Mathematical Study On A Direct Contact Humidifier of A Humidification-Dehumidification Desalination System

In a humidification-dehumidification (HDH) water desalination system, the humidifier is a significant component that directly impacts the overall process of producing fresh water from saline or brackish sources. In this study, a heat-mass transfer numerical model between the hot sprayed seawater and air on a direct contact humidifier was developed to investigate the effect of inlet seawater temperature, seawater mass flow rate, inlet air temperature, and air mass flow rate on humidifier effectiveness and freshwater evaporation rate. The results show that the optimum value of humidifier effectiveness is achieved on a unity mass flow rate ratio between seawater and air, and the seawater inlet temperature and the mass flow rate ratio between seawater and air are the most critical parameters influencing the productivity of the humidifier. The maximum value of water evaporation is 341 kg/hr that occurs at operating conditions of inlet seawater temperature of 90℃, inlet air temperature of 30℃, inlet air relative humidity of 50%, and seawater to air mass ratio of 5. The findings found that freshwater productivity improves by approximately 25% when the seawater temperature is increased by 10%.