Performance assessment of an innovative multi-enhanced tubular solar still using local materials: 4E evaluation

Freshwater scarcity is a critical global issue, especially in arid and remote regions where access to clean water is limited. Solar distillation offers a sustainable and environmentally friendly approach by utilizing abundant solar energy for freshwater production. However, conventional systems are often hindered by low thermal efficiency and limited water output, restricting their practical applicability. This study presents a novel enhancement of the tubular solar still through the integration of a heat pump, solar dish collector, cover cooling system, and reflective mirror. These modifications aim to improve thermal performance, water productivity, and economic viability. A conventional tubular solar still (CTSS) was used as a baseline, and the improved TSS was experimentally tested under three configurations: Case 1 included a dish collector and heat pump; Case 2 added cover cooling; and Case 3 incorporated all enhancements, including a reflective mirror. Results demonstrated significant improvements: water productivity increased from 3.17 L/m²/day (CTSS) to 16.82 L/m²/day (Case 3); thermal efficiency rose from 30.91 % to 75.02 %; and exergy efficiency improved from 1.71 % to 6.19 %. These gains represent enhancement ratios of 143 % and 220 %, respectively. Additionally, freshwater cost decreased from $0.0224/L to $0.0179/L, while CO₂ emission savings increased from 0.91 to 6.30 tons annually. This work introduces a scalable, cost-effective solution that advances solar distillation performance beyond previous efforts in the literature.