Innovative integration of corrugated absorbers, PCM, and reflectors for enhanced water yield in solar distillation: A comprehensive 4E analysis

Abstract

Freshwater scarcity remains a major challenge in arid and remote regions, where conventional desalination is either expensive or energy-intensive. Solar distillation is a sustainable alternative, though its productivity is often limited by insufficient heat absorption and thermal losses. In this study, a hemispherical solar still was enhanced by integrating three key modifications: a corrugated absorber to increase heat transfer surface area, phase change material (PCM) to store and release heat during off-sunshine hours, and external reflectors to redirect additional sunlight toward the basin. Three still configurations were experimentally evaluated under identical climatic conditions in El Oued, Algeria: a reference hemispherical still, a still with a corrugated absorber, and a still with the combined corrugated absorber, PCM, and external reflectors. The daily freshwater yield increased from 4.50 L/m2 for the reference still to 6.70 L/m2 (48.9% improvement) with the corrugated absorber, and to 8.60 L/m2 (91.1% improvement) when PCM and reflectors were also included. Energy efficiency improved from 39.14% to 58.16% and 74.51% for the same systems, while exergy efficiency increased from 0.07% to 0.22% and 0.31%, respectively. The cost of freshwater decreased to $0.006 per litre for the fully enhanced design, with the shortest payback period of 23 days. These results demonstrate that combining absorber surface enhancement, thermal energy storage, and solar concentration significantly improves productivity, efficiency, and economic viability of hemispherical solar distillers. The novelty of this work lies in the combined integration of surface-area enhancement, thermal storage, and solar radiation concentration in a hemispherical still, experimentally demonstrated under identical conditions and assessed through a comprehensive 4E evaluation.