Performance enhancement of hemispherical solar stills using different shapes of basin liners (sinusoidal and half-circle) incorporated with inverted solar collectors

The current work aims to achieve the highest performance of hemispherical solar distillers, which are characterized by having a large condensation surface area. This requires increasing the evaporation rates inside the hemispherical stills by installing the sinusoidal and semi-circular linings in the hemispherical distiller basin to increase the heat transfer area between the basin water and the absorption surface. Also, these basin liners were incorporated with an inverted solar collector to speed up the evaporation process. To obtain the optimal basin liners that achieved the highest productivity, three hemispherical distillers were designed and fabricated, the first is traditional hemispherical solar still (THSS), the second is hemispherical solar still with a sinusoidal liner combined with an inverted solar collector (SHSS-ISC), and third is hemispherical solar still with a half-circle liner combined with an inverted solar collector (HCHSS-ISC). The results showed that compared with THSS (5.05 L/m²/day), the daily yield of modified distillers HCHSS-ISC and SHSS-ISC improved to 8.25 and 7.7 L/m²/day, with an improvement of 63.40 and 54.00%, respectively. Additionally, the daily efficiency of HCHSS-ISC, SHSS-ISC, and THSS reached 66.9, 62.45, and 41.20%, respectively. The economic feasibility indicated that using half-circle liners incorporated with an inverted solar collector reduced the cost of the distillate water produced from HCHSS-ISC by 30% compared to the THSS. These results showed that using half-circle liners incorporated with an inverted solar collector represents the optimal design that achieves the highest performance of hemispherical solar distillers with the lowest cost of producing distillate water.