Enhancement of the solar still performance using bitumen, iron, copper and aluminum filings: Energy, exergy and economic analysis

This study experimentally investigates the performance of a solar still using bitumen combined with metallic filings, including iron, copper, aluminum, as well as black-painted aluminum coatings. The aim is to develop a low cost, thermally efficient desalination system by integrating six novel material configurations into a modified solar still (MSS), which is benchmarked against a conventional solar still (CSS). Both systems were fabricated with identical geometries and tested under natural conditions in Mansoura, Egypt from September to November 2022, with a fixed water depth of 4 cm. The MSS configurations included bitumen alone and bitumen mixed with iron or copper filings, with and without black painted aluminum coatings. Key performance parameters include temperature distribution, water productivity, energy and exergy efficiencies, and economic analysis. The best-performing configuration was bitumen with copper filings and aluminum coating, which achieved a daily productivity of 2.48 L/m2, representing a 76.16 % increase over the CSS. Thermal and exergy efficiencies enhanced from 21.2 % to 30.19 % and from 1.39 % to 2.42 %, respectively. The cost per liter dropped from $0.081 for CSS to $0.051 for MSS. The modified system can produce up to 841.5 L of distilled water annually compared to 477.7 L for the conventional system. The findings highlight the significant impact of thermal additives and coatings on improving solar still performance, offering a promising approach to low-cost freshwater production in arid regions.