Numerical investigation of heat and mass transfer characteristics within narrow channel in a packing humidifier

A numerical investigation of air/water direct contact heat and mass transfer process, by means of the volume of fluid method in a packing humidifier, with a new two-dimensional model, is used to conduct the flow characteristic of falling film. Unlike previous models for humidifiers, penetration mass transfer theory is employed to predict the field of mass fraction of water vapor accurately. Meanwhile, the influences of water temperature, inlet air velocity, as well as the water vapor concentration in the air and structure parameters, on the heat and mass transfer process have been studied. It is found that the mass fraction of water vapor increases with the increase in the inlet water temperature and inlet air humidity, but decreases with the increase in the inlet air velocity. When the inlet air velocity increases from 0.5 to 2 m s(-1), the mass fraction of water vapor decreases from 0.029 to 0.019 kg kg(-1) (or -34.48%), resulting in the decrease in the average mass fraction of water vapor from 0.0375 to 0.026 kg kg(-1) (or -30.66%). The effects of inlet water temperature, inlet air humidity, and inlet air velocity under designed parameters are quantitatively assessed, which provide useful insight into the optimization and design of humidifier.