Solar-Driven Desalination System Using Two Types of Evacuated Tube Collectors

Desalination is an appropriate response to climate change, increasing population, industrial activities, and drought. This study introduced a freshwater generation system using solar distillation via evacuated tube collectors (ETCs). Two geometries of evacuated tubes (Designs I and II) were used and the performance of the proposed system was evaluated regarding freshwater productivity, gained output ratio (GOR), and cost per liter (CPL). The difference between these tubes was the volume of the water circulating within them due to different internal geometry. No brine was produced and the system benefitted from zero liquid discharge technology. Maximum freshwater productivity values of 1145 and 1325 mL.h-1.m-2 were obtained for Designs (I) and (II), respectively. It occurred in June 2023 under a maximum solar radiation intensity of 1010 W.m-2. A maximum GOR of 0.71 and 0.82 was calculated at this peak solar radiation intensity for Designs (I) and (II), respectively. The quality of produced water met the standards of drinking water. The cost analysis led to the CPL of 0.0137 and 0.0132 US $ for Designs (I) and (II), respectively. The performance comparison of the proposed designs with other direct desalination units confirmed the superiority of these designs based on freshwater productivity, GOR, and CPL.