| Abstract: | A study of the enhancement of the collection efficiency of granular bed filters by electrical means is reported. By applying electric fields of a few kV/cm (DC or AC) across a bed of insulating granules, the efficiency for submicron charged aerosol is greatly increased, to the point where the efficiency minimum normally observed with such filters in the size range 0.1–1 μm is removed. The performance of such filters is explored as a function of granule size, applied field, face velocity and charge state of the entering aerosol with both a bench-scale flow system (to 40 ft3/min; 1.1 m3/min) and a wind tunnel (to 600 ft3/min; 17 m3/min). Some theoretical estimates are made to identify the most likely physical mechanism of electrical enhancement, and a number of potential application possibilities are discussed. |
