Enhanced freshwater production in prism-type solar stills using a fresnel lens system with comprehensive energy-exergy and cost analysis

This study presents the development and performance evaluation of a novel prism-type solar still integrated with a Fresnel lens concentration system designed to concentrate solar radiation on an external spiral heat exchanger. Experimental investigations were conducted under two different saline water flow rates of 0.05 and 0.1 kg/min. The performance of system was comprehensively analyzed in terms of fresh water yield, thermal efficiency, exergy efficiency, and economic viability. The heated saline water and resultant vapor were directed into the prism-shaped condensation chamber, where condensation occurred efficiently. The experimental results demonstrated that lower saline water flow rates led to higher water temperatures and enhanced evaporation rates, thereby increasing freshwater productivity. In contrast, higher flow rates resulted in greater accumulation of saline water within the basin, reducing the evaporation rate and thus lowering overall productivity. The proposed design uniquely combines geometric enhancement via a prism-shaped condensation chamber with solar concentration through a Fresnel lens, enabling a dual-effect improvement in energy absorption and condensation efficiency, an approach not previously reported in the literature for solar desalination systems. The system achieved thermal and exergy efficiencies of 22.95 and 15.50%, respectively, at a saline water flow rate of 0.05 kg/min, producing 92 g of clean water in 60 min. Furthermore, the cost analysis conducted indicated a cost of $0.2546 per liter for this scenario.