Studies of Gas Velocity And Particles Size Effects on Fluidized Bed Hydrodynamics with Cfd Modeling and Experimental Investigation

Abstract

With applying Computational Fluid Dynamics (CFD) techniques, hydrodynamics of a twodimensional non-reactive gas-solid fluidized bed reactor was investigated. A multi fluid Eulerian model incorporating the kinetic theory for solid particles was applied to simulate the unsteady state behavior of this reactor and momentum exchange coefficients were calculated by using the Syamlal-O'Brien drag functions. A suitable numerical method that employed finite volume method applied to discritize the equations. Simulation results also indicated that small bubbles were produced at the bottom of the bed. These bubbles collided with each other as they moved upwards forming larger bubbles. Also, solid particles diameter and superficial gas velocity effect on hydrodynamics were studied. Simulation results were compared with the experimental data in order to validate the CFD model. Pressure drops and bed expansion ratio as well as the qualitative Gas-Solid flow patterns predicted by the simulations were in good agreement with experimental measurements at superficial gas velocities higher than the minimum fluidization velocity. Furthermore, this comparison showed that the model can predict hydrodynamicsbehavior of gas solid fluidized bed reasonably well.

CFD Modeling and Simulation of Hydrodynamics in a Fluidized Bed Dryer with Experimental Validation

“…where τ is Reynolds stress tensor, g is gravitational constant, and (−ε s ∇p + β gs ( ν g − ν s )) is an interaction force (drag and buoyancy forces) representing the momentum transfer between gas and solid phases [7,9,[21][22][23][24]. The interphase momentum transfer is an important term in the modeling of gas-particle interactions, since particle fluidization results from the drag exerted by the interstitial gas on the particulate phase.…”

“…Here v s,w is the particle slip velocity, e ss,w is the restitution coefficient at the wall, and ε s,max is the volume fraction for the particles at maximum packing [19][20][21][22][23][24][25]27]. …”

“…Hamzehei et al [19][20][21][22] investigated unsteady flow and heat transfer in a gas-solid fluidized-bed reactor. Also particle sizes, gas velocity, and drag models effects on hydrodynamics and heat transfer of a nonreactive gas-solid fluidized bed reactor were studied experimentally and computationally.…”

Computational and experimental studies on bed dynamics of a gas–solid fluidized bed using Geldart-A particle: A comparison

“…Experimental study on the hydrodynamics of gas-fluidized beds where the effects of particle size and interparticle force are studied Valverde (2003aValverde ( , 2003b. Hydrodynamic behaviours of gassolid fluidized bed reactor investigated by Taghipour, Ellis, and Wong (2005) and Hamzehei, Rahimzadeh, and Ahmadi (2010) using multi-fluid Eulerian model where the effects of particle size and superficial gas velocity are studied. In this work, the effects of particle sizes have been 4 studied at different inlet air velocities to know the hydrodynamics of gas-solid fluidized beds.…”

Hydrodynamic studies on fluidization of Red mud: CFD simulation

“…The results obtained from a 'discrete particle method' (DPM) are qualitatively compared with that of a multi fluid computational fluid dynamic (CFD) model by them. Hydrodynamic behaviors of nonreactive gas-solid fluidized bed reactor are investigated by using multi fluid Eulerian model where the effects of particle size and superficial gas velocity are studied by researchers [9,10]. Hydrodynamics of a gas-solid tapered fluidized bed with CFD simulations are reported [11].…”