Energy-Water Nexus: Renewable-Integrated Hybridized Desalination Systems

Humidification-Dehumidification Desalination

The humidification-dehumidification (HDH) method is principally the evaporation of water into a carrier gas and then vapor stripping of that carrier gas [53]. A simple HDH desalination is shown schematically in Fig. 13. This method has attracted the attention of desalination designers since 2006 because it has a lower operating temperature than other thermal distillation processes (< 80°C), and its operating pressure is near ambient air pressure [54]. In this approach, a carrier gas, usually air, is loaded with water vapor until it is saturated. The temperature of the humid air is then reduced, which dehumidifies the air, producing fresh water [55]. In the humidifier, air is saturated through interaction with hot seawater, which has been sprayed onto a tower to increase the contact area. The saturated air then passes over cooling coils, where dehumidification occurs. The main energy consumption for this method is through heating the saline seawater to produce vapor (for saturation of the carrier gas), making solar energy a good choice to couple with HDH systems [56].