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Dropwise Condensation of Low Surface Tension Fluids on Omniphobic Surfaces

Published

Author(s)

John H. Scott, Konrad Rykaczewski, Adam T. Paxson, Matthew E. Staymates, Marlon L. Walker, Xiaoda Sun, Sushant Anand, Siddarth Srinivasan, Gareth H. McKinley, Jeff Chinn, Kripa Varanasi

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 fluorocarbon refrigerants, carbon dioxide, and methane are used extensively in a number of industrial applications, and the development of passive means for increasing their condensation heat transfer coefficients has potential for efficiency enhancements. Here we investigate the condensation behavior of a variety of liquids with surface tensions in the range of 12 mN/m to 28 mN/m on three types of omniphobic surfaces: smooth oleophobic, re-entrant superomniphobic, and lubricant-impregnated surfaces. We demonstrate that only smooth oleophobic and lubricant-impregnated surfaces can promote dropwise condensation of the majority of these fluids. However, 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 estimate at least a two to four-fold improvement in the heat transfer coefficient.
Citation
Nature - Scientific Reports

Keywords

oleophobic, heat transfer coefficient, ESEM, in-situ electron microscopy, lubricant-impregnated surfaces

Citation

Scott, J. , Rykaczewski, K. , Paxson, A. , Staymates, M. , Walker, M. , Sun, X. , Anand, S. , Srinivasan, S. , McKinley, G. , Chinn, J. and Varanasi, K. (2014), Dropwise Condensation of Low Surface Tension Fluids on Omniphobic Surfaces, Nature - Scientific Reports (Accessed October 17, 2021)
Created March 5, 2014, Updated February 19, 2017