A new heat and mass transfer model was presented on the basis of Navier-Stokes equation. One-dimensional transformation was conducted on the function of liquid film flow in the process of falling-film

and the Grank-Nicholson Method was used to solve falling-film characteristics. The simulation result of theoretical model was validated with the experiment

and its error is within 17%. Heat and mass transfer coefficient formula was fitted based on the experimental data

and the biggest flow volume of liquid film was obtained in different diameters.