Performance of solar still units and enhancement techniques: A review investigation

Drinking water requirements are rapidly increasing while the availability of drinking water is decreasing. Overcoming this problem requires a sustainable energy source, such as solar energy, to desalinate untreated water. The most essential and simplest application of brackish water desalination is solar distillation. However, a limitation of the widespread use of solar distillation is its low yield. Therefore, several research attempts were made to enhance its productivity. Current work deals with a comprehensive review study on the solar distillation system. It presents the most critical factors and parameters affecting the productivity of solar stills and adjustments made to improve daily yield. Weather factors cannot be controlled but affect the performance of solar stills, such as solar radiation, ambient air temperature, and wind speed, while the operational and design parameters of solar stills can be manipulated, such as controlling the depth of the aquarium water and the thickness and angle of inclination of the glass cover. Improve evaporation and condensation mechanisms by increasing the basin water temperature and decreasing the distiller cover temperature, respectively, and tightening the thermal insulation to reduce heat loss to the surroundings. It was concluded that the productivity of solar stills may improve by increasing solar radiation and wind speed, as well as by decreasing the ambient air temperature. As for operational parameters, productivity improves as the depth of the water decreases and the thickness of the cover decreases. Designally, single-slope solar stills captured more solar radiation at both high and low-latitude stations than their double-slope solar still counterparts. Adding a packed layer to the basin's bottom or attaching a rotating shaft to the basin's surface can also enhance the solar distillation system. It has also been shown that the most effective design approach to improving the performance of solar stills is to use a slowly rotating drum inside the still, which can result in a 200-300 % increase in water production. The review will help researchers understand previous designs and develop a new set of characteristics to increase the solar still system's thermal efficacy and produce more distillate. Additionally, limitations are discussed along with suggestions for future research that might improve the productivity and performance of the basin solar still typical operating conditions.