Abstract Mechanism modeling is an important method to quantify the flow heterogeneous phenomena of gas-liquid-solid fluidization. In this study, an improved meso-scale flow model, based on the energy minimum multi-scale (EMMS) theory, is developed to predict the global flow parameters of gas-liquid-solid fluidized bed. The improved EMMS model introduces gas bubble and solid particle accelerations, which make the model be capable of accurately predicting both the nominal-steady and the unsteady hydrodynamics of gas-liquid-solid fluidization. Compared with the reported models, the predicted results of this improved EMMS model are closer to the experiment data. Furthermore, the predictions indicate that both gas bubble acceleration and solid particle acceleration have an influence on the flow behavior of gas-liquid-solid fluidized bed, such as gas bubble diameter and relative slip velocity, which seriously affect the momentum and mass transfer between phases. Meanwhile, the accelerations of gas bubble and solid particle are not always equal to 0 at the nominal-steady state. Furthermore, the acceleration behavior of the unsteady-state gives a reasonable explanation for gas bubble coalescence. However, the relative error between model predictions and experimental data increases with the superficial gas velocity and the solid particle inertia. Thus this improved EMMS model is suitable for flow system at low superficial gas velocity with light and small solid particles.

中文翻译：

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一种改进的气-液-固流化床细观流动模型

摘要 机理建模是量化气-液-固流化流动非均质现象的重要方法。在这项研究中，基于能量最小多尺度（EMMS）理论，开发了一种改进的中尺度流动模型来预测气-液-固流化床的整体流动参数。改进后的EMMS模型引入了气泡和固体颗粒加速度，使得模型能够准确预测气-液-固流化的标称稳态和非稳态流体力学。与报道的模型相比，这种改进的EMMS模型的预测结果更接近实验数据。此外，预测表明气泡加速和固体颗粒加速都对气-液-固流化床的流动行为产生影响，如气泡直径和相对滑移速度，严重影响相间的动量和传质。同时，气泡和固体颗粒的加速度在标称稳态下并不总是等于0。此外，非稳态的加速行为给出了气泡聚结的合理解释。然而，模型预测和实验数据之间的相对误差随着表观气体速度和固体颗粒惯性而增加。因此，这种改进的 EMMS 模型适用于低表观气速、轻小固体颗粒的流动系统。气泡和固体颗粒的加速度在标称稳态下并不总是等于0。此外，非稳态的加速行为给出了气泡聚结的合理解释。然而，模型预测和实验数据之间的相对误差随着表观气体速度和固体颗粒惯性而增加。因此，这种改进的 EMMS 模型适用于低表观气速、轻小固体颗粒的流动系统。气泡和固体颗粒的加速度在标称稳态下并不总是等于0。此外，非稳态的加速行为给出了气泡聚结的合理解释。然而，模型预测和实验数据之间的相对误差随着表观气体速度和固体颗粒惯性而增加。因此，这种改进的 EMMS 模型适用于低表观气速、轻小固体颗粒的流动系统。