Numerical investigation of mixing and orientation of non-spherical particles in a model type fluidized bed
Numerical investigation of mixing and orientation of non-spherical particles in a model type fluidized bed
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DOI：
10.1016/j.powtec.2014.03.046
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发表时间：
2014-05-01
影响因子：
5.2
通讯作者：
Kruggel-Emden, H.
中科院分区：
文献类型：
--
作者：
Oschmann, T.;Hold, J.;Kruggel-Emden, H.
基于三维离散元法与计算流体力学相结合的方法，对模型型流化床内的混合进行了数值研究。粒子运动用离散元法表示，粒子形状用聚类球和多面体表示。在cfd侧，单个颗粒周围的流体流动不被分解，而是在比颗粒大的细胞上平均。考虑各种拉长的颗粒形状，包括圆柱体、板形和长方体。与球形粒子作了比较。因此，主要的重点是混合，这是由Lacey指数，层高级数和平均颗粒方向来评估的。所研究的颗粒/流体系统具有丰富的细节。对于所考虑的不同颗粒形状，得到了较大的偏差。混合和床层高度的进展也受到颗粒形状的强烈影响。特别是当质量和投影面积发生变化时，形状表示精度对结果的影响较大。与流化床内部相比，在靠近容器壁的区域中，优选的颗粒方向可以得到显著的变化，这显然限制了仅根据外部的视觉观察来评估流化床内部过程的能力。(C) 2014 Elsevier B.V.版权所有
A numerical investigation of mixing in a model type fluidized bed is performed based on the three-dimensional discrete element method coupled with computational fluid dynamics (CFD). Particle motion is represented by the discrete element approach applying clustered spheres as well as polyhedrons for the particle shape representation. On the CFD-side fluid flow around individual particles is not resolved, but averaged over cells larger than the particles. Various elongated particle shapes are considered including cylinders, plates and cuboids. Comparisons to spherical particles are made. Thereby, the main focuses are mixing which is assessed by the Lacey index, bed height progression and averaged particle orientation. The investigated particle/fluid systems are rich in detail. Large deviations are obtained for the different particle shapes considered. Mixing as well as bed height progression is also strongly influenced by the particle shape. Especially the shape representation accuracy has strong influence on the results as mass and projection area get altered. Significant variations can be obtained for the preferred particle orientations taken up in regions close to the vessel walls in contrast to the interior of a fluidized bed which clearly limits the ability to evaluate processes inside fluidized beds based on visual observations from the exterior only. (C) 2014 Elsevier B.V. All rights reserved.