The parametric sensitivity of fluidized bed reactor simulations carried out in different flow regimes

Abstract

Fluidized bed simulations carried out within the Kinetic Theory of Granular Flows framework utilize a number of model coefficients which are strongly case dependent and difficult to determine accurately. The most important of these are the specularity coefficient (the degree of friction at the wall) and the particle-particle restitution coefficient (inelasticity of inter-particle collisions). This paper demonstrated that modification of these coefficients can trigger a regime change in very narrow and fast risers, thereby introducing a great amount of uncertainty. For situations sufficiently far from the dilute transport regime, however, sudden regime changes were not observed and the influence of these unknown parameters is more systematic. It was shown that in the case of wide bubbling beds, the effect of these unknown model coefficients can become negligible, making these reactors attractive for simulation studies. Faster and narrower geometries, on the other hand, exhibited greater sensitivity to changes in the specularity coefficient and particle-particle restitution coefficient, thereby introducing ever-increasing quantities of uncertainty stemming from these unknown model coefficients.