Low-Cost, Low-Energy Concentrate Water Desalination Using Heat Recuperative Solar Still with Concentrating Solar Technology

Published Date:
October 2020

Authors:
Sarada Kuravi, Pei Xu, Krishna Kota, Young-Ho Park, Huiyao Wang

Abstract:
This work investigated new solar collection and heat transport approaches to significantly enhance the solar input and phase change processes in a solar still to realize high desalination rates. This research studied the following novel techniques and analyzed their potential to improve the productivity of a solar still: (i) use of an external point-focusing Fresnel lens to amplify solar insolation (or energy input per m2 to achieve boiling); (ii) use of a superhydrophobic surface on glass cover to reduce the water layer thickness (and hence improve condensation); (iii) use of hydrophilic surfaces to enhance the heat transfer rate by increasing wettability at the basin-water interface; and (iv) use of interfacial evaporation materials to enhance evaporation (water-vapor interface). The effect of each of these enhancements was analyzed separately using systematic experiments and analytical modeling. It was found that the Fresnel lens improved productivity by 467% under the conditions tested. The hydrophobic glass cover coatings showed lower productivity compared to no coatings. Increasing wettability on an aluminum surface showed a 15-20% increase in water productivity. The evaporation efficiency using 10CBMCE under 5-suns was 1.53 times that of evaporation without the photothermal membrane.

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Keywords:
Solar still; Water purification; Concentrating solar power; Interfacial evaporation