Efficiency, productivity and economic analysis of polystyrene foam-insulated conventional and modified double-slope solar still using nanofluids.

This work presents the effect of adding copper oxide (CuO), aluminium oxide (Al₂O₃) and zinc oxide (ZnO) nanofluids towards distillate yield enhancement in the conventional and modified polystyrene foam-shielded single-basin double-slope solar still (DSSS). Nanoparticles are included to enhance the evaporative and thermal properties. Conventional and modified double-slope solar still of similar features were produced using aluminium sheets and an experimental analysis was performed in sunny days. Solar-activated vacuum fan and external condenser are incorporated in conventional DSSS and termed as modified DSSS. Integrating condenser and solar-actuated vacuum fan in the DSSS significantly reduces the heat loss attained due to convection. Results signify that using ZnO, Al₂O₃ and CuO nanofluids with 0.1% volume concentration in the traditional DSSS enhances cumulative productivity by 10.34%, 13.79% and 17.24% respectively. In modified double-slope solar still, the cumulative productivity enhances by 13.30%, 20.69% and 25.62% using ZnO, Al₂O₃ and CuO nanofluids. Using a condenser and vacuum fan without nanofluid in the modified DSSS improves the collective distillate yield by 40% as related to a conventional SS without nanoparticles. Combined effect of condenser with vacuum fan and ZnO, Al₂O₃ and CuO nanofluid with 0.10% volume concentration in the modified DSSS increases the collective distillate yield by 58.62%, 68.96% and 75.86% respectively compared to a traditional SS without nanofluid. Results signify that the peak energy efficiency of the conventional and modified solar still using ZnO, Al₂O₃ and CuO nanofluid increases by 12.81%, 17.70% and 23.03%, and 23.27%, 23.24% and 28.37%, respectively. Results also indicate that the peak energy efficiency in modified solar still using ZnO, Al₂O₃ and CuO nanofluid increases by 47.13%, 47.42% and 52.92% as compared to traditional solar still without nanofluids. Results signify that the maximum exergy efficiency of the conventional solar still using ZnO, Al₂O₃ and CuO nanofluid increases by 32.82%, 38.22% and 55.21%, respectively. In modified solar still, the maximum exergy efficiency enhances by 35.24%, 39.21% and 57.07% using ZnO, Al₂O₃ and CuO nanofluids, respectively. Among the various nanofluids, the CuO nanofluid attained the maximum CO₂ mitigated of 12.13 tonnes and 16.80 tonnes in both conventional and modified DSS. Among the various nanofluids, the CuO nanofluid attained the maximum carbon credits cost of $363.98 and $504.09 in both conventional and modified DSS.