Experimental study on the performance of pyramid solar still with novel convex and dish absorbers and wick materials

Abstract

Solar still is a famous technique of the desalination methods, but it suffers from the low productivity. In this paper, novel structured convex absorbers were proposed in a pyramid solar still. The performance of the pyramid solar still (PSS) was experimentally investigated when using a convex cylinder absorber shape (CCPSS) and dish shape of absorber (CDPSS) instead of the flat absorber. The proposed absorber shapes increased the surface areas of exposure and evaporation and reduced the water depth to minimum inside the distiller. Also, the experimentations were conducted when using different heights of convex dish shape (5, 10, 15, and 20 cm) to obtain the optimum convex height of the dish absorber. Besides, the system was experimentally investigated when using two different wick materials of cotton cloth and jute wicks that were put over the convex surface. Furthermore, the performance of CDPSS was tested when painting the absorber by black paint mixed with different nanocomposites of titanium oxide (TiO2) copper oxide (CuO) and silver (Ag). Systems performance based on economic, enviroeconomic, CO2 reduction, and energy point of view was studied. Experimental results revealed that the CDPSS provided better performance than either CCPSS or PSS. Also, the optimum height of dish absorber that obtained the best performance of CDPSS was 15 cm, where at this height (15 cm), the increase in productivity of CDPSS was 54% with jute cloth over that of the PSS. The highest productivity of CDPSS was obtained when using Ag followed by CuO and then TiO2, where the average daily productivity of CDPSS with jute and Ag was 6750 mL/m2.day compared to 3800 mL/m2.day for that of PSS (improvement = 78% and efficiency = 45.7%). Besides, the rate of CO2 mitigation for the CDPSS with Ag, CuO, TiO2 and without nanoparticles was about 13.5, 12.7, 12.5, 10.17 tons/y respectively. Also, the enviroeconomic parameter (Z^') was 147.6, 181.2, 184.1, and 195.1 per year for the (CDPSS), (CDPSS + TiO2), (CDPSS + CuO), and (CDPSS + Ag), respectively for 365 operating days and lifetime 20 years. Finally, the costs of the distilled water of PSS and CDPSS with jute cloth and silver nanoparticles were 0.018 and 0.015 $/L, respectively.