Clean Water Harvesting in Challenging Terrains: Evaluating a Novel Pyramid Solar Still Design with Evacuated Tube Integration

Solar distillation is a viable method for transforming salty water into potable drinking water, especially advantageous in rural regions with restricted access to clean water. This research presents an innovative pyramid-shaped solar still with a basin size of 0.836 m<sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup>, aimed at improving output. The system has evacuated tubes directly connected to the basin’s bottom side, complemented with black stones inside the basin to enhance heat absorption. The experimental configuration was refined for the geographical coordinates of Bandarban, Bangladesh (Latitude: 22°11’41.8"N, Longitude: 92°13’12.6"E). Performance assessments were performed under three operating conditions: (1) the solar still alone, (2) the Evacuated Tube Collector (ETC) independently, and (3) the solar still in conjunction with the ETC. The findings indicated a peak daily distilled water production of 2 liters from the still alone, which rose to 3.9 liters when integrated with the evacuated tubes, demonstrating a 95% increase in output. Thermal efficiency was assessed, revealing values of 18.61% for the standalone still, 20% for the standalone ETC, and 21.95% for the integrated system. Moreover, the water quality examination revealed a substantial decrease in salt (CaCO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf>) concentration, decreasing from 391.93 ppm to 5.11 ppm, thus validating the system’s efficacy in delivering potable water. The results underscore the possibility of integrating solar stills with evacuated tube collectors to enhance distillation efficiency and yield.