Numerical investigation of the separation mechanism in an electrostatic aerosol-to-hydrosol separator by glow corona discharge: a quantitative comparison of the effects of ionic wind and Coulomb force

Electrostatic separation of particles from air onto a liquid surface has attracted increasing attention for various applications such as wet electrostatic precipitators and bioaerosol samplers. In this study, the electrostatic separation of particles onto the liquid surface is numerically modeled in a simplified manner. The simulated separation efficiency is validated by experimental values reported in literature. The effects of ionic wind and Coulombic force on particle separation for various electrical mobilities, applied voltages, and air flow rates are studied by decomposing the total separation efficiency into two components: Coulombic and ionic-wind separation efficiencies. Both Coulombic and ionic-wind separation efficiencies show the same behaviors as the total separation efficiency with changes in the operating conditions: they increase with increasing applied voltage and particle electrical mobility, and with decreasing air flow rate. Overall, the ionic-wind separation efficiency is higher than the Coulombic separation efficiency, mainly because of the short residence time. However, when the applied voltage and particle electrical mobility are high, and the air flow rate is low, the Coulombic force outperforms the ionic wind. Time-scale analysis well explains the relations between the relative importance of each separation mechanism and the operating parameters.