Comprehensive investigation and comparison of TFM, DenseDPM and CFD-DEM for dense fluidized beds

Eulerian-Eulerianand Eulerian-Lagrangianmodels arewidely appliedtonumerically investigate dense solidgas fluidized bed systems. However, only a few studies in the existing literature focus on a detailed analysis and comparison of the different modeling approaches. Therefore, the objective of this study is to investigate the Two Fluid Model (TFM), the Dense Discrete Phase Model (DDPM), and the Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) with respect to a comprehensive independency study, a sensitivity analysis of the respective submodels and model parameters, a comparison of the simulation results between the differentmodeling approaches, as well as their computational demand. The simulations represent a test case of a pilot plant scale reactor (inner diameter up to 387 mm, height 900 mm), which is used within a thermochemical energy storage system (CaO þ H2O $ CaðOHÞ 2). Monodisperse Geldart B powder (particle diameter 200 lm, particle density 2500 kg/m3, sphericity factor 0.8) is fluidized with water vapor (ideal gas, temperature 400 C, inlet velocity 0.495 m/s). Grid size, fluid and particle time step, and particle clustering are considered for the independency study. Different wall boundary conditions and calculation methods for the granular temperature are investigated for the TFM. For the DDPM, different wall boundary conditions are analyzed as well, while for the CFD-DEM, simulations with two different DEM submodels (Hertzian and Hookean collisionmodel) and a sensitivity analysis of the respectivemodel parameters are included. Results showthat the TFMand the CFD-DEMare able to predict qualitatively and quantitatively similar gas and particle flowfields, if TFMmodel parameters are set appropriately.However, a quite different pressure drop and bed expansion is observed for eachmodel. TheDDPMdoes not result in realisticflowfields for the investigated test case, despite predicting a pressure drop and bed expansion similar to the TFM. The presentedfindings leadtothe conclusionthatmodel validation should not only be basedonglobal observable values like pressure drop and bed expansion, but also on local particle flow fields and bubbling behavior.     «

Eulerian-Eulerianand Eulerian-Lagrangianmodels arewidely appliedtonumerically investigate dense solidgas fluidized bed systems. However, only a few studies in the existing literature focus on a detailed analysis and comparison of the different modeling approaches. Therefore, the objective of this study is to investigate the Two Fluid Model (TFM), the Dense Discrete Phase Model (DDPM), and the Computational Fluid Dynamics-Discrete Element Method (CFD-DEM) with respect to a comprehensive indep...     »