Abstract
In this study, new rotating discs solar still (SS) has been investigated with different discs' configurations, thermal energy storage unit (TESU) and employing external reflectors. Three shapes of rotating discs (flat, finned and corrugated) have been studied at constant rotational speed of 0.1 rpm. Four rotating discs are used on the back and side walls of the discs SS to increase the evaporation surface area of water and the exposed area to solar energy. The results showed that finned discs are the best for SS performance when compared with flat and corrugated discs. The improvement in productivity is 68%, 86% and 106% over the conventional SS for flat, corrugated and finned discs SS (FDSS), respectively. When employing TESU (Paraffin wax mixed with CuO nanoparticles) with emerging fins, the FDSS productivity showed 149% increase in productivity over the conventional SS. For further enhancement in FDSS productivity, external reflectors are utilized, where the productivity of FDSS with TESU and reflectors showed 184% productivity rise over the conventional SS. The thermal efficiency of the flat discs SS, corrugated discs SS, FDSS, FDSS-TESU and FDSS-TESU-reflectors is 44.5, 47, 50, 56.5 and 51.3%, respectively. The estimated costs per liter of produced freshwater from conventional SS and FDSS-TESU-reflectors are 0.024 and 0.014 $, respectively.