Performance improvement of thermal-driven membrane-based solar desalination systems using nanofluid in the feed stream

Different techniques have been proposed so far to improve the performance of thermal-driven membrane modules applied in solar desalination systems. These techniques have increased the freshwater productivity of the system but at the cost of its increased overall specific energy requirement. Due to this major drawback, the main objective of this study is to implement nanofluid in the feed stream of a heat pipe solar membrane-based desalination system, which not only aims to improve the freshwater productivity of the system, but also has the capability of decreasing its specific energy requirement. Synthetic seawater (with the salinity of 3.5%) was generated by dissolving appropriate amount of Sodium Chloride (NaCl) salt in normal tap water and used as the base fluid. Then, Aluminium oxide (Al2O3) nanoparticles were applied to fabricate the nanofluid. The performance of the system in terms of freshwater productivity, quality of treated water, specific thermal and electrical energy consumptions, gained output ratio, and overall efficiency was experimentally studied and compared under hot and cold climatic conditions of Perth in Australia. The results indicated that the application of nanofluid increased the freshwater productivity in hot and cold seasons by 18% and 22%, respectively. It also decreased the specific thermal energy consumption as this parameter was 17.5% and 14% lower in hot and cold seasons compared to the system without nanofluid. Moreover, using nanofluid improved the gained output ratio of the system by 9% and 18% under hot and cold climatic conditions, respectively. The overall efficiency of the system was also proved to be enhanced upon the application of nanofluid where the results showed 17.4% and 18% increase in hot and cold seasons, respectively.