The Influences of Acoustic and Pulsed Corona Discharge Coupling Field on Agglomeration of Monodisperse Fine Particles

Abstract

In view of the low efficiency of traditional electrostatic precipitators in removing fine particles, acoustic and pulsed corona discharge coupling fields were proposed to increase particle size. In this paper, monodisperse particles with three different sizes (0.5 μm, 2 μm, and 4 μm) were generated to investigate the agglomeration effect under different parameters in external fields. A larger reduction ratio of particle number concentration resulted in a higher agglomeration efficiency. Results indicated that, in the range from 800 to 2400 Hz, the acoustic agglomeration effect on 4-μm particles was better than that on 0.5-μm and 2-μm particles. In the pulsed corona discharge field, agglomeration efficiencies of the three particle sizes were lower than those in the acoustic field. However, application of the coupling field highly improved agglomeration efficiency compared with the single field. When a pulse input voltage of 50 kV with acoustic sound pressure level (SPL) of 143 dB and frequency of 1600 Hz was selected, the corresponding number reduction ratio of 0.5-μm, 2-μm, and 4-μm particles increased to 0.464, 0.526, and 0.918 from 0.254, 0.438, and 0.814 in the acoustic wave field and 0.226, 0.385, and 0.794 in the pulsed corona discharge field.

Numerical Simulation and Analytical Evaluation of the Collection Efficiency of the Particles in a Gas by the Wire-Plate Electrostatic Precipitators

“…where u p represents the particle velocity (m/s), m p is the particle mass (kg), F represents the force acting on the particle (N), subscripts d, g, c, s, b, th, pg, and vm indicate drag, bouncy, Coulomb, Saffman lift, Brownian, thermophoretic, pressure-gradient, and virtual-mass forces, respectively. When a particle moves in a fluid environment, several forces, named as drag force Equation ( 9), bouncy force Equation (11), electrostatic body force (Coulomb force) Equation ( 12), Saffman lift force Equation ( 13), Brownian force Equation ( 14), thermophoretic force Equation ( 15), pressure-gradient force Equation ( 16), and virtual mass force Equation (17), may act on the particle. Detailed information about these forces can be found in the reference [29].…”

“…The applied voltage is the most critical parameter because it determines the electrostatic field and thus corona discharge [9,10]. The gas speed identifies the residence time of particles in the ESP and encompasses a direct impact on particle charging [9,11]. Inlet height, wire spacing.…”