Abstract

Condensation, a process in which the phase changes from vapor to liquid, plays a crucial role in various industrial systems. So far, several techniques have been proposed to improve the characteristics of condensation. The manipulation of the wettability of a surface is a novel scheme which reduces the heat resistance of the droplets on the surface. The present study experimentally explored the effect of hybrid hydrophilic–hydrophobic surfaces on the formation of primary nucleation, the movement of droplets, and heat transfer. The hydrophobic and hybrid surfaces fabricated by sol-gel and deep coating method. Three distinct surfaces were considered including (i) a hydrophobic surface, (ii) a hybrid hydrophilic–hydrophobic surface with a vertical arrangement (HHSVA), and (iii) a hybrid hydrophilic–hydrophobic surface with a horizontal arrangement (HHSHA). It was found that the HHSVA markedly enhanced the heat and mass transfer compared with the hydrophobic and the HHSHA configurations. Compared with that of the hydrophobic surface, the heat transfer of the HHSVA and the HHSHA increased by 31.9% and decreased by 25.9%, respectively. Then, the heat transfer on these hybrid surfaces depends on the orientation of surfaces. The optimized orientation can increase the heat transfer and improve the droplet’s dynamic parameter on hybrid surfaces.

摘要

冷凝是一种从蒸汽到液体的相变过程，在各种工业系统中起着至关重要的作用。到目前为止，已经提出了几种技术来改善冷凝特性。控制表面的润湿性是一种新颖的方案，可降低表面上液滴的热阻。本研究通过实验探索了亲水-疏水杂化表面对初级成核形成、液滴运动和传热的影响。通过溶胶-凝胶和深层涂层法制备的疏水性和杂化表面。考虑了三个不同的表面，包括（i）疏水表面，（ii）具有垂直排列的混合亲水 - 疏水表面（HHSVA），(iii) 具有水平排列的亲水-疏水杂化表面 (HHSHA)。结果发现，与疏水和 HHSHA 配置相比，HHSVA 显着增强了传热和传质。与疏水表面相比，HHSVA 和 HHSHA 的传热分别增加了 31.9% 和减少了 25.9%。然后，这些混合表面上的热传递取决于表面的方向。优化的方向可以增加传热并改善液滴在混合表面上的动态参数。分别。然后，这些混合表面上的热传递取决于表面的方向。优化的方向可以增加传热并改善液滴在混合表面上的动态参数。分别。然后，这些混合表面上的热传递取决于表面的方向。优化的方向可以增加传热并改善液滴在混合表面上的动态参数。