Characteristics of surface electric potential of filter medias in hybrid electrostatic filtration system

For improving the hybrid electrostatic filtration systems, we investigated the distribution and decay of electric potential on the surface of filter media after corona charge treatment in a needle-plate system. Firstly the dielectric filter media were charged in the needle-plate system. After the corona discharge ended, we measured the surface potential of the filter media with voltmeter to obtain the distribution and the decay feature. The tested filters included two clean ones, namely PE (polyester) and Bag filters, and a dirty one, particle-contaminated PE. The experimental results show that, the surface electric potentials of PE and Bag filters distribute relatively uniformly with their relative deviations below 15%, and trend to be stable after the two filters being exposed to air for 45 s and 15 s, respectively. That is to say, the surface electric potential decays faster in Bag than in PE. Increasing the corona discharge voltage from 12 kV to 35 kV, the initial surface electric potentials on the clean filters change barely, which are 1500 V for PE and 1200 V for Bag. Meanwhile, for the dirty PE, the surface electric potential is low at the particle-comprised cake layer but high on the clean media. The results can be used as a reference for designing hybrid electric filtration systems.