Passive heat transfer augmentation for productivity enhancement of tubular solar still: An experimental study

Abstract Tubular solar stills offer a simple and sustainable method for freshwater production; however, their productivity remains limited due to low heat absorption and insufficient thermal storage in the basin. Passive heat transfer augmentation techniques are well‐established for enhancing performance in various thermal applications. In the present study, their use in improving the productivity of a solar still is investigated. Four systems: a conventional TSS and three modified TSS units containing different metallic chips (iron, aluminum, and copper chips coated with carbon black powder mixed with black paint) were experimentally tested under identical outdoor conditions at a constant water depth of 1 cm. Temperature, solar irradiance, and distillate yield were recorded hourly, and thermal efficiency and daily productivity were evaluated. The experimental studies concluded that TSS‐copper chips showed better productivity with enhancements of 20.1%, 44.79%, and 87.2% compared to aluminum chips, iron chips, and CTSS, respectively. The thermal efficiency of TSS‐copper chips at 1 cm water depth is enhanced by 15.2%, 32.7%, and 57.9% over the TSS‐aluminum chips, TSS‐iron chips, and the CTSS, respectively. The cost of producing 1 L of freshwater is 0.0051, 0.0041, 0.0037, and 0.0033 $/L for the CTSS, TSS‐iron chips, TSS‐aluminum chips, and TSS‐copper chips, respectively. The study concludes that utilizing metallic chips as thermal energy storage materials is a viable approach for improving freshwater yield in solar desalination systems.