Heat and mass transfer in a direct contact humidifier of a humidification-dehumidification desalination system

A thermodynamic analysis of a direct contact humidifier in a Humidification-Dehumidification desalination system is presented. Applying mass and energy balances along the humidifier, a mathematical model was developed and a parametric study was carried out to study the effects of the inlet Temperature and mass flow rate of the seawater and air on the system performance. According to the obtained results, as the air mass flow rate increases, so the evaporation rate of the system does to a limit determined by the transversal area of the humidifier. In addition, increasing the sea water mass flow rate favors evaporation process because the temperature differences between the fluids gets bigger, however, increasing air mass flow represents a disadvantage in the energy consumption of the unit, so this is an important design parameter.