Effect of air humidity at the entrance on heat and mass transfers in a humidifier intended for a desalination system

The aim of the present study is to investigate numerically the effect of inlet air humidity on an upward airflow in a humidifier intended for a humidification–dehumidification desalination system. A vertical parallel-plate channel constitutes the humidifier. One of the plates is wetted by a liquid water film and maintained at a constant temperature, while the other is dry and thermally insulated. The airflow enters the channel with constant temperature, humidity and velocity. The results show that the increase of air humidity at the channel entrance affects seriously the performances of the humidifier as it induces condensation of the water vapour on the walls. On the other hand, it was stated that the humidifier works well for low inlet humidity.