Contrasting suspended covers reveal the impact of an artificial monolayer on heat transfer processes at the interfacial boundary layer

Pittaway, P. and Martínez-Alvarez, V. and Hancock, N. (2015) Contrasting suspended covers reveal the impact of an artificial monolayer on heat transfer processes at the interfacial boundary layer. Water Science and Technology, 72 (9). pp. 1621-1627. ISSN 0273-1223

Abstract

The highly variable performance of artificial monolayers in reducing evaporation from water storages has been attributed to wind speed and wave turbulence. Other factors operating at the interfacial boundary layer have seldom been considered. In this paper, two physical shade covers differing in porosity and reflectivity were suspended over 10 m diameter water tanks to attenuate wind and wave turbulence. The monolayer octadecanol was applied to one of the covered tanks, and micrometeorological conditions above and below the covers were monitored to characterise diurnal
variation in the energy balance. A high downward (air-to-water) convective heat flux developed under the black cover during the day, whereas diurnal variation in the heat flux under the more reflective, wind-permeable white cover was much less. Hourly air and water temperature profiles
under the covers over 3 days when forced convection was minimal (low wind speed) were selected for analysis. Monolayer application reduced temperature gain in surface water under a downward convective heat flux, and conversely reduced temperature loss under an upward convective heat flux. This ‘dual property’ may explain why repeat application of an artificial monolayer to retard evaporative loss (reducing latent heat loss) does not inevitably increase water temperature.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to published version in accordance with the copyright policy of the publisher.
Faculty / Department / School: Current - Faculty of Health, Engineering and Sciences - School of Agricultural, Computational and Environmental Sciences
Date Deposited: 22 Apr 2016 04:10
Last Modified: 28 Jul 2016 02:42
Uncontrolled Keywords: free convection, liquid thermal boundary layer, octadecanol, physical covers,water skin layer
Fields of Research : 05 Environmental Sciences > 0502 Environmental Science and Management > 050299 Environmental Science and Management not elsewhere classified
Socio-Economic Objective: D Environment > 96 Environment > 9609 Land and Water Management > 960999 Land and Water Management of Environments not elsewhere classified
Identification Number or DOI: 10.2166/wst.2015.379
URI: http://eprints.usq.edu.au/id/eprint/28174

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