Validation of an improved two-fluid model with particle rotation for gas-solid fluidized bed

Abstract

Gas-solid fluidized beds are widely applied in chemical and process engineering. It is of significance to establish a reasonable and effective mathematical model to explore the hydrodynamics of gas-particle system for industrial applications. As a less computationally demanding alternative to the discrete descriptions, two-fluid model considering kinetic theory of granular flow is often adopted to describe the fluidized behaviors of particles, but it cannot characterize the rotation of particles and its influence on the fluidized behaviors. In this study, to address the rotation effect of the fluidized particles, a two-fluid model combining the classical fluid and micropolar fluid is established, namely CMTFM. In the CMTFM, classical fluid is used to describe the motion of gas phase, while micropolar fluid is adopted to describe the motion of particle phase, and the rotation of particles and its influence on the hydrodynamics of the gas-particle system are characterized by the degree of freedom of microrotation and the improved drag force based on micropolar viscosities. In the calculation of the gas-solid bubbling fluidized bed, we investigated the influence of the microstructure parameters, particle-particle collision restitution coefficient and inlet velocity, and the results are compared to those from TFM model and experiments. Through the analysis, it manifests that pressure drop and expansion height of the fluidized bed under the consideration of the microrotation effect are closer to the experiments, which demonstrates the feasibility and advantage of the classical-micropolar two-fluid model.