Performance enhancement of a passive solar still using mild steel scraps and copper powder

The conventional passive solar still is attractive since it is easily made and requires no electricity, however its productivity is typically limited by low basin water temperature and lack of continuous solar energy. This study evaluates the performance of a solar still modified by adding copper powder and mild steel scraps in the basin as thermal augmentation material. Copper powder was employed because it had high thermal conductivity, and mild steel scraps to increase heat storage capacity. All experiments used copper powder and mild steel scraps of 100, 250 and 300 g under the same operating conditions. A synergistic study of the 300 g copper powder and 300 g mild steel scraps combination was conducted. Basin water temperature, glass temperature, distillate yield, thermal efficiency and exergy efficiency were used to evaluate the modified configurations. An improvement over the conventional configuration was obtained from the combined copper mild steel configuration, with the highest distillate yield of 1.363 kg/day for a basin area of 0.5 m 2 . In the same configuration, the maximum thermal efficiency and exergy efficiency were 28% and 4.5% respectively. The results show that using a high thermal conductivity additive with a low-cost sensible heat storage material can increase evaporating water during the day, and heat stored during the sun’s weak days can be held in the tank. The proposed solution can achieve thermal performance improvement in the passive solar desalination system simply and inexpensively.