Experimental investigation of a stepped solar still employing a phase change material, a conical tank, and a solar dish

Abstract

The configuration of an external solar dish improves the performance of stepped slope solar still (SS) in an experimental setting. The use of an external solar dish raises the effects of the water basin, resulting in a higher rate of evaporation. The stepped still was designed, built, and tested in Ismailia, Egypt, using local weather conditions. The proposed SS had a 1 m2 base area and eight steps, a solar dish with a concentration ratio of 80, a cone tank, two centrifugal pumps, four photovoltaic modules totaling 1000 W, a control unit, and solenoid valves. The impact of utilizing the storage material during the phases was investigated. A nozzle was installed at the top of the cone tank. Four mass flow rates of circulated water were examined 250, 350, 450, and 550 mL/min. The control unit receives inputs from the photovoltaic output, photodiodes, and water temperature inside the cone. The control unit outputs the signal for the two solar dish motors, centrifugal pumps, and solenoid valves. First, a standard stepped SS, second, a stepped SS using phase change material (PCM), and finally, a stepped SS using PCM combined with a solar dish were investigated. The conventional stepped SSs with PCM had an optimal mass flow rate of 250 mL/min, whereas the stepped SS integrated with the solar dish had 550 mL/min of mass flow rate (an optimum value). The highest daily freshwater productivity was 7.63, 9.18, 11.23, and 13.9 kg/d for water spraying mass flow rates of 250, 350, 450, and 550 mL/min, respectively, with 0.0161 $/L/m2 of a maximum projected cost, according to data from an integrated stepped SS.