Gas-solid two-phase mixtures flowing upward through a confined packed bed

This paper deals with flows of a gas-solid two-phase mixture through a confined packed bed. Both experimental work and numerical modelling are performed on the behaviour of suspended particles within the packed bed. The experimental work is carried out with a non-intrusive Positron Emission Particle Tracking (PEPT) technique, which tracks particle motion at the single particle level for a prolonged period thus allows both the microscopic and macroscopic solids behaviour to be analysed under the steady-state conditions. A continuous based model is used to simulate the flow behaviour. The model uses a newly proposed porosity model and treats the suspended and packed particles as a binary mixture with the packed particles being at zero velocity. The results show that the model captures the main features of solids behaviour in terms of the radial distributions of the suspended particle concentration and the axial solids velocity. Both the experiments and modelling suggest that the wall effect on the motion of suspended particles be limited to a small region close to the wall (similar to 0.5-1 packed particle diameter). However, deviations exist between the model predictions and experiments; more work is therefore proposed to improve the interaction terms in the model between the suspended and packed particles.