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Experimental Investigation of Condensation and Freezing Phenomenon on Hydrophilic and Hydrophobic Titanium Nanopillared Glass Surfaces
Heat Transfer Engineering
  • Mohammad Rejaul Haque
  • Chen Zhu
  • Chuang Qu
  • Edward C. Kinzel, Missouri University of Science and Technology
  • Amy Rachel Betz
Abstract

Atmospheric condensation is very important for multiple practical applications such as heat transfer, thermal management, aerospace, and condensate harvesting. Water droplets heterogeneously nucleate on the surfaces when the temperature is below the dew point temperature. The nucleation energy barrier for a condensed droplet varies significantly with the humidity content in the operating environment. The freezing of this condensate is also dependent on the operating conditions and surface properties. This article presents an experimental study of condensation and freezing from humid air with the objective of understanding how the surface morphology and chemistry determines the droplet shape and wetting state. Hexagonal close-packed arrays of titanium (Ti) pillars are patterned using microsphere photolithography (MPL). The Ti nanostructured surface was tested with and without a Teflon© coating to reveal the condensate harvesting, passive freezing, and dropwise condensation applications, respectively. Condensation and freezing tests were conducted in the presence of non-condensable gases (air) with different relative humidity (RH) levels to control the nucleation site density. The experiments showed that droplet growth occurs in the following stages: initial nucleation, direct growth, and coalescence events. By pinning droplets, coalescence is suppressed for the Ti nanopillared surface altering the size distribution of droplets and significantly accelerating the freezing process.

Meeting Name
6th International Conference on Micro and Nano Flows, MNF2018, (2018: Sep. 9-12, 2018, Atlanta, GA)
Department(s)
Mechanical and Aerospace Engineering
Research Center/Lab(s)
Center for Research in Energy and Environment (CREE)
Comments

Published online: 21 Jan 2020

This material is based upon work supported by the National Science Foundation under Grants No. 1604183 and 1653792.

Keywords and Phrases
  • Atmospheric humidity,
  • Coalescence,
  • Condensation,
  • Drops,
  • Freezing,
  • Heat transfer,
  • Humidity control,
  • Morphology,
  • Nanopillars,
  • Nucleation,
  • Polytetrafluoroethylenes,
  • Surface morphology,
  • Titanium,
  • Wetting, Dewpoint temperature,
  • Dropwise condensation,
  • Experimental investigations,
  • Hexagonal close packed,
  • Hydrophilic and hydrophobic,
  • Nanostructured surface,
  • Nucleation site density,
  • Operating environment, Density of gases
Document Type
Article - Conference proceedings
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2020 Taylor & Francis Ltd., All rights reserved.
Publication Date
3-26-2021
Publication Date
26 Mar 2021
Citation Information
Mohammad Rejaul Haque, Chen Zhu, Chuang Qu, Edward C. Kinzel, et al.. "Experimental Investigation of Condensation and Freezing Phenomenon on Hydrophilic and Hydrophobic Titanium Nanopillared Glass Surfaces" Heat Transfer Engineering Vol. 42 Iss. 6 (2021) p. 533 - 548 ISSN: 0145-7632; 1521-0537
Available at: http://works.bepress.com/chen-zhu/33/