Optimizing the performance of hemispheric solar still using nano-ZnO with cooling the glassy cover at a variable water flow rate

In this paper, a practical study is presented to improve the hemispheric solar still system by adding zinc oxide. Nanoparticles of various concentrations for 0.1, 0.2, and 0.3% with cooling the glassy cover with a variable flow rate of 1.5, 2.0, and 2.5 L/h. So, three hemispheric solar stills were built to study. The performance of a hemispheric solar still with nano-ZnO (HSS-Zn), and a hemispheric solar still with nano-ZnO with cooling the glassy cover (HSS-ZnC) are studied and compared with a conventional hemispheric solar still (CHSS) as a reference still. The results showed that integrating ZnO nanoparticles and cooling the glassy cover with hemispheric still enhances productivity. From tests, the daily accumulated productivity of HSS with ZnO nanoparticles (0.3%) and cooling the glassy cover with a flow (2.5 L/h) is 8.15 L/m²/day, which is 117.33% higher than CHSS. In that case, the daily efficiency of HSS with ZnO nanoparticles (0.3%) and cooling the glassy cover with a flow (2.5 L/h) and CHSS are approximately 74.57% and 79%, respectively.