The limit production of freshwater is considered the main problem of solar still. So, the objective of this work is studying the performance of single slope solar still coupled with phase change materials as a thermal storage unit and its effect on the still productivity. In view of this, different cases are considered namely, Case 1: solar still without phase change material (conventional solar still), Case 2: solar still coupled only with phase change material attached to the still base, Case 3: solar still with hollow cylindrical pin fins imbedded in the phase change material, case 4: solar still with phase change material and steel wool fibers in the still basin and case 5: solar still with only steel wool fibers in the still basin. The performance of the solar still for the five cases is experimentally evaluated and compared to each other's under the same climate conditions of New Borg El-Arab City, Egypt (Longitude/Latitude: E 029°42′/N 30°55′). The results revealed that the presence of phase change material negatively affects the daytime freshwater productivity with a significant increment in the overall freshwater yield of the still. Also, solar still with phase change material-based pin finned (Case 3) achieves the best thermal performance compared to conventional still (Case 1) and solar still with phase change material (Case 2). It is perceived that the total daily cumulative yield of distillated water of Case 3 is higher than those of case 1 and case 2 by 17 and 7%, respectively. Additionally, placing steel wool fibers in the basin accompanied with phase change material significantly enhances the daytime freshwater productivity with a considerable reduction in overnight productivity and an increase of the overall day productivity. Moreover, using steel wool fibers in the basin with a phase change material based solar still (case 4) enhances the total daytime freshwater productivity by 14% with a drop in the overnight productivity by 80%, compared to case 2. Among all tested configurations, case 5 achieves the highest accumulated daily freshwater productivity (approximately 25% an enhancement in the daily productivity compared to case 1) and thermal efficiency with minimum cost. |
