Influence of large seed particle on acoustic particle interaction dynamics: A numerical study

Abstract

Acoustic agglomeration as a promising preconditioning process for fine particle removal has been proven to be inefficient for submicron particles. In order to enhance the performance of acoustic agglomeration, large seed particles have been introduced into the flue gas. To understand the influence of seed particles on acoustic agglomeration, a nondimensional model of particle interaction was developed by taking into account all important particle interaction mechanisms. The simulated particle trajectories were validated against experimental data. The interaction dynamics of a seed particle and its neighboring fine particles was examined, and the dimensionless first collision time under different conditions was obtained. The results suggest that the enhancement of acoustic agglomeration with seed particle is mainly due to the acoustic wake effect. The overall collision kernel for the acoustic agglomeration was referred from the collision time. The results reveal that the dimensionless collision kernel almost increases linearly with the Stokes number of the seed particle, whereas its dependence on the Schmidt number of the fine particle varies significantly. The collision kernel for acoustic agglomeration was further compared with traditional collision kernels based on differential sedimentation, Brownian diffusion, laminar shear and turbulent shear. The results demonstrate that acoustic field indeed remarkably enhances the collision rate.