DEM investigations of fluidized beds in the presence of liquid coating

In this work, the impact of liquid coating on fluidized bed behavior is studied by performing DEM investigations. A wet coefficient of restitution model, accounting for the viscous and capillary forces in addition to the inelasticity of particles, is implemented in an open-source numerical tool — MFIX-DEM. The modified numerical tool is used to study the effect of the coating thickness and viscosity on the operation of a bed consisting of mono-sized solid spherical particles pre-coated with the same film thickness. The simulation results show that as the coating viscosity is increased, particles tend to stay close together, hence the fluidization behavior changes and the air passes through the system in the form of slugs. It is also shown that as the coating viscosity is increased the time-average wet coefficient of restitution, normal relative collision velocities, and bed height decrease. The effect of increasing the coating thickness is similar to the above, i.e. it results in a reduction of the time-averaged wet coefficient of restitution and normal relative collision velocities.