Dust Deposition in Electrostatically Enhanced Fibrous Filters

A theoretical model to predict the total bed collection efficiency of a fibrous filter across which a strong electric field is applied is proposed. The fluid flow, as well as the electrostatic fields considered in the model, take into account the geometric configuration of the fibers in the filter. To predict filter efficiencies, dust-particle trajectory calculations are carried out to include inertial, interceptional, and electrostatic effects. Both the theoretical and experimental results demonstrate the dramatic increase in filtration efficiency by applying external electric fields to the filter at low Stokes numbers (St < 0.1). Experimental data were obtained by passing through the filter different pollutants such as latex aerosols (1-µm in diameter), DOP smoke, and two different kinds of solid dust generated by a specially constructed disperser. The influence of gas humidity on the separation process in the filter is also studied. The reported experimental data show good agreement with theoretical predictions, demonstrating that the physics governing the process have been properly incorporated into the model.