Comparison between double slope solar still and fourfold slope solar still: energy, exergy, exergoeconomic, and enviroeconomic evaluation

This paper proposes a single basin fourfold slope solar still, which includes a fourfold slope glass cover plate used for solar heat collection and steam condensation. In order to show the efficiency of the fourfold slope solar still, comparative experiments are conducted under the winter climate conditions in Hangzhou for testing the operational performance of a double slope type solar still (DOSS) and the fourfold slope still (FOSS), so as to make a comparative analysis between them. Results show that the productivity of the fourfold slope still is 19.51% higher than that of the double slope still, and the fourfold slope solar still enhances the average hourly energy efficiency by 31.11%. According to the energy method, the energy payback time values of the fourfold slope solar still and double slope solar still are 64.88 months and 75.42 months respectively. According to the environmental parameter method, FOSS and DOSS reduce 5.47 tons and 4.58 tons of CO2 respectively. The corresponding values based on the exergy environment parameters are 0.21 and 0.18 tons of CO2, respectively. The fourfold slope solar still has a more obvious emission reduction function than the double slope solar still. The cost of the distilled water of the fourfold slope solar still is 0.28 RMB/kg, and the cost of the double slope solar still is 0.30 RMB/kg. In addition, the environmental and economic parameters of the fourfold slope still and double slope still are 79.29$ (561.37RMB) and 66.35$ (469.76RMB), respectively. While, the corresponding values based on the exergoenvironmental parameter are 3.05$ (21.59RMB) and 2.56$ (18.12RMB), respectively. From the analysis of exergoeconomic and exergoenvironmental parameters, the fourfold slope single basin solar still appears to be more effective.