Effect of water depth in productivity enhancement of fouling-free non-contact nanostructure desalination system

Abstract

Water scarcity is a major global challenge that requires utmost attention. Solar desalination could be one of the possible solutions to this problem. In this work, a non-contact nanostructure (NCNS) has been designed and developed that is physically and thermally decoupled from the water inside the solar still. The NCNS first absorbs the thermal radiation and then transfers its absorbed energy to water via infrared radiation, developing a contactless mode of heat transfer. The optical characterization for the absorber and emitter surface was done using state-of-the-art ultraviolet–visible-near-infrared (UV–vis-NIR), Agilent Cary 5000 spectrophotometer, and 410-Vis-IR portable emissometer and solar reflectometer. The absorptivity of the nanocoated absorber top surface was 90 %, while the emissivity of the emissive bottom surface was 85 %. Experiments were performed using synthetic saline water for six days without and with reflector at different water depths such as 0.5 cm, 1 cm, and 1.5 cm, respectively. The increase in water depth did not show a significant enhancement in productivity due to the interfacial heating effect of the NCNS. Analytical modeling, fouling study, accelerated corrosion study, and water quality assessment were also performed, and the results were so promising that the freshwater obtained was safe for drinking.