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Partic. vol. 46 pp. 40-54 (October 2019)
doi: 10.1016/j.partic.2018.08.008

Numerical simulation of bubble behavior in a quasi-2D fluidized bed using a bubble-based EMMS model

Hao Wang, Youjun Lu*

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yjlu@mail.xjtu.edu.cn

Highlights

    • Bubble behavior in a Q2D fluidized bed was simulated using EMMS model. • A new correlation of the heterogeneous index in EMMS model was proposed. • We extended the flood-fill algorithm to search bubbles from 2D to a Q2D bed. • Results from empirical correlations, experiment and simulation are compared. • EMMS approach has higher accuracy in predicting properties of bubbles.

Abstract

Bubbles formed during chemical processes in fluidized beds govern the bed hydrodynamics and operational efficiency, thereby having a significant impact on their design and scale-up. In this study, a two-fluid model was used to simulate the bubble behavior in a quasi-two-dimensional fluidized bed within the bubble-based energy minimization multiscale (EMMS) approach. We performed experiments to verify the model and proposed a correlation of the heterogeneous index for various parameters to calculate the coefficient of drag for the bubble-based EMMS model. Moreover, the simulation results obtained from the homogeneous drag models and EMMS bubbling model were compared with experimental data and empirical correlations. The simulation results of the EMMS approach showed good agreement with the experimental data in the distribution of the vertical bubble velocity with chord length. Compared with the results from the homogeneous models, the distributions of vertical velocity and diameter of the bubbles predicted by the EMMS-bubbling model were in better agreement with empirical correlations. Moreover, the frequency distributions of bubble properties including bubble diameter, aspect ratio, and shape factor for different gas-inlet velocities were obtained.

Graphical abstract

Keywords

Energy minimization multi-scale approach; Heterogeneous index; Fluidized bed; Bubble