Performance assessment of solar PV-driven hybrid HDH-RO desalination system integrated with energy recovery units and solar collectors: Theoretical approach

Recently, constructing a high productive desalination unit with low power consumption has been a challenge. Along with that, this study aimed to simulate a new hybrid desalination unit merging two common techniques of high freshwater production: humidification-dehumidification (HDH), and reverse osmosis (RO). For low power consumption, the hybrid HDH-RO unit was powered with a photovoltaic (PV) systems. The system was provided with thermal energy recovery (TER) units, double-pass solar air collectors (SACs), and evacuated tube solar water collectors (SWCs). The TER units were parallel connected to the backside of PV panels for dual function: enhancing the PV conversion performance by cooling and preheating the seawater before entering the SWC. Both SAC and SWC were proposed to improve the evaporation rate inside the humidifier of the HDH unit. For a comprehensive analysis of the HDH-RO system, five coupled theoretical models were derived and solved, which all were validated by previous experimental data from the literature. All results confirmed that the proposed system can be a good choice for producing freshwater with low power consumption. The maximum hourly freshwater production of the new hybrid HDH-RO desalination system varied between 192 and 200 L, with a water recovery ratio ranged between 48 and 49.8%. Also, its specific power consumption (SPC) ranged between 1.22 and 1.24 kWh/m³, with an average saving a range between 14.7 and 65% compared to previous techniques of RO desalination system.