Numerical study of effects of powder size and polydispersity on the dispersion of fine powders in a cyclonic flow

This paper investigated the dispersion of fine powder agglomerates in a cyclonic flow based on a combined computational fluid dynamics (CFD) and discrete element method (DEM) approach. Agglomerates formed with various particle sizes and polydispersities were dispersed at various airflow rates. The dispersion process was analysed in terms of flow and powder velocity, number of fragments and interactions on the agglomerates. It was observed that the dispersion was governed by two dominant but competitive interactions, i.e. particle-particle cohesion and particle-wall interaction. While the agglomerate of smaller particles is more difficult to disperse at a low flowrate with weak particlewall interaction, its dispersion is more efficient with increased flowrate and can generate larger fine particles than the agglomerate of larger particles. The effect of powder polydispersity is less significant to the dispersion efficiency, particular at a high airflow rate.