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This content will become publicly available on July 18, 2018

Title: Tuning Superhydrophobic Nanostructures To Enhance Jumping-Droplet Condensation

It was recently discovered that condensation growing on a nanostructured superhydrophobic surface can spontaneously jump off the surface, triggered by naturally occurring coalescence events. Many reports have observed that droplets must grow to a size of order 10 μm before jumping is enabled upon coalescence; however, it remains unknown how the critical jumping size relates to the topography of the underlying nanostructure. Here, we characterize the dynamic behavior of condensation growing on six different superhydrophobic nanostructures, where the topography of the nanopillars was systematically varied. The critical jumping diameter was observed to be highly dependent upon the height, diameter, and pitch of the nanopillars: tall and slender nanopillars promoted 2 μm jumping droplets while short and stout nanopillars increased the critical size to over 20 μm. The topology of each surface is successfully correlated to the critical jumping diameter by constructing an energetic model that predicts how large a nucleating embryo needs to grow before it can inflate into the air with an apparent contact angle large enough for jumping. Furthermore, by extending our model to consider any possible surface, it is revealed that properly designed nanostructures should enable nanometric jumping droplets, which would further enhance jumping droplet condensers formore » heat transfer, anti-fogging, and anti-frosting applications.« less
Authors:
 [1] ; ORCiD logo [2] ;  [1] ; ORCiD logo [2] ; ORCiD logo [1]
  1. Virginia Polytechnic Inst. and State Univ. (Virginia Tech), Blacksburg, VA (United States). Dept. of Biomedical Engineering and Mechanics
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Cener for Nanophase Materials Science
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
ACS Nano
Additional Journal Information:
Journal Volume: 11; Journal Issue: 8; Journal ID: ISSN 1936-0851
Publisher:
American Chemical Society (ACS)
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE Office of Science (SC)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; coalescence; condensation; critical jumping size; jumping droplets; optimizing nanostructure design; superhydrophobic
OSTI Identifier:
1394224