Charging and Collection of Submicron Particles in Two-Stage Parallel-Plate Electrostatic Precipitators

A well-defined two-stage ESP experiment was carried out in the submicron particle size range. The experimental setup consisted of five components: a clean wind tunnel, a submicron particle generation system, an aerosol sampling and transport system, a submicron particle number concentration measurement system, and a pilot-scale two-stage parallel-plate ESP. Experimental collection efficiency data were obtained with a GMD of 0.03-0.2 μm and a GSD of about 1.67 for air velocities between 1.9 and 4.1 m/s under the nominal operation condition of two-stage ESP. The experimental data were then compared with the results of a numerical collection efficiency model which takes into consideration charging rate equations, particle equations of motion, and collection performance models. The comparison showed good agreement. It was confirmed from the comparison that the partial charging regime, where a portion of incoming particles is not charged, exists when the particle size range is below about 0.03 μm This partial charging effect causes a significant decrease in the ESP efficiency.