Exergo-economic analysis of a hybrid humidification dehumidification reverse osmosis (HDH-RO) system operating under different retrofits

The paper presents an exergo-economic analysis of humidification-dehumidification (HDH) desalination system operating under a conventional open-water open-air (OWOA) and a modified closed-water open-air (CWOA) configuration. Besides, the possibility of coupling a reverse osmosis (RO) system with HDH unit is also analyzed. The hybrid HDH-RO system is studied under three different retrofits including a simple HDH-RO, HDH-RO with a Pelton turbine and HDH-RO with a pressure exchanger. The analysis reveals that the modified cycle has a higher exergetic efficiency and lower product cost than the basic cycle. The product cost for the basic cycle with an electrical heater is calculated to be $6.56/m3 and with the solar heater $5.98/m3. Moreover, it is observed that the hybrid HDH-RO system with a pressure exchanger has the highest gained output ratio and second-law efficiency followed by HDH-RO with a Pelton turbine and simple HDH-RO, respectively. The product cost for hybrid HDH-RO with a pressure exchanger is calculated to be $0.13/m3 and $0.12/m3 with an electrical and solar heater, respectively.