Effects of Serrated Pulsating Airflow on Liquid Film Evaporation in a Vertical Channel: A Numerical Study

Abstract

Effects of serrated pulsating airflow on liquid film evaporation in a falling film channel was numerically studied based on a two-dimensional model. The mechanism of pulsating airflow evaporation was studied as the pulsating airflow swept across the vertical liquid film surface at the stagnant temperature. Effects of amplitude, frequency, and velocity of the serrated pulsating airflow at certain evaporation time on evaporation were analyzed. Compared with the uniform airflow, the highest relative evaporation of liquid film on vertical pipe inner surface was increased by about 0.3 %. When the airflow was pulsating, the cycle of vapor mass flow rate was the same as the cycle of pulsating airflow. Pulsating airflow disturbed the boundary layer periodically and carried the vapor away; this intensified the mass transfer of liquid film, hence promoting vapor generation under certain conditions.