Recently, micro- or nano- structured surfaces haven been developed to enhance condensation heat transfer, water harvesting and self-cleaning. However, at large subcoolings, condensate floods the subcooled substrate, thus deteriorating the heat transfer efficiency. Here, the superhydrophobic surfaces with micropillared and nanopillared structures are proposed to enhance heat transfer at large subcoolings. The influence of micropillar spacing and surface subcooling on the droplet dynamics and heat transfer performance is experimentally investigated using microscopic visualization techniques. In addition, the microscopic modeling of condensation heat transfer on the microstructured surfaces is performed using the mesoscopic lattice Boltzmann method. The results demonstrate that the droplet size distribution on the micropillared surface is significantly smaller over that of the nanostructured surface. The heat transfer coefficient decreases with the increase of micropillar spacing. As the subcooling rises, although the condensate floods the substrate, the heat transfer coefficient of the S10R30 (S10R30 represents the micropillar arrays with s = 10 μm and 2r = 60 μm) surface is enhanced by 26.4% compared to the hydrophobic nanostructured surface. This is because the height of liquid film is the same of order of magnitude as the micropillars, reducing the thermal resistance caused by the liquid layer. Combining environmental scanning electron microscope (ESEM) observations and LB simulation results, it is concluded that the droplets first nucleate at the bottom corner of micropillars. In addition, the condensate droplets merge to form a film, fill the micropillar gaps, and cover the entire micropillars, leading to a sharp decrease in heat flux. These findings provide a theoretical and experimental guidance for the development of condensing surfaces to enhance heat transfer.

最近，已经开发出微米或纳米结构的表面来增强冷凝传热、集水和自清洁。然而，在大的过冷度下，冷凝水会淹没过冷的基材，从而降低传热效率。在这里，提出了具有微柱和纳米柱结构的超疏水表面以增强大过冷度下的传热。使用显微可视化技术通过实验研究了微柱间距和表面过冷对液滴动力学和传热性能的影响。此外，微结构表面上冷凝传热的微观建模是使用介观晶格玻尔兹曼方法进行的。结果表明，微柱表面上的液滴尺寸分布明显小于纳米结构表面的液滴尺寸分布。传热系数随着微柱间距的增加而降低。随着过冷度的升高，虽然冷凝水淹没基板，但 S10R30 的传热系数（S10R30 代表微柱阵列s = 10 μm 和 2 r  = 60 μm) 表面与疏水性纳米结构表面相比增强了 26.4%。这是因为液膜的高度与微柱处于同一数量级，降低了液层引起的热阻。结合环境扫描电子显微镜 (ESEM) 观察和 LB 模拟结果，得出结论，液滴首先在微柱的底角成核。此外，冷凝液滴合并形成薄膜，填充微柱间隙并覆盖整个微柱，导致热通量急剧下降。这些发现为开发冷凝表面以增强传热提供了理论和实验指导。