Performance of a Rainwater Harvester and Double Slope Desalinator With Booster Mirror and Cooling Fan

Abstract

Abstract. Solar desalination is a promising method to utilize renewable energy for producing freshwater. This is done by utilizing a solar still to evaporate and condense impure water into potable water. However, traditional solar stills are less efficient. This study proposes a modified solar still design that incorporates cooling fans over the south-facing plexiglass, which are powered by a solar-charged battery, forming a fully standalone system. A rainwater collection tray is also integrated for its use during rainy days. The section of the tray facing south also acts as a booster mirror during bright sunlight. The system achieved a peak water temperature of 60 °C, with a yield of 0.95 kg/m2 h on October 12, 2024. Operating the cooling fans at their maximum duty cycle reduced the temperature of the south-facing plexiglass by approximately 10%, improving the condensation rate. The rainwater collection tray gathered 18.6 L on September 10, 2024, and 17.3 L on October 17, 2024. Under sunny conditions, the system recorded peak energy and exergy efficiencies of 34% and 3.38%, respectively. These dropped significantly during rainy days to an average of 8.14% and 0.27%, respectively. The fractional exergy of evaporation peaked at 0.69 on warmer days and fell to 0.6 on cooler days. Conversely, convection exergy declined from 0.125 to 0.07 as temperature increased. After desalination, water quality parameters improved, aligning with the findings of the existing literature on solar-distilled water.