Heat Transfer through a Condensate Droplet on Hydrophobic and Nanostructured Superhydrophobic Surfaces

Shreyas Chavan, Hyeongyun Cha, Daniel Orejon, Kashif Nawaz, Nitish Singla, Yip Fun Yeung, Deokgeun Park, Dong Hoon Kang, Yujin Chang, Yasuyuki Takata, Nenad Miljkovic

Research output: Contribution to journalArticle

Abstract

Understanding the fundamental mechanisms governing vapor condensation on nonwetting surfaces is crucial to a wide range of energy and water applications. In this paper, we reconcile classical droplet growth modeling barriers by utilizing two-dimensional axisymmetric numerical simulations to study individual droplet heat transfer on nonwetting surfaces (90° < θa < 170°). Incorporation of an appropriate convective boundary condition at the liquid-vapor interface reveals that the majority of heat transfer occurs at the three phase contact line, where the local heat flux can be up to 4 orders of magnitude higher than at the droplet top. Droplet distribution theory is incorporated to show that previous modeling approaches underpredict the overall heat transfer by as much as 300% for dropwise and jumping-droplet condensation. To verify our simulation results, we study condensed water droplet growth using optical and environmental scanning electron microscopy on biphilic samples consisting of hydrophobic and nanostructured superhydrophobic regions, showing excellent agreement with the simulations for both constant base area and constant contact angle growth regimes. Our results demonstrate the importance of resolving local heat transfer effects for the fundamental understanding and high fidelity modeling of phase change heat transfer on nonwetting surfaces.

Original languageEnglish (US)
Pages (from-to)7774-7787
Number of pages14
JournalLangmuir
Volume32
Issue number31
DOIs
StatePublished - Aug 9 2016

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics
  • Surfaces and Interfaces
  • Spectroscopy
  • Electrochemistry

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    Chavan, S., Cha, H., Orejon, D., Nawaz, K., Singla, N., Yeung, Y. F., Park, D., Kang, D. H., Chang, Y., Takata, Y., & Miljkovic, N. (2016). Heat Transfer through a Condensate Droplet on Hydrophobic and Nanostructured Superhydrophobic Surfaces. Langmuir, 32(31), 7774-7787. https://doi.org/10.1021/acs.langmuir.6b01903