Investigation of Gas-Solid Flows in a Spout Fluidized Bed on Drag and Solid Stress: CFD-DEM, TFM, and Experimental Validation

Abstract

In this work, experimental and numerical simulation methods are used to study the gas-solid two-phase flow in a three-dimensional rectangular spouted bed. In particular, the TFM and the CFD-DEM simulation results are compared with experimental data of the spouted bed. The influence of different drag models and friction stress models on the applicability of the simulation technology, Gidaspow, BVK, Koch-Hill, and Syamal-O'Brein drag models are investigated, respectively. Besides, the influence of the Syamal (S-R-O) and Srivastava-Sundaresan (S-S) friction stress models considering different transition points on the flow characteristics of particles in a spouted bed is also studied. Experimental verification shows that the Gidaspow drag, and S-S friction stress models are more consistent with experimental results. The fountain height predicted by CFD-DEM is closer to the experiment. It is found that the heterogeneous flow structure resulted in such a phenomenon in that the bubble cap blocked the gas flow pathway and increased the drag coefficient, while the bypass of the gas phase near the walls in the bubble reduced the drag coefficient.

A comprehensive comparison of Two-Fluid Model, Discrete Element Method and experiments for the simulation of single- and multiple-spout fluidized beds

“…Interphase drag models Bed type Guo et al (2021) (Guo et al, 2021) Gidaspow (Gidaspow, 1994) (TFM and CFD-DEM), Single-spout Beetstra et al (Beetstra et al, 2007), Koch and Hill (Hill et al, 2001) and O'Brien, 1987) Chen et al (2019) (Chen et al, 2019) Syamlal O'Brien (Syamlal and O'Brien, 1987) (TFM) and Multiple-spout DeFelice (Di Felice, 1994) (CFD-DEM) Almohammed et al (2014) (Almohammed et al, 2014) Gidaspow (Gidaspow, 1994), Wen and Yu (Wen, 1966), Single-spout Syamlal O'Brien (Syamlal and O'Brien, 1987) (TFM) and Koch and Hill (Hill et al, 2001 closures of frictional solids stresses in the literature (Zhao et al, 2021;Guo et al, 2021;Wang et al, 2014;Zhao et al, 2022) such as Johnson and Jackson (Johnson and Jackson, 1987), Srivastava and Sundaresan (Srivastava and Sundaresan, 2003) and Syamlal et al (Syamlal et al, 1993) strongly depend on empirical parameter of minimum solids volume fraction, a min s (the point, where frictional stresses become non-negligible), and are monotonically increasing functions with increasing solids volume fraction. In addition, particle-wall impacts in these TFM simulations are resolved with Johnson and Jackson (Johnson and Jackson, 1987) boundary condition.…”

“…However, there are a few comparative studies between TFM and CFD-DEM in the literature for the spout fluidized beds; Table 1 summarises these studies. Guo et al (Guo et al, 2021) used the interphase drag model of Gidaspow (Gidaspow, 1994) as the best fit for both TFM and CFD-DEM approaches and compared the results in terms of instantaneous bed height experimental data. Also, Chen et al (Chen et al, 2019) used different interphase drag models for TFM and CFD-DEM approaches, as denoted in the Table 1.…”

“…Due to discrete nature of the CFD-DEM method, it can fully resolve the contacts in all regions, however in the TFM approach, closures are needed to sufficiently consider these interactions. In the commonly used TFM approach for modelling of the spout fluidized beds (Guo et al, 2021;Chen et al, 2019;Almohammed et al, 2014;Zhao et al, 2021;Wang et al, 2014;Wu et al, yyyy;Zhao et al, 2016;Zhao et al, 2022), interstitial fluid effect on the kinetic-collisional solids stresses and pseudo-thermal energy flux has been ignored while studies of Wartha et al (Wartha et al, 2022), Agrawal et al (Agrawal et al, 2001) and Schneiderbauer et al reveal its importance. Furthermore, conventional frictional solids stresses models based on Coulomb's law (Schaeffer, 1987;Syamlal et al, 1993;Johnson and Jackson, 1987;Johnson et al, 1990;Srivastava and Sundaresan, 2003;Benyahia, 2008) manifest order-zero dependence on the rate of deformation in the quasi-static granular regime and are suitable just for dense regimes (Van Wachem et al, 2001).…”