Investigation of Tubular Solar Still with Watermelon Seeds Bio Waste as Thermal Storage Medium: An Economic Analysis

A study was conducted to assess the annual performance and energy efficiency of two types of Tubular Solar Stills (TSS) in the climate of Chennai, India. The first TSS yielded 569.7 kg of distilled water annually, while the second TSS, which incorporated watermelon seeds (WMS), produced 877.5 kg, marking a 35.08% increase. Additionally, the highest monthly energy efficiency observed for the TSS and TSS with WMS were 15.19% and 23.4%, respectively. On an annual basis, the CTSS achieved an energy efficiency of 13.3%, whereas the MTSS with WMS reached 20.49%. The payback period for CTSS and MTSS is 0.467 years and 0.312 years, respectively, achieving a 33.1906% decrease in MTSS in contrast to CTSS.