Enhancing solar still performance using external condensers and floating fins: A comparative study

Abstract

Solar distillation is a sustainable and cost-effective method for producing potable water from brackish sources. However, its widespread adoption is limited because of low daily freshwater yield and inefficient solar energy utilization due to slow evaporation and condensation processes. This study presents a series of modifications to enhance these processes: floating aluminum fins (FAF) to improve evaporation and two types of external condensers (single rectangular/REC and multiple cylindrical/MCEC) to optimize condensation. Four configurations were tested: Case I (conventional solar still/CSS), Case II (CSS + FAF), Case III (CSS modified with FAF + REC), and Case IV (CSS modified with FAF + MCEC). Key results demonstrate that Case IV (FAF + MCEC) achieved the highest performance, with an average daily yield of 2725 ml/day (80.36 % higher than CSS), peak instantaneous efficiency of 39.7 %, and exergy efficiency improvements of 163 % over CSS. Environmental analysis revealed that Case IV mitigated 420 kg of CO₂ emissions over its lifetime, earning $135 in carbon credits, offsetting its higher embodied emissions (1450 kg CO₂) from manufacturing. The system's payback period of 273 days and modular design highlight its economic and scalability potential for water-scarce regions. These findings underscore the viability of floating fins and multi-condenser designs to simultaneously address water scarcity, energy efficiency, and environmental sustainability.