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 (AlO) 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, AlO 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, AlO 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, AlO 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, AlO 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, AlO 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, AlO 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, AlO and CuO nanofluids, respectively. Among the various nanofluids, the CuO nanofluid attained the maximum CO 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.