IAHR, founded in 1935, is a worldwide independent member-based organisation of engineers and water specialists working in fields related to the hydro-environmental sciences and their practical application. Activities range from river and maritime hydraulics to water resources development and eco-hydraulics, through to ice engineering, hydroinformatics, and hydraulic machinery.
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You are here : eLibrary : IAHR World Congress Proceedings : 34th Congress - Brisbane (2011) : THEME 1: Extremes and Variability : Laboratory assessment of the performance of porous coverings in evaporation mitigation
Laboratory assessment of the performance of porous coverings in evaporation mitigation
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Loss of water resources due to evaporation is an issue of ongoing concern in Australia. Evaporation mitigation devices are being developed. These include floating units of various shapes which reduce the exposed evaporative surface area. This paper describes a preliminary evaluation of the effectiveness and efficiency of floating modular devices with different surface textures and therefore different magnitudes of adhesion between these device surfaces and water. Some materials with high adhesion to water, will draw up the water onto the device, whereas other materials are not easily wetted and will repel water. The evaporation experiments performed included an open water control test, and three floating modular device tests. The three devices were tennis balls; which represent hydrophilic materials, smooth polyethylene balls; which represent hydrophobic materials, and smooth polyethylene palls with a slime-mould growth; which represent hydrophilic materials which have aged and acquired a biological surface growth. Once essential corrections to ambient relative humidity and temperature effects were included, analysis of the test results showed that floating tennis balls increased the amount of evaporation by a factor of 1.33, whereas both the clean and slime-mould coated polyethylene balls reduced the rate of evaporation by about 65%. It was possible to quantify an adhesion coefficient to account for the increase in evaporation with respect to the planar surface area of water. These factors were 4.5, 2.1 and 2.0 for the tennis ball, smooth polyethylene ball and slime-mould coated polyethylene ball tests respectively. The impacts of adhesion are significant and need to be considered in the assessment of strategies to mitigate evaporation at the surface of open water bodies.
File Size : 475,976 bytes
File Type : Adobe Acrobat Document
Chapter : IAHR World Congress Proceedings
Category : 34th Congress - Brisbane (2011)
Article : THEME 1: Extremes and Variability
Date Published : 08/08/2012
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