Rotating-drum solar still with enhanced evaporation and condensation techniques: Comprehensive study

In this study, the thermal performance of the solar still was aimed to be improved in successive stages. This improvement was achieved via using a rotating drum inside the basin still to be nominated as drum distiller. The drum helps to increase the evaporative surface area and decrease the thickness of the saline water film. In the next stage of experimentations, a solar water heater was integrated into the drum distiller. After that, an external condenser was incorporated with drum still. Then, in the last stage of experiments, the effect of copper oxide nanoparticles on the performance of drum distiller was investigated. Different rotational speeds such as 0.02, 0.05, 0.1, 0.2, 0.5, 1.0, 2.0, 3.0, and 4.0 rpm were investigated. A theoretical model was built to predict the performance of the distillers under different conditions. An acceptable agreement was noticed between the experimental and theoretical values (7–13%). Results revealed that the maximum productivity was obtained at 0.1 rpm and using the condenser, heater, and nanofluid. Under these conditions, the freshwater productivity was 9220 L/m² for the drum still compared to 2050 L/m² for the conventional still with an enhancement percentage of 350%. Additionally, the estimated cost of 1 L of distillate for traditional and drum stills are about 0.05 and 0.039 $, respectively.