Application of Wray-Agarwal Turbulence Model for Numerical Simulation of Gas-Solid Flows in Circulating Fluidized Bed Risers

In recent decades, increasing attention has been paid on accurate modeling of circulating fluidized bed (CFB) risers to provide valuable guidance to design, optimization, and operation of reactors. Turbulence model plays an important role in the accurate prediction of complex gas-solid flows. Recently developed Wray-Agarwal (WA) model is a one-equation turbulence model with the advantages of high computational efficiency and competitive accuracy with two-equation models. In this paper for the first time, the Eulerian-Eulerian approach coupled with different turbulence models including WA model, standard κ-ε model, and shear stress transport (SST) κ-ω model is employed to simulate two-phase flows of gas phase and solid phase in two CFB risers, in order to assess accuracy and efficiency of WA model compared to other well-known two-equation models. Predicted gas-solid flow dynamic characteristics including the gas-solid volume fraction distributions in radial and axial directions, pressure profiles, and solid mass flux distributions are compared with data obtained from an experiment in detail. The results demonstrate that the WA model is very promising for accurate and efficient simulation of gas-solid multiphase flows.