Experimental Investigation on a Tubular Solar Still Using Custard Apple Seeds: A Sustainability Study

This study investigates the thermodynamic and water‐production performance of a conventional tubular solar still (CTSS) compared with a tubular solar still (TSS) utilizing custard apple seeds (TSS–CAS). The cumulative distillate yield of the TSS–CAS reached 3.60 kg/day, significantly surpassing the 2.76 kg/day obtained by the CTSS, an increase of 30.43%. The TSS–CAS energy and exergy efficiencies were 39.78% and 3.12%, respectively, compared with 26.56% and 1.45% for the CTSS, indicating improved efficiency in both metrics. From an exergy perspective, destruction within the evaporation basin peaked at 1:00 PM, reaching 586.11 W/m 2 for the CTSS and 527.20 W/m 2 for the TSS–CAS; exergy destruction within the glass cover reached its maximum values of 39.23 and 51.20 W/m 2 , respectively. The study revealed that exergy destruction in the saline water was lower in the TSS–CAS, peaking at 138.13 W/m 2 , compared with the CTSS, which peaked at 157.63 W/m 2 , thereby demonstrating improved thermodynamic efficiency. The integration of bio‐seeds into TSS enhances heat retention and minimizes exergy losses in the saline water. The economic, environmental, and enviro‐economic evaluations corroborated the TSS–CAS's increased yield and efficiency. The relative improvement in total carbon credit earned and total carbon emission mitigation for the TSS–CAS was 30.91% and 30.92%, respectively.