Energy, Exergy, Economic, and Environmental Prospects of Solar Distiller with Three-Vertical Stages and Thermo-Storing Material

Solar distillation emerges as a viable remedy for addressing water scarcity in both remote and urban locales. However, its operational efficiency remains a limiting factor. Consequently, this study undertakes a comprehensive approach by introducing design modifications to enhance a distiller’s overall productivity. The pivotal adjustment involves configuring the distiller into a three-tiered structure, thus designating it as a multi-stage solar still (MSSS). Notably, the solar stills are crafted entirely from glass to optimize consistent solar tracking, eschewing the conventional sun-tracking rotation mechanism. Furthermore, the three-stage distiller undergoes refinement through the incorporation of a thermo-storing material (PCM) comprising paraffin infused with graphene nanocomposites at the base of the solar still (SS). Subsequent to these design enhancements, a comprehensive evaluation encompassing exergy, economic viability, environmental impact, and thermal considerations is conducted for both the conventional solar still (CSS) and MSSS. The outcomes elucidate that the upper stage of the MSSS outperforms its counterparts, producing superior results. Comparative analysis indicates a remarkable 160% enhancement in productivity for the MSSS over the CSS. Cumulative water productivities for the CSS and MSSS with PCM are recorded at 2840 and 7980 mL/m² during the daytime, reflecting an improvement of 181%. The energy efficiency metrics reveal values of 31%, 49.8%, and 53% for the CSS, MSSS, and MSSS with PCM, respectively. Moreover, the MSSS with PCM demonstrates an exergy efficiency of 5.8%. The environmental implications are quantified at 12 tons of CO₂ emissions per year for the MSSS with PCM. Finally, the cost considerations illustrate a reduction in the cost of freshwater for the MSSS with PCM (0.10 $/L) and the MSSS (0.13 $/L), as compared to the conventional SS (0.24 $/L).