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Effect of functional surfaces with gradient mixed wettability on flow boiling in a high aspect ratio microchannel

Ebrahimpour Ahmadi, Vahid and Aboubakri, Akam and Sadaghiani, Abdolali Khalili and Sefiane, Khellil and Koşar, Ali (2020) Effect of functional surfaces with gradient mixed wettability on flow boiling in a high aspect ratio microchannel. Fluids, 5 (4). ISSN 2311-5521

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Official URL: http://dx.doi.org/10.3390/fluids5040239

Abstract

Flow boiling is one of the most effective phase-change heat transfer mechanisms and is strongly dependent on surface properties. The surface wettability is a crucial parameter, which has a considerable effect on the heat transfer performance, particularly in flow boiling. The contact angle determines the number of nucleation sites as well as bubble dynamics and flow patterns. This study introduces three new generation mixed wettability surfaces and compares them with a wholly hydrophobic surface reference sample, in flow boiling in a high aspect ratio microchannel. The mixed wettability substrates have five regions as fully Al2O3, (hydrophobic zone) region, three different patterned configurations with various A* values, and fully SiO2 (hydrophilic zone) region, where A* is defined as A Al2O3/A total (hydrophobicity ratio). Boiling heat transfer results were obtained for each surface at various wall heat fluxes and three different mass fluxes. According to the obtained results, significant enhancements in heat transfer (by up to 56.7%) could be obtained with biphilic surfaces compared to the reference sample (hydrophobic surface). Performed flow visualization proves that the tested biphilic surfaces enhance heat transfer by reducing the bubbly flow regime and extending the slug regime.

Item Type:Article
Uncontrolled Keywords:flow boiling; mixed wettability; boiling heat transfer coefficient; flow regime
Subjects:UNSPECIFIED
ID Code:41284
Deposited By:Abdolali Khalili Sadaghiani
Deposited On:19 Dec 2020 17:49
Last Modified:19 Dec 2020 17:49

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