Title

Transient Heat Transfer of Impinging Jets on Superheated Wetting and Non-Wetting Surfaces

Keywords

SuperhydrophobicJet impingementBoiling heat transfer

Abstract

Superhydrophobic (SH) surfaces possess desirable anti-fouling properties due to low wettability, but have also been shown to reduce heat transfer to subcooled water in impinging jet scenarios. In this work, superheated silicon substrates with varying wettability (hydrophilic or HPi, hydrophobic or HPo, SH) are quenched by an impinging water jet, where the substrate temperature is above the saturation temperature. Silicon wafers are either oxidized to create HPi surfaces, coated with Teflon to make the surface HPo, or plasma-etched and coated to create the necessary micro-texture for SH conditions. All wafers are integrated with an electric resistance heater and then heated to temperatures of 200–320 ∘" role="presentation" style="box-sizing: border-box; margin: 0px; padding: 0px; display: inline-block; line-height: normal; font-size: 16.2px; word-spacing: normal; overflow-wrap: normal; white-space: nowrap; float: none; direction: ltr; max-width: none; max-height: none; min-width: 0px; min-height: 0px; border: 0px; position: relative;">∘C before impingement with an axisymmetric room temperature water jet of varying specified flow rates yielding jet Reynolds numbers between 6000 and 18,000. High-speed visual data is collected, showing how the lamellar liquid contact region, limited by thermal breakup due to boiling, grows radially as the surface cools to temperatures below saturation. This data is correlated to temperature data recorded on the back side of the wafer using a thermal camera. Results of this study confirm previous conjecture that surface wettability can alter maximum heat flux, which is quantified here for the described scenario by up to 40%, and can also affect jet thin film spreading by up to 50%. Increasing initial surface temperature decreases thin film spreading rate on all surfaces, and increases heat transfer on all but the SH surfaces. Increasing Reynolds number yields an increase in heat flux, and affects both the thin film spreading rate as well as the maximum radius of the thin film region.

Original Publication Citation

Butterfield, D. J., Crockett, J., Maynes, R. D., and Iverson, B. D., 2021, “Transient heat transfer of impinging jets on superheated wetting and non-wetting surfaces,” International Journal of Heat and Mass Transfer, Vol. 175, p. 121056. DOI: 10.1016/j.ijheatmasstransfer.2021.121056

Document Type

Peer-Reviewed Article

Publication Date

2021-8

Publisher

International Journal of Heat and Mass Transfer

Language

English

College

Ira A. Fulton College of Engineering

Department

Mechanical Engineering

University Standing at Time of Publication

Associate Professor

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