Effect of wettability on nucleate boiling

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dc.contributor.author Valente, T.
dc.contributor.author Teodori, E.
dc.contributor.author Moreira, A.L.N.
dc.contributor.upauthor Moita, A.S.
dc.date.accessioned 2016-07-19T07:15:24Z
dc.date.available 2016-07-19T07:15:24Z
dc.date.issued 2015
dc.description.abstract Papers presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, South Africa, 20-23 July 2015. en_ZA
dc.description.abstract Heat transfer enhancement at liquid-solid interfaces is often achieved by modifying the surface properties. However, deep efforts to describe the actual role of surface modification only started at the 1980’s and much work has left undone since then. The wettability is a key parameter governing heat, mass and momentum transport at liquid-solid interfaces. However it is usually quantified using macroscopic quantities, which cannot be related with the micro-and-nano-scale phenomena occurring at the interface. In this context, the present paper revises the potential and limitations of using macroscopic apparent contact angles to predict the wetting regimes. Then, these angles are used to relate the wetting regimes with bubble dynamics and heat transfer processes occurring at pool boiling. The results show that the macroscopic angles are useful to establish general trends and differentiate bubble dynamics behaviour occurring for opposite wetting regimes. However, milder wetting changes occurring within each regime, caused, for instance, by surface topography are not well captured by the apparent angle, as the surface topography is not scaled to affect this macroscopic angle, although it can clearly influence the bubble formation and departure mechanisms and, consequently the heat transfer coefficients. In line with this, the concept of the micro-scale contact angle, as introduced by Phan et al. [1] is used here together with a geometrical parameter to include the effect of surface topography, to describe the role of the wettability on bubble dynamics. Based on this analysis, a multi-scale approach is proposed to include the role of wettability on correlations predicting the pool boiling heat transfer coefficients. en_ZA
dc.description.librarian am2016 en_ZA
dc.format.medium PDF en_ZA
dc.identifier.citation Valente T, Teodori E, Moita AS & Moreira ALN 2015, 'Effect of wettability on nucleate boiling', Paper presented to the 11th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, 2015. en_ZA
dc.identifier.issn 97817759206873
dc.identifier.uri http://hdl.handle.net/2263/55912
dc.language.iso en en_ZA
dc.publisher International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics en_ZA
dc.rights © 2015 University of Pretoria. All rights reserved. The copyright in this work vests in the University of Pretoria. No part of this work may be reproduced or transmitted in any form or by any means, without the prior written permission of the University of Pretoria. en_ZA
dc.subject Heat transfer en_ZA
dc.subject Surface modification en_ZA
dc.subject Wettability en_ZA
dc.subject Pool boiling en_ZA
dc.title Effect of wettability on nucleate boiling en_ZA
dc.type Presentation en_ZA


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