Institute of Thermal Science and Technology, Shandong University, Jinan 250061, China.
School of Mechanical Engineering, Shandong University, Jinan 250061, China.
Langmuir. 2022 Sep 13;38(36):11099-11108. doi: 10.1021/acs.langmuir.2c01796. Epub 2022 Aug 29.
Vapor condensation on bioinspired hierarchical nanostructured surfaces with hybrid wettabilities has been investigated using molecular dynamics simulations. A series of hierarchical surfaces consisting of nanocylinder arrays with hydrophilic top and hydrophobic nanopillar arrays are constructed. The results manifest that the condensed nanodroplets undergo three states in the whole water vapor condensation process, and the total condensed atom number on surfaces increases with the increase of nanocylinder diameter (), which indicates that the introduction of hydrophilic nanocylinders is conducive to improving the condensation performance compared with that on the hydrophobic surface patterned with homogeneous nanopillars. However, the nucleation sites on hierarchical nanostructured surfaces are covered by the condensed nanodroplets at the end of condensation, which suppresses the further enhancement of condensation performance. To solve these problems, we add a collection region close to the edge of the nanostructured surface. It is noticed that the condensed nanodroplets can roll into the collection regions gradually during the condensation process, which keeps the nucleation sites on nanostructured surfaces exposed effectively, especially for the cases of 20 Å ≤ ≤ 40 Å. Moreover, the cluster number, the total condensed atom number, and the condensation enhancement efficiency on hierarchical nanostructured surfaces with collection regions at 20 Å ≤ ≤ 40 Å are higher obviously compared with those on surfaces without collection regions. Our study demonstrates that the bioinspired hierarchical nanostructured surface with the collection region is beneficial to boost the vapor condensation performance, which can bring new insights into water vapor condensation.
采用分子动力学模拟研究了具有混合润湿性的仿生分级纳米结构表面上的蒸汽冷凝。构建了一系列由亲水纳米圆柱阵列和疏水纳米柱阵列组成的分级表面。结果表明，在整个水蒸气冷凝过程中，冷凝的纳米液滴经历了三个状态，并且表面上的总冷凝原子数随纳米圆柱直径的增加而增加（），这表明与具有均匀纳米柱图案的疏水表面相比，引入亲水纳米圆柱有利于提高冷凝性能。然而，在冷凝结束时，分层纳米结构表面上的成核位置被冷凝的纳米液滴覆盖，这抑制了冷凝性能的进一步提高。为了解决这些问题，我们在纳米结构表面的边缘附近添加了一个收集区域。注意到，在冷凝过程中，冷凝的纳米液滴可以逐渐滚入收集区域，从而有效地保持纳米结构表面上的成核位置暴露，特别是在 20Å≤≤40Å 的情况下。此外，在 20Å≤≤40Å 的具有收集区域的分层纳米结构表面上的团簇数、总冷凝原子数和冷凝增强效率明显高于没有收集区域的表面。我们的研究表明，具有收集区域的仿生分级纳米结构表面有利于提高蒸汽冷凝性能，这为水蒸气冷凝提供了新的见解。
