Boosting stepped solar still system efficiency with affordable natural energy absorbers

In this study, we examined a solar still made of galvanized iron that was exposed to a solar simulator with a light intensity of 904 W/m². We used iron ore, granite, and sponge as photoabsorbers on the surface of the stairs to enhance the interaction between air and water. This increased steam production and made the process of generating fresh water more cost-effective. We conducted experimental tests in different modes at three mass flow rates: 0.195, 0.134, and 0.1 kg/min.The results showed that increasing the mass flow rate of the inlet feed water decreased the production of drinking water and the evaporation efficiency in all three modes. Furthermore, iron ore effectively stored solar radiation energy, resulting in increased evaporation rates. The highest drinking water production was achieved using iron ore at a mass flow rate of 0.1 kg/min, with a value of 715 ml/min. In comparison, granite, sponge, and the base state had drinking water production values of 630, 555, and 515 ml/min, respectively. Economic analysis revealed that the lowest mass flow rate of the feed water led to the lowest product price when using iron ore (0.07$/liter), which is comparable to techniques reported in the literature.