Aerosol particle deposition in fibrous media with dendritic pattern, comparison between theory and experiment

When a suspension of fine, solid particles in a gaseous medium flows through a fibrous filter, particles deposit on the fibers forming chainlike agglomerates known as dendrites. This deposition pattern is responsible for the intrinsically transient behavior of the filter, leading to drastic increases of the filter efficiency and of the pressure drop. In the present work, an experimental technique is developed to study the deposition of monodisperse aerosol on a single fiber under well defined and controlled experimental conditions. The same area on the fiber surface is examined after each deposition run. The angular position of the individual dendrites, their size and configuration are recorded and photographed. Thus, the growth of several individual dendrites is followed with the time of deposition. The filter parameters for the experiment were chosen so that interception with inertial impaction are the main deposition mechanisms. Other deposition mechanisms like Brownian motion, electrostatic and gravitational mechanisms do not contribute significantly to the deposition rate. The data thus obtained are then used to test the validity of the model developed by Payatakes (1977). [...]