Detailed analysis of recent drag models using multiple cases of mono-disperse fluidized beds with Geldart-B and Geldart-D particles

The Gidaspow drag model that combines the Ergun and Wen−Yu empirical correlations is widely used in gas−solid two-phase flows in the literature. It is believed that fluid−particle drag should be a continuous function of both the solid volume fraction and the Reynolds number. In the Gidaspow model, however, the transition of the two correlations is discontinuous at the solid volume fraction of 0.2. A few later models smoothed this transition, though with arbitrarily chosen functions and parameters. A new drag model with a transition based on the inertial number is proposed in this paper. Predictions of this new drag model were compared to those from other drag models in the settings of fluidization of Geldart B and D particles and a riser. Simulation results show that the inertial number-based drag model is a viable and accurate alternative to the original Gidaspow model and the later models.

Section: Resultssupporting

confidence: 87%

“…A similar conclusion was also obtained by Stanly and Shoev. 39 The results of Gidaspow 8 and Huilin−Gidaspow 14 drag models are almost the same. The result of the new INB drag model is very close to those of the other models.…”

Section: Bfb With Geldart Dmentioning

confidence: 78%

Inertial Number-Based Drag Model and Its Application in Simulating the Fluidization of Geldart B and D Particles

Liu

Guo

Yin

et al. 2022

“…In the present cases, the particles in the fluidized bed belong to Geldart-D particles . Stanley and Shoev numerically simulated the flow behavior of the fluidized beds using the two-fluid model and mesh sizes approximately 1.5–2 times the particle diameters. They compared the simulation results with experiments conducted by Goldschmidt et al and Muller et al and found good agreement between the simulation and experimental values.…”

Section: Model Descriptionmentioning

confidence: 99%

Numerical Prediction of Hydrodynamic Characteristics of Wet Particles and Power-Law Fluids in a Fluidized Bed Using the Dynamic Restitution Coefficient

Tian,

Wang,

Peng

et al. 2024

The hydrodynamic characteristics of the non-Newtonian fluid and wet particles are studied by a kinetic theory-based two-fluid approach. The dynamic restitution coefficient for wet particles is applied to calculate the instantaneous restitution coefficient, which is a function of the Stokes number calculated based on the local strain rate. Furthermore, the dynamic critical Stokes number is utilized to judge whether particles rebound after a collision. In addition, a modified drag model is applied to study interphase interactions. The effects of both the interstitial fluid on the wet particle collision and particle concentration on the rheological properties of the non-Newtonian fluid are considered. The results show that the interstitial liquid viscosity between colliding particles is less than the liquid-phase viscosity. The critical Stokes number decreases with the increase of rheological parameters. The predicted critical Stokes number in non-Newtonian fluids is between 7 and 8, which is in agreement with the experimental results.

“…In Geldart-A particles, the EMMS model offers more precise simulation rather than the Gidaspow model . In addition, for Geldart-B particles, the Gidaspow model can accurately predict gas–solid flow. , Figure presents the prediction based on the Gidaspow and EMMS drag models. With superficial gas velocity increases between 7 and 11 m/s, axial distributions of the simulated solids holdup for both models are close to the experimental data.…”

Section: Simulation Descriptionmentioning

confidence: 99%

Riser Reactor with a Multistage Oxygen Feeding Strategy for the Oxidative Coupling of Methane

Cai,

Chang,

Liu

et al. 2024

Oxidative coupling of methane (OCM) is characterized by a high temperature and a strongly exothermic reaction. However, the desired C 2 H 4 may easily react to unwanted oxidation products. Due to vigorous gas−solids contacting, excellent heat and mass transfer characteristics, and low gas back-mixing, the riser reactor is adopted in the OCM process. Hydrodynamics and reactor performance of the riser are investigated by simulation. In the riser reactor, the excellent hydrodynamics results in a decrease in consecutive reactions and the heat is released. The multistage oxygen feeding strategy is proposed to improve reactor performance. Compared with the single-stage oxygen feeding, the C 2 yield increases by 9.5% in the three-stage oxygen feeding. Moreover, the optimal position of oxygen feeding is presented.