Solar still performance for small-scale and low-cost seawater desalination: Model-based and water enhancement

Water stress particularly affects developing regions. It is necessary to develop low-cost and small-scale solutions that do not require advanced technology and abundant energy resources to produce fresh water. A viable solution for rural coastal areas is seawater desalination using the solar still - a device that only relies on solar radiation to operate. The present work focuses on improving the solar still water yield. To achieve this objective, an alternative thermal model, which compromises a coupled energy balance for each solar still component, was proposed. This model increases the simulation accuracy for different designs, locations, and ambient conditions, predicting the water yield with a maximum deviation of 6% for the evaluated experiments. In addition, for a selected experiment, a parametric analysis was performed and, it was concluded that the potential parameters to enhance the water yield are: water depth, structure design, insulation, incident solar radiation, and basin-glass temperature difference. Based on the parametric study and the identified improvement solutions from the literature, feasible options were studied, such as: implementing reflectors, solar still design modification, increasing inner convection (insignificant improvement), using a porous medium (relevant for large water depths in the solar still) and separating evaporation/condensation (largely conditioned by ambient conditions).