The efficiency of solar stills with copper-coated sponge cubes for water desalination: A comparative study

Water scarcity within the world may be an enormous threat to living beings. Potable water can be produced by renewable energy using solar desalination. In the quest for efficient water desalination methods, researchers have turned to solar stills as a promising solution. One approach to enhancing the productivity of solar stills is the utilization of copper-coated sponge cubes. These cubes, when integrated into the still, provide extended heating periods, leading to higher temperature differences. This, in turn, improves freshwater production by improving the performance of the modified still. In this work, three basin-type solar stills of each 0.5 m² area have been studied experimentally in the location of Coimbatore, Tamil Nadu. Comparative studies were done between the solar still modified with sponge materials and the modified solar still with sponges coated with copper powder. In these experimental studies, the various performance characteristics related to solar still efficiency have been examined. The sponges were placed inside the water of the basin. The commercially available copper powder was prepared like a paste and coated in the sponges, and it was increased in size to 0.005 m on all sides. The sponges pasted with copper powder reduce the energy losses from the still due to its high thermal conductivity and the evaporation rate also increased by the capillary action of the sponge. High heat transfer to water also occurred due to the addition of copper powder. From the comparative studies, the solar still with sponge materials coated with copper powder gives a higher yield. The proposed solar still with modifications improves efficiency. The solar still without modification gives a yield of 1.3 kg/day, the modified still with sponges gives an output of 1.5 kg/day and the modified still with copper-coated sponges gives an output of 2.35 kg/day. The copper-coated sponge cubes placed still produced an efficiency of 60.07%.