title: Dropwise condensation of low surface tension fluids on omniphobic surfaces.
abstract: Compared to the significant body of work devoted to surface engineering for promoting dropwise condensation heat transfer of steam, much less attention has been dedicated to fluids with lower interfacial tension. A vast array of low-surface tension fluids such as hydrocarbons, cryogens, and fluorinated refrigerants are used in a number of industrial applications, and the development of passive means for increasing their condensation heat transfer coefficients has potential for significant efficiency enhancements. Here we investigate condensation behavior of a variety of liquids with surface tensions in the range of 12 to 28 mN/m on three types of omniphobic surfaces: smooth oleophobic, re-entrant superomniphobic, and lubricant-impregnated surfaces. We demonstrate that although smooth oleophobic and lubricant-impregnated surfaces can promote dropwise condensation of the majority of these fluids, re-entrant omniphobic surfaces became flooded and reverted to filmwise condensation. We also demonstrate that on the lubricant-impregnated surfaces, the choice of lubricant and underlying surface texture play a crucial role in stabilizing the lubricant and reducing pinning of the condensate. With properly engineered surfaces to promote dropwise condensation of low-surface tension fluids, we demonstrate a four to eight-fold improvement in the heat transfer coefficient.
authors.affiliation: 1] School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ [2].
authors.forename: Konrad
authors.initials: K
authors.lastname: Rykaczewski
authors.affiliation: 1] Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA [2].
authors.forename: Adam T
authors.initials: AT
authors.lastname: Paxson
authors.affiliation: Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD.
authors.forename: Matthew
authors.initials: M
authors.lastname: Staymates
authors.affiliation: Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD.
authors.forename: Marlon L
authors.initials: ML
authors.lastname: Walker
authors.affiliation: School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, AZ.
authors.forename: Xiaoda
authors.initials: X
authors.lastname: Sun
authors.affiliation: Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA.
authors.forename: Sushant
authors.initials: S
authors.lastname: Anand
authors.affiliation: Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA.
authors.forename: Siddarth
authors.initials: S
authors.lastname: Srinivasan
authors.affiliation: Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA.
authors.forename: Gareth H
authors.initials: GH
authors.lastname: McKinley
authors.affiliation: Integrated Surface Technologies Inc., Menlo Park, CA.
authors.forename: Jeff
authors.initials: J
authors.lastname: Chinn
authors.affiliation: Material Measurement Laboratory, National Institute of Standards and Technology, Gaithersburg, MD.
authors.forename: John Henry J
authors.initials: JH
authors.lastname: Scott
authors.affiliation: Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA.
authors.forename: Kripa K
authors.initials: KK
authors.lastname: Varanasi