Enhancing freshwater production in solar distillation: Hemispherical absorber modification and reflectors integration

Solar distillers have been recognized as a potential solution to address water scarcity issues in both remote and urban areas. However, one of the challenges associated with solar distillers is their relatively low productivity. The objective of the study is to enhance the evaporation surface area and solar radiation exposure of the hemispherical distiller (HSS). So, the HSS was modified by installing hemispherical absorber inside it. The modified HSS was nominated by HAHSS. The study examines the impact of different absorber radii, specifically 35 cm, 30 cm, and 25 cm. Moreover, front and rear mirrors were employed to amplify the intensity of the radiation directed onto the hemispherical absorber, with particular emphasis on enhancing the radiation reaching the rear portion of the absorber. Also, the incorporation of PCM (Phase Change Material) combined with Ag (Silver) nanoparticles beneath the surface of the hemispherical surface, with a thickness of 2 cm. The results obtained that the distillate of the HAHSS and HSS was 8050 mL/m2.day and 4100 mL/m2.day, respectively. So, the HAHSS achieved a remarkable increase in productivity of approximately 96 % compared to the HSS. In addition, changing the absorber radius strongly affected the productivity rise of the HAHSS. So, using an absorber with a radius of 35 cm resulted in a distillate efficiency of 48.4 % and productivity rise of 96 %. While using an absorber with a radius of 25 cm was resulted in a distillate efficiency of 39.3 % and productivity rise of 36 %. Moreover, using reflectors increased the productivity of HAHSS by 160 % over that of HSS. Finally, the accumulated distillate for the HAHSS with reflectors and PCM + Ag and HSS was 11,400 and 4050 mL/m2.day, respectively with improvement percentage of approximately 181 % compared to the HSS.