical droplets condensed on the silicon surfaces and irregular-shaped droplets were observed on the nanopillar surfaces due to the pinning effect of the pillars. The effect of droplet pinning on coalescence events has been described based on the energy balance for the condensed droplets. A mathematical model reveals that certain dimensional combinations (pillar pitch, pillar diameter, and pillar height) of the nanopillar geometry are required to exhibit the pinning mechanism for condensed droplets. Regeneration of droplets was observed at void spaces generated from coalescence events. The growth of individual droplets was tracked over multiple time and length scales, starting from nucleation to get further insight into the direct growth and coalescence mechanisms. Abbreviation: ESEM: Environmental Scanning Electron Microscope; HCP: Hexagonal Closed-Packed; MPL: Microsphere Photolithography; RH: Relative Humidity

中文翻译：

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纳米柱表面大气冷凝过程中的液滴生长动力学

摘要 粗糙表面上凝结液滴的异相成核的吉布斯自由能垒随着凝结环境中湿度含量的变化而显着变化。环境因素（环境温度和相对湿度）和基材特性（拓扑、表面化学和基材温度）对大气凝结现象的影响对于阐明凝结液滴润湿状态和凝结水收集应用非常重要。据报道，湿空气中的冷凝可用于普通硅和制造的纳米柱表面，以促进冷凝物收集。记录液滴生长和尺寸分布 90 分钟。由于柱子的钉扎效应，在硅表面上凝结的球形液滴和在纳米柱表面上观察到不规则形状的液滴。基于凝聚液滴的能量平衡描述了液滴钉扎对聚结事件的影响。数学模型表明，需要纳米柱几何形状的某些尺寸组合（柱间距、柱直径和柱高度）才能表现出凝聚液滴的钉扎机制。在由聚结事件产生的空隙空间观察到液滴的再生。在多个时间和长度尺度上跟踪单个液滴的生长，从成核开始，以进一步了解直接生长和聚结机制。缩写：ESEM：环境扫描电子显微镜；卫生防护中心：六角密排；MPL：微球光刻；RH：相对湿度