Enhanced performance and theoretical parametric study on an activated stepped-type solar still compared to the conventional passive one

Abstract

To improve its performance, a modified stepped-type solar still (M-SSS) was implemented and setup with the same dimensions and specifications for conducting the performance comparison with the conventional one (C-SSS) through: installing external booster reflectors at top and bottom edges with the optimum inclined angles; integrating with a flat plate collector for preheating the inlet salty water; augmenting the still receiver with air cooling DC-fans powered by a PV solar panel for enhancing the evaporation and condensation rates. Thus, two SSSs were experimentally assessed at Faculty of Agriculture, Zagazig University, Zagazig, Sharkia Governorate, Egypt (Latitude 30.5^o – Longitude 31.5^o) under three different water salinity levels of 15000, 35000 and 45000 ppm under solar radiation insolation range of 490-998 W/m² and ambient temperature range of 31.8 to 36.5 ^oC. Additionally, a comparative parametric analysis was conducted on thermo-physical properties to describe the evaporative properties of the water that express to productivity and efficiency of both SSSs. The theoretical analyses are proved to be 62% of output production for the M-SSS higher than the C-SSS. The accumulative daily distillate output production of the M-SSS recorded 11.92 and 11.38, 10.92 and 4.48 to kg/m².day with an overall increase of 121.5, 133.0 and 143.3 % compared to the C-SSS for the previous salinity levels, respectively. Furthermore, the daily performance efficiency of the M-SSS was 56.3, 64.7 and 62%, meanwhile its annual cost of one kilogram of distillate water is decreased by 25, 39.8 and 42.5% for the same salinity levels, respectively. Thus, low cost and more performance improvements of stepped solar still for the represent modifications in this study is obtained. So, it could be recommended.