Experimental investigation of a solar still with composite material heat storage: Energy, exergy and economic analysis

In the present paper, comparative study of solar still with internal reflector and composite black gravel-phase change material for thermal heat storage (THS) was presented experimentally. Two operating modes were prepared with different THS; composite material (SS-CM) and PCM (SS-PCM). The experimental model was tested in the climatic conditions of the Birkat Elsab City, Monufia, Egypt (Latitude of 30° 38′ 19.28″ N, Longitude of 31° 4′ 52″ E). The solar still economic feasibility, energy and exergy efficiency performance and water yield for the two operating modes were analyzed. The solar still water yield by utilizing the composite black gravel-phase change material is 3.27 L/m2 with augmentation by 37.55% rather than utilizing phase change material only with improvement in energy and exergy efficiency about 38% and 37% respectively. The water cost of 1 L produced from SS-CM was about 0.0014 US$/m2 with reduction about 27% less than SS-PCM. The composite heat storage material from paraffin wax and black gravel has a noticeable effect on SS productivity and performance.