基于单元体理论的球床堆积结构与传热算法研究

Analysis of Structures and Heat Transfer for Packed Beds

以球床堆积结构为分析对象,利用离散单元法(DEM)进行数值模拟,实现球床的堆积并取得良好结果。随机堆积的球床中极少有颗粒达到最密集堆积状态,在靠近球床壁面处孔隙率迅速增加。对整个球床进行Voronoi单元体划分以分析球床局部结构,在大空间区域处堆积具有随机特点,在靠近壁面处呈现有序堆积特征。对每个单元体建立热平衡方程,实现对球床局部温度场的仿真,温度场计算结果与实验结果符合得很好。

In order to analyze the structures of packed beds, the discrete element method （DEM） reveals great advantages for numerical simulation. There are only few particles at densest state in random packed beds. Porosity increases rapidly with the oscillation at near-wall region. More local microstructure information will be obtained with Voronoi tessellation. Packing characteristics at the bulk region is random and ordered at the wall region instead. With homogenization assumption at Voronoi tessellation, a heat transfer model is established which can take the conduction between adjacent spheres and thermal radiation heat exchange into account and the numerical results agrees well with the experimental data.