Thermodynamic analysis of solar-driven integrated system for efficient brine management and hydrogen production

This study presents a comprehensive system integrating solar energy through a photovoltaic thermal (PV/T) unit to generate electricity and thermal energy. This energy powers an ejector cooling system and supports reverse osmosis (RO) desalination. Rejected brine from the RO process is treated using reverse electrodialysis (RED) and the photo-chloralkali (PCA) process to produce valuable chemicals, including hydrogen, which is converted into electricity using a proton exchange membrane (PEM) fuel cell. A detailed thermodynamic assessment is conducted, including energy, entropy, and exergy balances, alongside a parametric study to evaluate system performance and optimize input parameters. The results show that the system achieved energy and exergy efficiencies of 66.9% and 23.1%, respectively, with the PV/T subsystem showing the highest exergy destruction rate. The system produces 18.78 kg/day of hydrogen and 120.6 m³/day of freshwater. The RED system generates hydrogen at 0.00041 kg/s where the production rate increases with rising current density while the PCA system produces hydrogen at a rate of 0.00024 kg/s. The PEM fuel cell generates 4.9 kW of electricity, though its efficiency decreases with higher current density.