Energy and exergy analysis of PCM-based pyramid solar still

Abstract

Sustainable and effective desalination technologies are required to meet the growing demand for drinkable water worldwide. The intermittent nature of solar desalination necessitates the use of efficient thermal energy storage materials (TESMs) to prolong operation past the hours of sunshine. To improve desalination performance, this study introduces a modified stepped pyramid solar still (SSP) that incorporates phase change materials (PCMs), hollow rectangular fins, and electrical heaters driven by photovoltaic energy. In comparison to a traditional solar still, the system was tested both conceptually and experimentally in five different configurations (CSS, SSP, SSP with electrical heaters (SSE), SSP with paraffin wax and hollow rectangular fins (SSM), and SSM with electrical heaters (SSME)) during the winter, spring, and summer seasons. The findings showed that, in comparison to the CSS, the productivity, energy, and exergy efficiency of SSP in the winter and spring increased on average by 109.47 % and 204.91 %, 28.44 % and 31.68 %, and 10.21 % and 18.15 %, respectively. While the productivity, energy and exergy efficiency of SSE3 was augmented over CSS on average by 266.62 %, 45.64 %, and 23.45 %, respectively. Furthermore, the productivity energy and exergy efficiency of SSM increased over CSS on average by 431.13 %, 70.67 % and 41.5 %, respectively. SSME obtained the highest performance, with an average increase in productivity of 675.2 %, energy efficiency of 78.77 %, and exergy efficiency of 48.97 %. To simulate saline water temperature fluctuations, a thorough heat balance study was carried out, and theoretical predictions and practical observations closely matched within acceptable error range between 0.76–18. The results demonstrate how PCM-enhanced solar stills can be used for high-efficiency, sustainable water desalination, providing a workable option for areas with low access to freshwater.