Efficiency of a Dielectric Fibrous Filter Under Unipolar Particle Charging: Effects of Surface Potential and Grounding Probe Configuration

Abstract

The problem of indoor air purification is becoming increasingly relevant every year. Among devices, filters based on dielectric fibers stand out, which capture precharged aerosol particles in the filtered air flow. In this study, we demonstrate the influence of the configuration of the grounding electrode located in the filter for removing excess charge to ensure safe filter operation on the filter efficiency in capturing NiO aerosol particles. This study proposes a method for measuring the total charge and local potential of dielectric polypropylene fiber filters. It has been shown that placing the grounding electrode closer to the outer surface results in significant potential non-uniformity, with the potentials between the electrode turns being approximately three times higher than those above the turns. This disparity directs charged particles toward low-potential zones, reducing overall efficiency. Conversely, shortening the electrode and embedding it deeper promotes uniform surface potential and maximizes total charge, which provide the lowest penetration rates for NiO particles (0.23 and 0.14%). Additionally, a proposed model of the filter electrical properties, in which each filter section is considered as a resistor, explains charge and current distribution. Finally, we discuss capture mechanisms and the contribution of each to the overall filter efficiency.