Patterned Quasi-Liquid Surfaces for Condensation of Low Surface Tension Fluids

Dylan Boylan, Deepak Monga, Zongqi Guo, Pavan Sai Dosawada, Li Shan, Pengtao Wang, Xianming Dai

Research output: Contribution to journalArticlepeer-review

5 Scopus citations

Abstract

Extensive research concerns dropwise condensation of low surface tension fluids to promote energy efficiency and decarbonization in thermal energy systems. However, it is challenging as these fluids typically result in filmwise condensation. Drawing inspiration from the Namib desert beetle that enhances condensation through patterned wettability, conventional beetle-inspired surfaces excel in water condensation but flood when condensing low surface tension fluids. In this work, a patterned quasi-liquid surface is reported that achieves exceptional dropwise condensation of low surface tension fluids. The surface consists of alternating stripes with low surface energy, that is, a perfluoropolyether (PFPE) and fluorinated quasi-liquid surface (FQLS), that shows ultralow contact angle hysteresis for ethanol and hexane. The PFPE stripes are slightly more slippery, acting as slippery bridges that accelerate droplet coalescence and removal. It is experimentally demonstrated that the striped PFPE-FQLS pattern exhibits a heat transfer coefficient 85%, 330%, and 550% higher than that of PFPE, fluorinated silane, and filmwise condensation, respectively. This study reveals that a high contact angle is desired to sustain dropwise condensation, irrespective of contact angle hysteresis. These findings provide a new paradigm for promoting the dropwise condensation of low surface tension fluids and offer valuable insights into surface design for energy sustainability.

Original languageEnglish
Article number2400194
JournalAdvanced Functional Materials
Volume34
Issue number33
DOIs
StatePublished - Aug 14 2024

Funding

D.M., Z.G., and X.D. gratefully acknowledge the National Science Foundation Faculty Early Career Development Program (Award No. 2044348). L.S. was supported by the startup funds at The University of Texas at Dallas (UT Dallas). This project was partially funded by the UT Dallas Seed Program for Interdisciplinary Research. D.B. was supported by the U.S. Department of Energy Innovation in Buildings (IBUILD) Graduate Research Fellowship (Contract No. DE\u2010AC05\u201000OR22725 and DE\u2010SC0014664). Special thanks to UT Dallas cleanroom staff Alexandra Joshi\u2010Imre and Audrey Hammack for their help in ellipsometry and AFM measurements. The University of Texas at Dallas\u2019 effort was performed in part under an appointment to the Building Technologies Office (BTO) IBUILD\u2010 Graduate Research Fellowship administered by the Oak Ridge Institute for Science and Education (ORISE) and managed by Oak Ridge National Laboratory (ORNL) for the U.S. Department of Energy (DOE). ORISE was managed by Oak Ridge Associated Universities (ORAU). All opinions expressed in this paper are the author's and do not necessarily reflect the policies and views of DOE, EERE, BTO, ORISE, ORAU, or ORNL.

Keywords

  • Quasi-liquid surface
  • condensation
  • heat transfer
  • low surface tension

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