Development and experimental analysis of an innovative self-cleaning low vacuum hemispherical floating solar still for low-cost desalination

Abstract

In this article, a novel floating salt rejecting solar still with a low vacuum condition on the evaporation chamber is developed and the performance is experimentally investigated. The new design adopts solar heat localization for interfacial evaporation and capillary water circulation to improve the evaporation rate and prevent the basin surface from residual salt accumulation. The basin is made in tubular structure composed of multi layers of porous foam and hydrophilic cellulose fabric for improved capillary water supply. The solar still consists of an external condensing coils coupled with the basin structure. It completely submerges into the water while the solar still is floating in the saline water reservoir (e.g. oceans). This enables the natural cooling of the condensing coils which increases the condensation rate. A low-cost hemispherical clear acrylic cover is used to capture the solar radiation from all directions on the basin. The system performance was examined under different scenarios. The system was found to generate distilled water at a daily rate of 4.3 L m−2 d−1 with the distillation efficiency of 35.6% during summer in Melbourne, Australia. The life cycle cost per litre of drinking water generated by the solar still is calculated at 4.7US ¢ L−1 which is substantially lower than conventional solar stills. This system is expected to have a lower maintenance cost as it does not require as much periodic cleaning. The new system developed is a feasible alternative to address the water security challenge for water-stressed communities at remote areas or disaster-stricken areas with no access to an energy infrastructure. Show more