Aspects of energy, exergy, economy, and environment for performance evaluation of modified spherical solar still with rotating ball and phase change material

Abstract

This study explores advancements in solar distillation, introducing a modified spherical solar still with a rotating ball to overcome traditional limitations of low productivity. The study conducted a comprehensive set of experiments in Kafrelsheikh, Egypt (31.1107° N, 30.9388° E) to compare the performance of the modified spherical distiller with that of the conventional spherical solar still. The evaluation encompassed various aspects, including energy, exergy, economic, and environmental dimensions. Key factors investigated within the study encompassed a range of rotation speeds (0.25, 0.5, 0.75, 1, 1.25, and 1.5 rpm), the introduction of a black jute wick material stretched over the rotating ball, and the utilization of a thermal storage material beneath the rotating ball. Two thermal storage materials were investigated with three arrangements (desert sand, copper grits, and mixture of both). The study's findings have unveiled that the optimal rotation speed for MSSS was 0.75 rpm, where the yield was augmented by 40 %. While incorporating wick material enhanced the distillate of the modified spherical distiller by 57 % when operating at 0.75 rpm. The best operating conditions for the modified spherical distiller were operating at 0.75 rpm and using wick and mixture of copper grits and desert sand, where the distillate reported 7160 ml/m2.day versus 3525 ml/m2.day for conventional spherical distiller, which means that the distillate was improved by 103 % and efficiency reached 59.5 %. Moreover, the exergy efficiencies for the conventional and modified spherical distillers at 0.75 rpm with thermal storage material, are 3.1 % and 4.2 %, respectively. Also, the cost of producing one liter of distilled water for conventional spherical distiller, modified spherical distiller, and modified spherical distiller with thermal storage material was determined to be $0.066, $0.043, and $0.024, respectively. Finally, the environmental parameter for modified spherical distiller with thermal storage material amounted to 27.7 tons of CO2 annually. Furthermore, the enviroeconomic parameter (Z') for the conventional spherical distiller and modified spherical distiller with thermal storage material stood at 335 and 365 per year, respectively.