화학공학소재연구정보센터
Powder Technology, Vol.323, 393-402, 2018
A new multiple-time-step three-dimensional discrete element modeling of aerosol acoustic agglomeration
An acoustic agglomeration process, in which high-intensity sound is used to agglomerate particles in aerosols, can be simulated using the discrete element model (DEM). However, the conventional DEM is very timeconsuming due to the large difference between the various time scales involved in the modeling. In this paper, a multiple-time-step algorithm is used to speed up the 3D DEM simulation of aerosol acoustic agglomeration, which reduces the computational time by more than one order of magnitude, comparing with the conventional DEM. When the computational domain contains N particles, the computational complexity of the improved DEM simulation is of the order of O(N), by restricting the acoustic wake effect in certain ranges and performing contact detection based on a search grid. The DEM simulation model has been validated by: 1) the analytical solution for the oscillation motion of an isolated particle in a sound field, 2) the experimental result of the agglomeration trajectories of two particles under the mutual effect of acoustic wakes, and 3) the experimental results of acoustic agglomeration of coal-fired fly ash particles. It is found that the gglomeration efficiency obtained from DEM simulation is in good agreement with the experimental results at moderate sound pressure levels, while the simulation overestimates the agglomeration efficiency at a high sound pressure level of 149 dB, due to the breakage of aggregates in the experiment. (C) 2017 Elsevier B.V. All rights reserved.