Hierarchical microporous superhydrophobic surfaces with nanostructures enhancing vapor condensation heat transfer

• Published in: Applied thermal engineering 2023-01, Vol.219, p.119527, Article 119527
• Main Authors: Wang, Xin, Xu, Bo, Chen, Zhenqian
• Format: Article
• Language: English
• Subjects: Condensation heat transfer; Droplet jumping; Hierarchical superhydrophobic surface; Lattice Boltzmann method; Surface energy
• ISSN: 1359-4311
• DOI: 10.1016/j.applthermaleng.2022.119527

[Display omitted] •A microporous superhydrophobic surface with nanoblades is fabricated.•The maximum diameter of drops on MN SHS is only half of that on Nano SHS.•Heat transfer coefficient of MN SHS is enhanced by 26.4% over that of Nano SHS.•LB model is used to study the jumping ability of drops on different structured surfaces. A new hierarchical superhydrophobic surface with micropores and nanoblades (MN SHS) is proposed to strengthen the jumping ability of droplets and maintain the high-efficiency droplet jumping condensation at the larger subcoolings. The results demonstrate that the jumping frequency and the proportion of multidroplets merging (n ≥ 8) on the MN SHS are higher than those on the nanostructured superhydrophobic surfaces (Nano SHS). Moreover, the maximum diameter of condensate droplets is only 150 μm, which is approximately 50% smaller compared to the Nano SHS. Spontaneous jumping of condensate droplets is observed on the 40PPI MN SHS (PPI: the average number of pores per inch.) at a subcooling of 16 K; while the droplet jumping condensation occurs at a maximum of 5 K on the Nano SHS. As the subcooling ranges from 5 K to 16 K, the heat transfer coefficient of MN SHS is increased by at least 26.4% compared to the Nano SHS. In addition, lattice Boltzmann model is adopted to simulate the self-propelled jumping behaviors on different structured surfaces. The energy conversion efficiency of drops on the MN SHS is higher compared to that on the Nano SHS. This work will contribute to the potential development of dropwise condensation in energy utilization, petrochemical engineering, thermoelectric cooling and aerospace thermal management systems.