Visualization study of flow condensation in hydrophobic microchannels

Authors

  • Yongping Chen,

    Corresponding author
    1. School of Hydraulic, Energy and Power Engineering, Yangzhou University, Yangzhou, Jiangsu, P.R. China
    2. Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, Jiangsu, P.R. China
    • Correspondence concerning this article should be addressed to Y. Chen at chenyp@yzu.edu.cn.

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  • Chaoqun Shen,

    1. Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, Jiangsu, P.R. China
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  • Mingheng Shi,

    1. Key Laboratory of Energy Thermal Conversion and Control of Ministry of Education, School of Energy and Environment, Southeast University, Nanjing, Jiangsu, P.R. China
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  • George P. Peterson

    1. George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA
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Abstract

A visualization study on flow condensation in hydrophobic rectangular silicon microchannels with hydraulic diameter of approximately 150 μm is conducted. Thin Au film with thickness of 200 nm is sputtered on channel surfaces to create a hydrophobic surface with an equilibrium contact angle of approximately 96°. In addition to traditional droplet flow, droplet-annular compound flow, droplet-injection compound flow, and droplet-bubble/slug compound flow are also observed. The results indicate that injection location is postponed, and injection frequency increases with increasing inlet vapor Reynolds number and condensate Weber number. An empirical correlation of the injection location and injection frequency are presented and discussed. In particular, for a larger inlet vapor Reynolds number, the injection flow is closer to the channel outlet and the condensation heat transfer is enhanced. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1182–1192, 2014

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