3-d numerical simulation of particle concentration effect on a single-wire ESP performance for collecting poly-dispersed particles

In this paper a simple one stage wire-plate electrostatic precipitator is analyzed to predict particle transport and charging, and airflow patterns under the influence of EHD and external flows, assuming various particle concentrations. The investigated numerical model includes the governing equations describing the motion of ions, gas, solid particles and the effect of particle space charge. The complicated mutual interaction mechanisms between the three coexisting fields of gas flow, particle trajectories and electrostatic field, which affect an industrial ESP process, have been implemented using the User Defined Functions (UDFs) in commercial FLUENT 6.2 software. The electrostatic field and ionic space charge density due to corona discharge were computed by numerical solution of Poisson and current continuity equations using a hybrid Finite Element - Flux Corrected Transport method. The model takes into account the particle space charge density effect on the ionic charge density distribution. The airflow equations were solved inside FLUENT using the Finite Volume Method and the turbulence effect was included by using the k-ε model. The Lagrangian random walk approach was used to determine particle motion, as affected by EHD flows and turbulence effects. This part was performed with the aid of Discrete Phase Model (DPM) in FLUENT. The performance of the discussed ESP in the removal of particulates and the effect of different particle concentration on the gas flow pattern and corona discharge current was evaluated numerically assuming poly-dispersed particles with lognormal particle size distribution.