Increasing the production of fresh water in a stepped solar still by different natural materials as photoabsorber

Abstract

Abstract In this paper, a stepped solar still made of galvanized iron, exposed to a solar simulator at a light intensity of 904 W/m2, was experimentally studied. Iron ore, granite, and sponge as photoabsorber were utilized on the surface of the stairs to increase the evaporation efficiency and drinking water production. In each mode, experimental tests were conducted at three mass flow rates, including 0.195, 0.134, and 0.1 kg/min. The results showed that increasing the mass flow rate of the inlet feed water results in reducing the drinking water production and the evaporation efficiency in all three modes. In addition, the iron ore is able to save solar radiation energy inside itself well, and consequently the evaporation rate increases. The maximum drinking water production archived by using iron ore at a mass flow rate of 0.1 kg/min with an amount 715 ml/min. However, the corresponding value for granite, sponge, and base state was recorded 630, 555, and 515 ml/min, respectively. Also economic analysis showed that the lowest mass flow rate of feed water leads to the lowest price of the product via using iron ore (0.07 $/lit) which is comparable to reported techniques in the literature.