Abstract:

Complex gas-solid fluidization systems with multiscale dynamic structures have been widely encountered in process industries. Understanding their hydrodynamic characteristics is essential for the proper design and scale-up of such reactors. The energy-minimization multi-scale (EMMS) method provides a general modeling idea for the quantitative characterization of gas-solid heterogeneous systems. In this paper, a concise introduction of the EMMS drag model for coarse-grid continuum simulation was first provided, with emphasis on our recent progress on the improvement and generalization of the drag model. The extension and application of the population balance model (PBM) in quantifying the dynamic evolution of bubbles or clusters in the fluidized beds were then discussed, followed by an overview of the integration of PBM and structure-dependent models. Finally, the application of EMMS theory in predicting the macroscopic steady-state dynamics of complex gas-solid reactors was also reviewed, together with the development of the steady-state EMMS models applicable for various regimes, the construction of generalized operating diagram and the realization of full-loop modeling of gas-solid circulating fluidized bed reactors.

Key words: computational fluid dynamics, drag model, fluidization, multiscale, mesoscale, EMMS

摘要：

气固流化床反应器是典型的具有多尺度非均匀动态结构的复杂系统。实现对该类反应器定量描述和定向调控的关键是深入了解系统内介尺度结构的形成和演化特征。能量最小多尺度（EMMS）方法为气固非均匀系统的量化表征提供了一种通用的建模思路。首先回顾了EMMS理论在构建曳力本构关系方面的应用，重点介绍了本课题组在EMMS曳力模型普适化方面所做的部分工作；随后对介尺度结构时空动态演化行为的群平衡建模方法进行了论述，并给出了群平衡和结构曳力模型相耦合的连续介质模拟框架；最后讨论了EMMS原理在预测反应器宏尺度动力学方面的应用，包括模型在不同流域的拓展、操作相图的绘制以及循环流化床的全回路稳态建模方法等。

关键词: 计算流体力学, 曳力模型, 流态化, 多尺度, 介尺度, 能量最小多尺度