Performance Analysis of a Solar Desalination System with Concentrated Solar Power (CSP)

Abstract

Malaysia, being located around the tropical belt, enjoys ample solar exposure throughout the year. Harnessing solar energy for different application is making progress nationwide. Besides extending research on photovoltaic cells; the solar water heating for different purposes is progressing through the past decades. In this paper, performance of a solar still associated with concentrated solar power facilities is presented. In a typical solar still, the solar heat is used to evaporate waste/brackish/saline water (generally termed as feedwater). A basin of the feedwater covered by an inclined transparent cover is placed under the sun to trap the solar heat. The solar heat evaporates the feedwater and the condensate is collected from the inner surface of the transparent cover. In this study, the incident solar irradiation is optimized to produce freshwater from saline/brackish water in a portable solar collector with concentrated solar power (CSP). Fresnel lens has been used as the CSP apparatus. A flat Fresnel lens of size 400 mm x 300 mm with a focal length of 510 mm and light intensity of 92% was attached to concentrate the incident solar irradiation on the inclined transparent cover. Preliminary experiments showed that addition of the Fresnel lens with an optimum tilt of 45° created a "hotspot" in the basin in a particular time of the day and the average condensate production rate increased by 92% compared to that from a bare transparent cover. The distillate from the solar still had a conductivity of 39 μS (25 ppm) which is well below the range of drinking water standard (500 ppm) of the World Health Organization. This study has been conducted in Kajang, Malaysia during the month of August 2018 with an average daytime temperature of 32°C.