Further consideration of gas-particle mass transfer simulation during electrostatic precipitation using lower order representations of particle size distributions: Variable size distributions

A previous study identified the ratio of two characteristic time scales - hydrodynamic and electrostatic particle precipitation - as an indicator of whether gas-particle mass transfer during electrostatic precipitation could be modeled using a uniform particle size that represents the collective surface-to-volume ratio of the original polydisperse dispersion. The present investigation extends the earlier findings by examining the gas-particle mass transfer occurring during electrostatic precipitation of several log-normally distributed particle size distributions of varying mean particle diameters and geometric standard deviations. The results confirm that the ratio of hydrodynamic to electrostatic particle precipitation time scales can be used broadly for varying size distributions. The ratio can either be used to identify those conditions in which a lower-order representation of the particle size distribution can be used with little error, or outside of such conditions, to predict the relative error to be expected from substituting a computationally efficient uniform particle size in place of a fully resolved size distribution when predicting gas-particle mass transfer during electrostatic precipitation. In terms of computational time, using a uniform particle size results in more than an order of magnitude reduction in computational times using COMSOL (TM) Multiphysics. Such efficiencies could be attractive when iteratively designing processes for removing trace pollutants from combustion or for chemical and catalytic processes that rely on or are enhanced by manipulating particle suspensions.