Performance enhancement of hemispherical distillers using copper chips and paraffin wax as energy storage integrated with an external condenser

Abstract

Three hemispherical solar still (HSS) models were compared in this study: a conventional (CHSS), one modified (MHSS) to use various types of heat storage materials, and the latter modified with an external condenser (MHSSC). In addition, three cases of different heat storage materials: (I) copper chips with reduced graphene oxide (rGO), (II) copper chips with (rGO) and paraffin wax as phase change material (PCM), and (III) copper chips with rGO and PCM involving copper chips were put to the test, and their results were compared with regard to system temperatures, hourly yield, daily production, thermal performance, and price per freshwater litre. Copper chips are combined with rGO and paraffin wax to augment the thermal properties of CHSS, and the external condenser was used to increase the freshwater through enhancing the condensation rate. The results demonstrated that case III showed the greatest improvement from both the freshwater output and thermo-economic viewpoints. Also, in this instance, for this case, with daily freshwater output and energy efficiency of 6.89 L/m2 and 66.82 %, respectively, MHSSC outperformed CHSS by 118.73 % and 118.22 %. Moreover, the diurnal exergy efficiency with the greatest value was 3.88 % for MHSS, which implies an improvement of 144.03 %. Finally, for MHSS and MHSSC, the cost for generating one litre of fresh water was 0.025 and 0.028 $/L, with freshwater cost reductions of 32.43 and 24.32 %, respectively.