Keynote Talk: Meso-Scale Modeling of Flow Regime Transitions in Gas-Solid Fluidized Beds
Wednesday, May 29, 2019 - 1:30pm to 1:55pm
Gas-solid fluidized bed is a typical nonlinear nonequilibrium, dissipative system, featuring meso-scale structures, e.g., bubbles and clusters. To capture the effects of these meso-scale structures, we proposed the structure-dependent multi-fluid model (SFM), thereby analyzed the fluidization behavior under conditions of extremum energy dissipation rate. Two flow regime transitions were investigated. In particular, we found that the criterion of minimum energy dissipation rate applies only to homogeneous, dilute flow states, whereas the energy minimization multi-scale (EMMS) stability condition well predicts the choking regime transition of circulating fluidized beds. Further, we proposed a new model for characterizing the length of clusters. By invoking a stability condition of maximum energy dissipation rate, the solution of SFM was found to well predict the minimum bubbling velocity and the voidage jump transition adhered to Geldart group A particles.