Performance improvement of double slope solar still via combinations of low cost materials integrated with glass cooling

Solar-driven desalination methods, particularly solar stills (SS), and their improvements have been widely paid attention. Along with that, the current work aimed to evaluate the augmented evaporation/condensation performance of a modified double slope solar still (MDSSS) compared to conventional solar still (CSS). For evaporation enhancement, three alternative combinations were applied in the still basin, which consisted of nanoparticles/fluid (carbon black/water), heat localization (wick), and sensible storage (gravel) materials. In other meaning, three cases were experimented; namely: MDSSS-I with gravel immersed in carbon black (CB) nanofluid, MDSSS-II with gravel atop thermal insulation and covered with black wick, and MDSSS-III with dispersed CB nanoparticles on the top of the second case combination. These modifications were suggested to enlarge the wet area subjected to solar radiation, increase thermal conductivity, and localize the heat on the water surface. On the other hand, for condensation improvement, passive water-based glass cooling technique was integrated with all cases to degrade the glass cover temperature. Besides the experimental investigation, thermo-economic assessment analysis of the system was performed via estimating energy and exergy efficiencies, and production cost. The results proved the aimed enhancements for all cases and the best performance was achieved from the MDSSS-III. In this case, the yield, average energy efficiency, and average exergy efficiency were improved by 68, 50.6, and 146.3%, respectively, compared to CSS. In addition, MDSSS-III attained highest cost saving by 30.7% compared to CSS as the cost per liter of freshwater productivity was 0.0147 $/L, and 0.0212 $/L, respectively. Hence, integrating such locally-available materials with DSSS may open a new sight for further enhancement and increase the opportunities for establishing large-scale practical plants.

Automated summary

The study focused on enhancing the performance of solar stills by using different material combinations, with significant improvements in evaporation and condensation efficiency. The best results were achieved by the modified double slope solar still (MDSSS) with dispersed carbon black nanoparticles on top, showing improved yield, energy efficiency, exergy efficiency, and cost savings compared to conventional solar stills.