Electrical Stimulation of Fabric Filtration

Abstract

With zero airflow, the currents passing between parallel wires in contact with a fabric appear to be the sum of corona currents and of non-ohmic conduction currents. The origins of the latter are not clear. Wheo an aerosol is flowing, electrode currents increase with increasing air velocity. Part of this effect seems due to charges carried on the aerosol particles, and part may be due to distortion of the ion cloud by the moving air stream. Pressure-drop reduction by external electric fields generated with wire electrodes occurs in two ranges: below corona voltages there is a small dependence on applied field, while above that voltage the dependence is much steeper. It is assumed that the latter case is the result of heavier particle-charging by the ion cloud. It seems, therefore, that corona-charging of the aerosol can play an important role in reducing pressure drop by ESFF. However, another mechanism appears to operate—one which becomes apparent if fabrics with different degrees of packing density are compared. Then, the pressure-drop dependence on applied field shifts with changing packing density in a manner, that suggests the onset of additional polarization effects.