Performance enhancement of solar desalination using evacuated tubes, ultrasonic atomizers, and cobalt oxide nanofluid integrated with cover cooling

The water shortage crisis has been paid attention to and many efforts have been conducted to find proper and applicable solutions to it through developing desalination systems. Commonly, being simple in construction and easy operation, solar stills (SSs) have been developed to meet the freshwater need; especially, in arid areas. However, their productivity and efficiency improvement are still a challenge. Accordingly, the current work aimed to enhance the thermo-economic performance of a pyramid SS (PSS) by augmenting the evaporation and condensation processes. For obtaining high vapor generation, evacuated tubes and ultrasonic foggers were integrated into the developed PSS (DPSS) as a first case (DPSS-I), in which different operation times of the foggers were tested. Then, Co₃O₄ nanofluid (1.5 wt%) was added as a basin fluid in the second case (DPSS-II). Finally, in the third case (DPSS-III), a glass cooling was used for boosting the condensation rate. Besides the experiments, a complete thermo-economic performance analysis was done via calculating the energetic and exergetic efficiencies and freshwater cost (per liter). All these performance indicators of DPSS were compared to that of traditional PSS (TPSS). As resulted, integrating all the proposed additives (DPSS-III) could enhance freshwater production, energy efficiency, and exergy efficiency by 83.87%, 18.29% and 38.86%, respectively. Additionally, the production cost, per freshwater liter, was reduced by 11.61%. These results showed the applicability, sustainability, and feasibility of the proposed additives in the field of solar desalination, particularly SSs.