Development of a Theoretical Framework for Particle Charging and Transport in Two-Stage ESPs and Unipolar Ionizers

HASAN AL TARIFY, Austin Andrews, Christopher J. Hogan, University of Minnesota

     Abstract Number: 107
     Working Group: Control and Mitigation Technology

Abstract
Electrostatic precipitators (ESPs) are aerosol control technologies that remove airborne particles by charging and capturing them through electrostatic forces. ESPs are commonly categorized into single-stage and two-stage configurations and have been widely investigated to assess their performance, especially in complex designs. While high-fidelity simulations can accurately model these systems by resolving the coupled multiphysics phenomena, including fluid flow, electric fields, ion transport, and particle charging, they are often computationally expensive, and are rarely used in the design of commercial ESPs. This study aims to develop a simplified model that captures the essential features of ESP operation without relying entirely on full-scale simulations. Specifically, we model the charging mechanisms by developing simplified approximations for the charging rate (nt product), assuming ballistic particle motion. This charging rate is then used to estimate the number of charges acquired by particles and then to predict collection efficiency with an analytical trajectory model. The predicted efficiency is compared with results obtained from full trajectory simulations. Our findings suggest that the nt product can be effectively estimated using an analytical expression for ion number density within the charging region, eliminating the need to solve for complete particle trajectories. Future work will focus on comparing the predicted charge fraction from ballistic motion against full trajectory results across a range of particle sizes and operating conditions to validate the model’s applicability further.