DEM–CFD analysis of fluidization behavior of Geldart Group A particles using a dynamic adhesion force model

A discrete particle model for flows of Group A particles in Geldart's classification is studied. In general, Group A particles are fine and light, so that the adhesion force has a strong effect on their fluidization behavior. Inter-particle adhesion force of Group A particle was measured first. Secondly, the DEM–CFD coupling simulation with the measured adhesion force was performed, and the simulated results were compared with the experimental data about a small-scale fluidized bed for verification of the simulation. It was found from the results that there were considerable differences between their flow patterns. In order to reveal the cause of the differences, the effect of the adhesion force in the contact force model was studied on the motion of a single particle colliding with a wall. From the analysis on the particle–wall collision process, it is found that the spring constant used in the DEM model has a large effect on the particle's sticking behavior on the wall. The dynamic adhesion force model is proposed based on the present analytical investigation, and it is found that the present model well expresses the effects of the adhesion force on the flow structure for the case of a small adhesion effect. The effects of the spring constant kD on fluidization behavior is studied. This paper presents that the spring constant in the contact force model significantly affects the rebound and sticking behavior of particle's collision and proposes a novel dynamic adhesion force model that can express the effect of adhesive force on the fluidization behavior. [Display omitted] ► A coupled DEM-CFD simulation is performed for adhesive particles. ► The spring constant in DEM model significantly affects the fluidization behavior. ► The effect of adhesion force is enhanced with decreasing spring constant. ► A novel dynamic adhesion force model is proposed based on the theoretical analysis. ► The model can express the fluidization behavior using a reduced spring-constant.