Energy, Exergy, and Economic analysis of low thermal conductivity basin solar still integrated with Phase Change Material for energy storage

Abstract

Latent heat energy storage material has been used by many researchers to achieve an enhancement in the yield of solar still. However, the poor thermal conductivity of Phase Change Materials (PCM) used in solar still led to slower charge/discharge of the energy stored in it. This led to the dissipation of most of the energy stored in the PCM as losses happening in the solar still instead of getting converted into useful work. In this study an attempt was made to improve the yield of the solar still incorporated with PCM by using a low thermal conductivity material to construct the basin of the still, thereby reducing the heat loss occurring along the bottom surface and sidewalls of the still. In the present study, the basin of the conventional solar still (CSS) used for experimentation was made of galvanized iron, which was used as a reference still. The other two stills were incorporated with PCM, whose phase change temperature ranges from 58.03 °C - 64.5 °C. Among the stills incorporated with PCM, the basin of one of the still was constructed using galvanized iron (GIBSS) while the basin of the other still was made using acrylic (ABSS). From the experimentation, it was inferred that the usage of acrylic as basin material helped to reduce the charging span of the PCM but also delayed the discharge time of the PCM, thereby enhancing the yield of the still. The yield of ABSS was 4.36 L/m2/day, which was 10.1% and 19.1% higher than GIBSS and CSS respectively. Meanwhile, the exergy efficiency of ABSS was 3.46% and that of CSS and GIBSS were 3.56% and 2.99% respectively. The cost per liter of water produced by CSS, GIBSS, and ABSS was found to be ₹0.67, ₹1.09, and ₹1.23 respectively.