Enhanced solar still condensation by using a radiative cooling system and phase change material

Abstract

In this study, an experimental investigation of using the radiative cooling potential in a solar still was studied. Instead of using an auxiliary radiative panel, an integrated collector was utilized for both processes of absorption of solar radiations and emission of infrared radiations for radiative cooling. At night-time, the coldness was stored in the PCM inside the PCM-condenser. While during the day, the water was evaporated in an evaporation tank, the produced vapor was directed to the PCM-condenser and the air cooled-condenser. Different condenser configurations were tested to evaluate the effect of radiative cooling on daily yield and solar still efficiency. The lower temperature of PCM compared to the ambient air caused the condensation to start sooner. Therefore, the radiative cooling enhanced the condensation in the solar still and increased its daily yield by about 31.2%. The daily yield of the system was 2.139 kg/m2 without radiative cooling with an efficiency of 23.9%. Using the radiative cooling at night to store coldness in the PCM-condenser increased the daily yield and efficiency to 2.805 kg/m2 day and 30.7%, respectively. Because of the limited cooling capacity of radiative cooling, utilizing an air-condenser beside the PCM-condenser was necessary to condense all produced vapor.