Correlations between particle collection behaviors and electrohydrodynamics flow characteristics in electrostatic precipitators

Abstract

Electrostatic precipitators (ESPs) are widely used to eliminate particulate matter emissions from industrial sources. However, the complex electrohydrodynamics (EHD) flow in ESPs can cause controversial conclusions on particle collection. This paper established an ESP model with an additional source term added to the equation of gas momentum conservation. Correlations between particle motion behaviors and EHD flow characteristics were investigated regarding various discharge voltage, particle size, and electrode position. Results show that the EHD flow presented a back-and-forth distribution between the electrode and plate. The peak value of vy can be as high as 0.15 m s–1. The EHD flow can cause four possible types of particle motion status. The dominant factor for particle motion switched between the electric force and drag force along with the particle motion trajectory. There existed an escaping window at the ESP inlet. Particles released from this window penetrated through the ESP rather than be collected. Modifying the ESP geometry and increasing voltage can narrow the escaping window. When the ESP channel width was narrowed from 0.06 to 0.05 m, the maximum NEHD could increase by 73.4% from 0.94 to 1.63. Consequently, the collection efficiency was significantly improved. The collection efficiency can even amount to 100% for particles sized 2.5 µm.