Abstract Steam condensation is a ubiquitous phenomenon of phase change that can be encountered in various industrial applications. In practice, the presence of non-condensable gases (NCG) is often inevitable, which can severely deteriorate condensation heat transfer by accumulating in the vicinity of the condensing surface as an additional thermal resistance. In this work, steam condensation heat transfer on a honeycomb-like microporous superhydrophobic surface, which has already been shown to lead to stable coalescence-induced droplet jumping with high heat flux, was studied with NCG concentrations up to ~28%. The superhydrophobic surface, having a nominal pore diameter of ~20 μm, was prepared by a rapid, cost-effective and highly scalable electrodeposition method over the outer surface of thin copper tubes. Condensation experiments were conducted in a visualized vacuum chamber maintaining at a constant pressure of 9.5 kPa. Significant enhancements of condensation heat transfer at the various NCG concentrations were exhibited on such superhydrophobic surface over a wide range of subcooling up to ~35 K, due to the successful realization of droplet jumping in spite of the presence of NCG. The adsorption of NCG into the micropores was elucidated to be a partial reason for prohibition of condensate flooding at relatively high degrees of subcooling.

中文翻译：

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在不凝气体存在下蜂窝状微孔超疏水表面增强蒸汽冷凝传热的可视化研究

摘要 蒸汽冷凝是一种普遍存在的相变现象，在各种工业应用中都会遇到。在实践中，不可冷凝气体 (NCG) 的存在通常是不可避免的，它会在冷凝表面附近作为额外的热阻积聚，从而严重恶化冷凝传热。在这项工作中，研究了蜂窝状微孔超疏水表面上的蒸汽冷凝传热，该表面已被证明可导致稳定的聚结诱导液滴跳跃和高热通量，NCG 浓度高达 ~28%。超疏水表面的公称孔径为~20 μm，是通过快速、经济且可扩展的电沉积方法在细铜管的外表面制备的。冷凝实验在保持 9.5 kPa 恒定压力的可视化真空室中进行。尽管存在 NCG，但由于成功实现了液滴跳跃，因此在高达 ~35 K 的过冷范围内，在这种超疏水表面上表现出在各种 NCG 浓度下冷凝传热的显着增强。NCG 吸附到微孔中被阐明是在相对高的过冷度下禁止凝析油驱的部分原因。尽管存在 NCG，但仍成功实现了液滴跳跃。NCG 吸附到微孔中被阐明是在相对高的过冷度下禁止凝析油驱的部分原因。尽管存在 NCG，但仍成功实现了液滴跳跃。NCG 吸附到微孔中被阐明是在相对高的过冷度下禁止凝析油驱的部分原因。