Performance enhancement of a double slope solar still with rotating metal-wick structures: An experimental approach

Water is the most vital natural resource. Unlike saline water, fresh water is suitable for direct consumption, agriculture, and industrial uses. Solar stills utilize abundant solar energy for water desalination, present eco-friendly solution for converting saline water to fresh water. However, their widespread implementation is constrained by low distillate yield and efficiency. This study experimentally investigates the performance of solar stills through integration of rotating metallic cylinders and petals along with fabric and yarn as wick materials. Novelty in the study includes petal shaped design of rotating member in the still, adoption of yarn wicks, and use of metal meshes. Wick characterization and humidity tests were conducted to evaluate water absorption and evaporation potential of different wick materials. Refinements, namely, external reflectors, glass cooling, and external condenser, were explored to enhance the system performance. Among the tested configurations, the solar still utilising rotating mesh petals with jute yarn exhibited the highest daily yield and thermal efficiency of 3058 mL/m2 and 47.4% an improvement of 164% and 169%, respectively, over the still without a rotating member. System refinements further elevated productivity to 4056 mL/m2 with thermal efficiency of 57% and exergy efficiency of 2.55%. The distillate exhibited a total dissolved solids concentration of 19 ppm, ensuring exceptional purity. Economic analysis indicated that inclusion of external reflectors resulted in most cost-effective operation, with distillate cost of 0.097 $/L and payback period of 710 days. Environmental impact assessment revealed significant carbon mitigation potential of 8.8 tons, reinforcing the sustainability of present system.