Electrical Stimulation of Fabric Filtration: Part II: Mechanism of Particle Capture and Trials with a Laboratory Baghouse

Calculations have been made of the efficiencies with which single fibers should capture aerosol particles when the fibers are placed in an electric field. A field oriented either parallel or perpendicular to the direction of aerosol flow should increase capture efficiency, but the perpendicular orientation should give a larger increase. These findings based on theory have been confirmed by bench-scale experiments using flat, nonwoven fabric filters. In addition, it has been found that the reduction in pressure drop that accompanies the application of electric fields is greater with the perpen dicular field. Experiments designed to find the optimum location for the electrodes with respect to the filter have shown that the greatest enhancement of performance is obtained when they are located just below the upstream surface of the fabric. Electrical stimulation of fabric filtration was further investigated using a one-hag lahoratory baghouse. With a commercial needled polyester fabric bag, a 4.5-kV potential applied between electrodes threaded into the bag fabric 15 mm apart and parallel to the bag axis reduced penetration about 50% and pressure drop about 45%. A pressure-drop reduction of this magnitude would effect significant reductions in energy consumption concomitant with the considerable increase in capture efficiency.