CFD simulation of a spouted bed: Comparison between the Discrete Element Method (DEM) and the Two Fluid Model (TFM)

Abstract

Highlights  A prismatic spouted bed was modelled using CFD.  A comparison between discrete element method (CFD-DEM) and two fluid model (CFD-TFM) was performed.  Results in terms of accuracy and computational effort were evaluated for each approach.  CFD-DEM provides a better prediction of maximum particle velocity.  CFD-TFM predicts better the height of the fountain. A spouted bed was simulated through two Computational Fluid Dynamic models: CFD-TFM and CFD-DEM. The two models were compared and validated with data from literature, showing good agreement between experimental and simulated results. Both models were able to predict the dynamics of the bed from the static situation to stable spouting conditions, even though some discrepancies in the solid volume fraction or velocity profiles were observed. Overall, CFD-DEM reproduced better the experimental measurements, and, since the computational effort was proved to be similar in both cases due to the low number of particles in the bed, it was preferred to describe the present spouted bed. In larger systems, however, CFD-DEM might not be so convenient, requiring the evaluation of the degree of accuracy and the computational costs prior to the application of this or alternative models.

Sensitivity analysis and validation of a Two Fluid Method (TFM) model for a spouted bed

“…The phase-coupled SIMPLE algorithm was applied for the pressure-velocity coupling with the discretisation schemes as described in (Moliner et al, 2018b).…”

“…A complete sensitivity analysis was carried out as follows: first, an initial set of reference parameters was defined on the basis of previous simulations (Moliner et al, 2018b). Table 3 lists the reference and tested options for all the studied parameters.…”

Mathematical Modeling and Pointwise Validation of a Spouted Bed Using an Enhanced Bed Elasticity Approach

“…In the context of mathematical modeling of spouted beds, two main kinds of model can be found in literature: (i) Eulerial-Lagrangian models [17,20,[22][23][24][25], also known as CFD-discrete element model (CFD-DEM) or discrete particle models (DPM), where the solid phase is modeled by solving equations of motion for each individual particle, and the multiphase interaction is included through interfacial momentum exchange sub-models; and (ii) Eulerian-Eulerian models [26][27][28], usually referred as Euler-2-phase (E2P) or two-fluid model (TFM), where both the solid and gas phases are treated as interpenetrating continuum, and hence, the multiphase interactions are included through effective volumetric momentum exchange sub-models. The CFD-DEM models are usually limited by the available computational resources [29], and thus, their applicability is currently constrained to small scale units.…”

Estudo Cinético De Diferentes Cultivares Da Biomassa Do Capim Elefante (Pennisetum Purpureum Schum.)

“…Os leitos de jorro e leito fluidizado têm sido objeto de intensa pesquisa nas últimas décadas. Os termos jorrando e leito de jorro foram dados pelo Conselho Nacional de Pesquisa (NRC) do Canadá para descrever um dispositivo inovador baseado em tecnologias de fluidização (Moliner et al, 2018). Mathur e Gishler (1955) descreveram esta tecnologia como "um mecanismo de fluxo para sólidos e gás diferente da fluidização, mas atinge o mesmo propósito para partículas grossas, como a fluidização faz para materiais finos".…”