Experimental study and mathematical model development for the effect of water depth on water production of a modified basin solar still

Freshwater is constantly shrinking with the confindness of water resources. Therefore, desalination of seawater is given great attention. Renewable energy sources also become of high importance to reduce carbon emissions. Thus, this study is concerned with the design, fabrication, and testing of a new single-slope double-basin solar still as a renewable energy-driven desalination system. It differs from the conventional solar stills by having two basins. The experiments were conducted to compare the performance of both conventional and modified solar stills. As a design parameter that substantially affects the performance, the still water depth was investigated. A new straightforward, accurate model is developed to predict both systems' performance for the design and optimization within a maximum deviation of ±6.6%. The results indicated that the day's productivity for the new and conventional stills at 2 cm water depth was 2.855 and 1.785 L/m² per day, respectively, by an increase of 59.9% with a thermal efficiency improvement of 61.3%. Also, a rise in the equivalent water depth de from 2 cm to 3 cm reduces the accumulated productivity by 14.36% and 15.41% for the SSDBSS and SSSS, respectively. Additionally, the daily thermal efficiency of the SSDBSS and SSSS is 25% and 15.5% for water depth de of 2 cm, respectively. The maximum values of the total heat transfer coefficient were also evaluated to be 15.4 and 55 W/m².ºC for the lower and upper basins of the modified system, respectively, and 30.18 W/m².ºC for the conventional system.