A review of the use of phase change materials on performance of solar stills

Abstract

• The paraffin wax offers the highest enhancement in productivity, energy and exergy efficiency. • Paraffin wax emerges as the most excellent phase change material for solar stills. • The hollow cylindrical pin fins are excellent to increase the thermal conductivity of paraffin wax. • The copper oxide nanoparticles are most appropriate nanoparticles to mix with paraffin wax. To convert the brackish water into potable water economically solar still can be used. It was reported that the main cause of its inferior performance is the heat loss from the solar still. To increase the yield of a solar still, the dissipated heat is stored in phase change material and reused during evening and night time for distillation. This paper reviews the state of the art of solar stills built-in with phase change material to investigate the best phase change material for solar still. During the review of reported works, it is observed that the paraffin wax amongst lauric acid, bitumen, stearic acid, palmitic acid, capric acid, beeswax and myristic acid is the most excellent phase change material for passive as well as active solar still. The paraffin wax increases the productivity, energy and exergy efficiency of a single basin passive solar still by 180%, 67.20%, and 40% respectively. The productivity augmentation for active solar still with paraffin wax is found as 307.54%. Paraffin wax has low thermal conductivity, hence, the hollow cylindrical pin fins on the absorber plate within the paraffin wax is emerged as the best technique to increase its thermal conductivity. This arrangement increases the productivity and energy efficiency of a single basin passive solar still by 11.96% and 37.50% respectively. Thermal conductivity can also be increased by mixing nanoparticles with PCM. The copper oxide nanoparticles are found as the most appropriate nanoparticles to mix with paraffin wax since this blend increases productivity by 125%.