Modelling and Experimental Investigation of the Evaporation Suppression Using Floating Covers in the Presence of Surface Flows

Document Type : Research Article

Authors

1 Department of Mechanical and Mechatronics Engineering, Shahrood University of Technology, Shahrood

2 Department of Civil Engineering, Isfahan University of Technology, Isfahan, Iran

Abstract

The increase in fresh-water demand due to the rapid population growth and climate changes with severe droughts highlights the protection of limited fresh-water resources. In arid regions, evaporation accounts for a significant fraction of losses from water reservoirs. Among different methods for suppressing evaporative loss, the use of modular floating elements offers a simple and reliable technique. Despite numerous studies on application of floating elements, performance of this method in the presence of surface flows is not yet addressed comprehensively. Hence, the present study aims to investigate the effect of surface flows on evaporation from covered reservoirs. For this purpose, a 500-liter water reservoir was covered with white and black balls and a water-pump provided surface flows at different rates. The results show that evaporation decreases monotonically with increasing surface flow rate until a specific flow rate, called optimal flow rate. The increase in surface flow more than this optimal rate results in increase in evaporative loss. Regardless of surface flow condition, the results indicate that the lowest water evaporation occurs for the coverage with white balls while coverage using a mixture of black and white balls and only with black balls showed higher evaporation rates, respectively (the highest evaporation is of course for the uncovered surface). The experimental findings demonstrate that surface flows with appropriate rates can effectively enhance evaporation suppression efficiency of floating elements. Comparison of the modeling results with experimental outputs highlights application of the physically-based energy balance model in estimating surface evaporation for covered and uncovered water surfaces with and without surface flow conditions.

Keywords

Main Subjects

References

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Amirkabir Journal of Mechanical Engineering
Volume 52, Issue 7
October 2020
Pages 1193-2010

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