Performance augmentation of spherical solar distiller using dual-axis sun tracking system with corrugated absorber and phase change material

Abstract

Abstract Freshwater scarcity is a growing global challenge, particularly in arid regions where sustainable solutions are urgently required. Solar distillation is a promising technology; however, its low productivity limits large-scale implementation. In this study, a novel integrated modified spherical solar still (MSPSS) is proposed, combining vertical absorber configuration, dual-axis solar tracking, optimized corrugated geometry, and silver nanoparticle-enhanced phase change material (PCM-Ag) to overcome the limitations of previously reported designs. The proposed system introduces a synergistic integration of optical, thermal, and geometric enhancements, enabling superior performance compared to conventional and previously developed spherical solar stills. Experimental results demonstrate a significant increase in freshwater productivity, reaching a maximum of 13,300 mL/m 2  day, corresponding to a 343% improvement over the conventional solar still (CSS). The individual contributions of the modifications include vertical absorber (62%), dual-axis tracking (65%), corrugated geometry (55%), and PCM-Ag integration (52%). In addition to productivity enhancement, the system improves thermal management by reducing temperature fluctuations and extending effective operating periods. Economic analysis reveals a reduction in freshwater production cost from $0.024/L for CSS to $0.01/L for the optimized configuration. These findings confirm that the proposed integrated approach represents a substantial advancement over existing spherical solar still systems, offering an efficient and economically viable solution for decentralized freshwater production in water-scarce regions.