Enhancing the Long‐Term Robustness of Dropwise Condensation on Nanostructured Superhydrophobic Surfaces by Introducing 3D Conical Microtextures Prepared by Femtosecond Laser

Abstract

Abstract Achieving sustainable dropwise condensation is still a challenge for the industrial applications of bio‐inspired superhydrophobic surfaces in the field of phase‐change heat transfer. In this work, 3D conical microtextures covered by various nanostructures are prepared by utilizing femtosecond laser micromachining and solid–liquid reactions, where the introduction of 3D conical microtextures affected both the early distribution and the subsequent coalescence and departure of condensed droplets. Due to the growth and coalescence of condensed droplets, some merged droplets cannot depart from the surfaces due to the pinning effect caused by the localized micro‐defects of imperfect nanoscale morphology or chemical heterogeneity, thus resulting in the generation of large pinned droplets. The introduction of 3D conical microtextures helps with the departure of these pinned droplets due to the enhanced Laplace expulsion of conical morphology, which inhibits the increase of large droplets and maintains stable dropwise condensation. The results provide an engineering feasible approach to enhance the long‐term robustness of dropwise condensation on superhydrophobic surfaces, thus benefiting the optimal design of practical bio‐inspired superhydrophobic surfaces.

Keywords

• bio‐inspired surfaces
• coalescence‐induced droplet jumping
• dropwise condensation
• femtosecond laser
• superhydrophobic surfaces