Performance Evaluation of a Double Slope Concrete Cascade Solar Stills

Abstract

The availability of drinking water is one of the major challenges faced by our modern society. There are certain locations where fresh drinking water is scarce, but brackish or saline water are available. The available water resources have been used to provide a clean, safe and reliable drinking water with metal basin solar stills using solar energy. The issue of rusting associated with the metal basin solar still constitutes a major problem. A concrete cascade double slope solar still was constructed and tested alongside a conventional metal basin solar still of the same dimensions. The performance tests compared the glass cover and basin water temperatures, as well as the yields of the two stills recorded at 30minutes interval, for seven days. The highest average daily glass temperatures for metal and concrete basin stills of 54.1 °C and 40.5 °C were recorded respectively for the metal basin and concrete cascade solar stills, at an average highest global solar radiation of 867.3W/m² and an ambient temperature of 35.1 °C. The highest average daily water temperatures of 58.3 °C and 51.1 °C occurred respectively for the metal basin and concrete cascade stills at the same time under the same atmospheric conditions. The average daily cumulative yields of the metal basin and concrete cascade solar stills were found to be 707.1 mL 577.4 mL respectively. The results show that the conventional metal basin solar still recorded a higher yield, but the concrete cascade solar still has overcome the rusting problem. There is, therefore, a compromise of 18.3% higher yield or a longer span working solar still without rusting.