Effects of flow behavior index and consistency coefficient on hydrodynamics of power-law fluids and particles in fluidized beds

Abstract

Flow behaviors of particles and power-law fluids were numerically simulated by means of Euler-Euler model with kinetic theory of granular flow in liquid-solid fluidized beds, and effects of flow behavior index (n) and consistency coefficient (K) were studied. The simulation results were compared with the experimental measurements, and good agreements were achieved. The effective viscosity of the shear-thinning fluid decreases as it flows through the expanded bed due to the increase in fluid strain rate. Unlike the homogeneous distributions of particles in Newtonian liquid fluidized beds, four regions for particle flow were observed along the bed height when a non-Newtonian fluid acts as the fluidizing agent, which indicates the non-uniformity of particles distribution. With the decrease of n, the enhancement of shear-thinning characteristics of the fluidizing agent thickens the relative inlet region and enhances the non-uniformity of particles along the bed height. The increase of n accelerates the circulation of particles in the fluidized bed, which speeds up the renewal of the particulate materials throughout the reactor space. The increase in K increases the apparent viscosity of the fluidizing agent. The bed height increases and the average solid volume fraction decreases. However, the influence of K on the non-uniformity of particles in the bed is less significant than that of n.