Effect of drag models on residence time distributions of particles in a wurster fluidized bed: A DEM-CFD study
Journal article, 2016

Fluidized bed coating has been used to coat pellets or tablets with functional substances for a number of purposes. In this coating process, particle wetting, drying and film formation are coupled to particle motion. It is therefore of interest to study particle motion in such fluidized beds and to use the results to develop a model for predicting the quality of the final product. In this paper, we present results from DEM-CFD simulations, i.e. discrete element method and computational fluid dynamics simulations of particle motion in a laboratory-scale Wurster fluidized bed that was also employed in positron emission particle tracking (PEPT) experiments. As the drag force is the dominant interaction between the gas flow and the particle motion in this type of fluidized bed, the effect of drag models on the particle motion is investigated. More specifically, the particle velocity and residence time distributions of particles in different regions calculated from five different drag models are presented. It is found that the Gidaspow and Tang drag models predict both particle cycle and residence times well. The HKL and Beetstra drag models somewhat overestimate the particle velocity in the Wurster tube and therefore predict a reduced number of recirculations and a significantly shorter cycle time.

Residence time distributions



Fluidized bed




Liang Li

Chalmers, Chemistry and Chemical Engineering, Chemical Technology

Johan Remmelgas

AstraZeneca AB

B. G. M. van Wachem

Imperial College London

Christian von Corswant

AstraZeneca AB

S. Folestad

AstraZeneca AB

M. Johansson

AstraZeneca AB

Anders Rasmuson

Chalmers, Chemistry and Chemical Engineering, Chemical Technology

KONA Powder and Particle Journal

0288-4534 (ISSN) 2187-5537 (eISSN)

Vol. 2016 33 264-277

Subject Categories

Physical Sciences



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