On the Energy Performance of the Geothermal Dehumidifier of the Humidification-Dehumidification Desalination System

The solar-driven humidification-dehumidification desalination system with a geothermal dehumidifier (SD-HDH-GD) has been given special attention, especially for subsurface irrigation. This contribution scrutinizes the performance of the geothermal dehumidifier of the SD-HDH-GD system. To this aim, a comprehensive three-dimensional transient computational fluid dynamics model of the geothermal dehumidifier and the surrounding soil is developed. An experimental setup is established to verify the developed numerical model. The effect of several operating parameters on the performance of the system is examined. The sensitivity of the water yield, recovery ratio, and gain output ratio to the studied parameters are analyzed. It is demonstrated that the system has different behaviors regarding these measures. Therefore, to gain a comprehensive understanding of the performance of the SD-HDH-GD system, all measures should be considered. According to the obtained results, the maximum amount of condensed water, gain output ratio, and recovery ratio obtained using the performed optimization are 180.05 kg/12 h, 41.20%, and 0.31, respectively, for the open-air HDH cycle. Moreover, to reach the optimum system performance, the temperature of the inlet air stream to the geothermal dehumidifier should be in the range of 60-70 degrees C, and its relative humidity must be as much as possible.