SO2 absorption and desorption by an accelerating water droplet undergoing vaporization

Heat and mass transfer between a water droplet and polluted air has been studied during the beginning of its free fall. Experimental results are compared with predicted ones from a model based on the Whitman film theory. The purpose of this article is to extend our previous model to predict the SO2 absorption and desorption by drops (1-5 mm) falling in air containing low gas concentration and including the natural droplet vaporization and cooling. The measured droplet temperature and sulfur concentration after small contact time (0.35-2.43 s) concords with model predictions. It is observed that the initial vaporization and its corresponding cooling effect increase the initial SO2 absorption rate and decrease the initial SO2 desorption rate