Ho, Zhi Yong (2021) Development And Performance Evaluation Of Fresnel Lens And Phase Change Material Assisted Portable Solar Desalination System For Fresh Water Production. Master dissertation/thesis, UTAR.
Abstract
Passive solar still is one of the solutions on water scarcity in coastal and rural regions due to its uncomplicated design as well as its least demand for electrical energy. However, passive solar still often has low efficiency and productivity due to its limitation on enhancement approach. Concentrated solar power (CSP) is one of the well-known features being used on solar desalination. Reflective CSPs are mostly used on active solar still as it require solar tracker for its high sensitivity to solar flux. In this study, a less sensitive refraction based CSP feature is introduced to improve the performance of passive solar stills. The performance evaluation in terms of efficiency and productivity was conducted on 2 differently designed passive double slope single basin solar still coupled with Fresnel lens (FRL). Both prototypes show similar trends in augmentation of efficiency and productivity. The theoretical values of daily water yield show a good match with the experimental values. The highest water yield recorded from a prototype coupled with Fresnel lens is 3.19 L/m2day. With FRL, the efficiency of the prototype has reached to 37% from 28% for the conventional design. An increase in productivity (g/kJ) by 60% as compared to the conventional still is also observed. Further studies are conducted to identify the effect of Phase Change Material (PCM) being used as energy storage of the designed passive solar still. PCM alone stabilize the process with an enhanced productivity. However, when coupled with Fresnel lens, the existing design of PCM filled tubes placed in the solar still’s basin did not show significant improvement due to heat loss to the surrounding. The collected freshwater from the 35,000 ppm saline solution produced by the prototypes is of very high quality and complies well with the World Health Organization (WHO) standard.
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