ppt on cfd Euler and lagrangian modelling approahces.pptx

Different Modelling approaches.

1. Eulerian - Eulerian (Two Fluid Model) vs. Eulerian – Lagrangian ( Dense Disperse Phase Model)

2. Introduction 2 Fluidization is a physical phenomenon in which solid particles are made to flow like a fluid with the help of a gas or a liquid. Fluidization phenomenon is employed in chemical reactors (Fluidized bed Reactors). Due to due to their high heat and mass transfer rates, vigorous gas-solid mixing, low emission of pollutants FBRs have application in various industries: Fluid Catalytic Cracking Fischer- Tropsch (FT) synthesis coal/biomass combustion

3. Regimes in Fluidized Bed 3 Depending upon the velocity of fluidizing medium following flow regimes are possible in a Fluidized Bed.

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5. Geldart Particle Classification 5

6. Modelling Approaches 6

7. Modelling Approaches Following are Common Numerical Approaches for Gas – Solid Fluidized Bed Reactors: Two Fluid Model (TFM). Assume system consists of two continuum phases (Gas & Particles) Requires less computational time Relatively less accurate Small Scale (lab scale) Application Fine and Complex Solid Phase Dense Discrete Phase Model (DDPM). Requires long computational time Better Accuracy Industrial Scale Application Binary or poly disperse System 7

8. Present Research related with DDPM & TFM # Researcher Investigation Related with DDPM & TFM 1 Adamczyk et al. Adamczyk et al. compared the TFM and DDPM for a small-scale 3D circulating fluidized bed with Geldart B particles. The average pressure drop difference between experimental measurements and the complete DDPM geometry, simplified DDPM, and simplified TFM were 0.3, 0.23, and 0.4 kPa, respectively. They concluded that the DDPM could be used to predict the hydrodynamics behavior of gas-solid circulating fluidized bed reactors. 8

9. Present Research related with DDPM & TFM # Researcher Investigation Related with DDPM & TFM 2 Ostermeier et al. Ostermeier et al. compared the TFM, DDPM, and DEM for the hydrodynamics of a 3D lab scale bubbling bed with Geldart B particles. A comprehensive assessment and analysis of the grid-size independence, fluid time-step independence, sub-model (granular temperature) and model parameters ( specularity coefficient, particle number per parcel, and particle–wall reflection coefficient) were extensively investigated. It was shown that the TFM and DEM were able to predict realistic behavior in bubbling beds. However, the DDPM produced unrealistic predictions. 9

10. Present Research related with DDPM & TFM # Researcher Investigation Related with DDPM & TFM 3 Wu et al. Wu et al. compared the TFM and DDPM for the hydrodynamics of a 3D pilot-scale circulating bed with Geldart B particles. Sensitivity of some key modeling parameters, i.e., drag force, particle wall specularity coefficient and particle-particle restitution coefficient for the TFM, drag force, number of parcels, and the particle-wall reflection coefficients for the DDPM was investigated. The results show that the DDPM can predict the hydrodynamics in gas-solid circulating fluidized bed reactors. The conclusion made by Wu et al. is opposite to the conclusion of Ostermeier et al. 10

11. Thank You