Augmenting hemispherical solar still performance: A multifaceted approach with reflectors, external condenser, advanced wick materials, and nano-PCM integration

This study aims at improving the desalination process of hemispherical solar still (HSS). A modified HSS (MHSS) design was developed, incorporating a 35 cm radius hemispherical absorber to heighten vaporization area and sun exposure. The influence of various factors on the MHSS performance was evaluated: wick material (jute cloth vs. cotton wick), rear reflectors for concentrated solar radiation, fan integration for enhanced heat transfer, and a phase change material (PCM) with silver nanoparticles (Ag) positioned beneath the liner. The MHSS design itself achieved a 96 % gain in productivity over HSS. Jute cloth proved to be a more effective wick material than cotton. The MHSS equipped with external reflectors exhibited a significant 120 % improvement in productivity. Furthermore, fan integration within the MHSS resulted in a 172 % productivity increase (11150 mL/m²⋅day compared to 4100 mL/m²⋅day for the HSS). Besides, the enhancement (152 %) was observed with the MHSS incorporating both a fan and a PCM-Ag composite, yielding a total daily freshwater production of 10500 mL compared to 4150 mL for the HSS. These findings suggest that the MHSS design with optimized features, particularly the use of a fan and PCM-Ag composite, offers a promising approach to significantly improve solar desalination performance.