Numerical Investigation of Hemispherical Solar Still Performance With Optimal Amount of PCM as a Heat Storage

Solar stills are highly effective tools that assist the transformation of saline brine water into potable freshwater, thereby focusing on critical issues related to water scarcity and quality. The elaborate heat transfer process that occurs inside these stills is fundamentally driven by solar irradiance, which operates as a renewable energy source, allowing the efficient harnessing of thermal energy from the sun. To meaningfully improve the overall productivity and efficiency of these solar still devices, a pioneering enhancement in the evaporative mechanism is applied through the strategic incorporation of paraffin wax positioned beneath the surface of the basin, which functions as a thermal energy storage medium. In the present work, an analytical solution is done to study the performance of a hemispherical solar still with the addition of paraffin wax as phase change material (PCM), by the aid of COMSOL Multiphysics 6.2 software. Five values of PCM masses were used: 1, 5, 10, 20, and 30 kg. Results show that an increase occurs in both productivity and thermal efficiency. PCM case (1 kg) shows a better enhancement of 123% for thermal efficiency and productivity. The PCM addition was shown to increase the working hours of the still after sunset.