Abstract

Computational fluid dynamics (CFD) coupled with a three-dimensional discrete element method (DEM) was applied to investigate the flow of corn-shaped particles in a cylindrical fluidized bed. The fluid phase was simulated with a $k-\epsilon$ turbulent model, and particle movement was simulated by the DEM. The particle motion coupled with the volume-averaged conservation of mass, momentum, and energy equations over a discretized domain. The corn-shaped particles were constructed as multi spheres (i.e., 4, 6, and 8 spherical elements). The particle-particle and particle-wall interactions were modeled using the Hertz-Mindlin no-slip contact model. The research was focused on the minimum velocity of fluidization (U_mf) and pressure drop (ΔP) of the corn particles with three different shapes. Additionally, the influence of the velocity of the fluid and particle shape on heat transfer was investigated. The simulation results showed that U_mf increases with an increasing number and arrangement of spherical elements. As the number of particles increases, U_mf and ΔP_max increase as well. The minimum fluid velocity of 2 U_mf is sufficient for the corn kernels to be thoroughly mixed.

摘要

计算流体动力学 (CFD) 与三维离散元法 (DEM) 相结合，用于研究圆柱形流化床中玉米形颗粒的流动。液相模拟采用$ķ-\epsilon$湍流模型，粒子运动由 DEM 模拟。粒子运动与离散域上的质量、动量和能量方程的体积平均守恒相结合。玉米形颗粒构造为多球体（即，4、6和8个球形元件）。使用 Hertz-Mindlin 无滑移接触模型对粒子-粒子和粒子-壁相互作用进行建模。研究的重点是三种不同形状的玉米颗粒的最小流化速度（U _mf）和压降（Δ P）。此外，还研究了流体速度和颗粒形状对传热的影响。仿真结果表明，U _mf随着球形元件数量和排列的增加而增加。随着粒子数量的增加，U _mf和ΔP _max也增加。2 U _mf的最小流体速度 足以使玉米粒充分混合。