CFD modeling of binary‐fluidized suspensions and investigation of role of particle–particle drag on mixing and segregation

Abstract

A model is presented for the prediction of the fluid dynamic behaviour of binary suspensions of solid particles fluidized by Newtonian fluids. The equations of motion for the fluid and solid phases are derived by extending the averaged two-fluid equations of change for identical spheres in Newtonian fluids developed by Anderson and Jackson and Jackson. A new closure relationship for the fluid-particle interaction force is employed and a new numerical algorithm is developed to control the solid compaction in each particle phase. The article also presents a comparison between three different equations of closure for the particle-particle drag implemented within the model. Predictions of the fluidization behavior obtained by the proposed model are validated against experimental results in terms of solid mixing and segregation, bed expansion and bubble dynamics. Two-dimensional CFD simulations are performed in a bed of rectangular geometry using ballotini with particle sizes of 200 and 350 lm.

A semi-empirical model for the drag force and fluid–particle interaction in polydisperse suspensions

“…Anderson and Jackson, 1967;Ding and Gidaspow, 1990) or discrete element method (DEM) (see e.g. Hoomans et al, 1996;Xu and Yu, 1997;Di Renzo and Di Maio, 2007) simulations of fluid-solid multiphase systems, allow highly complex features to be captured effectively, such as local variation of the flow field, porosity, component distribution (Owoyemi et al, 2007;Beetstra et al, 2007;Di Renzo et al, 2008) as well as combined hydrodynamics and heat transfer (see e.g. Kuipers et al, 1992;Di Maio et al, 2009;Zhou et al, 2009).…”

Study of the filter cake formed due to the sedimentation of monodispersed and bidispersed particles using discrete element method–computational fluid dynamics simulations

“…A numerical study of the packed bed/cake formation due to polydispersed particles requires a polydispersity particle–fluid interaction model. In the literature, there are a few polydispersed drag models . One of them is suggested by Beetstra which incorporates the effect of the polydispersity by considering a polydispersity correction factor (β j ) in the Stokes drag model.…”

Hydrodynamics of gas–solid fluidized bed of disparately sized binary particles

“…Some investigations have been conducted and several empirical correlations to account for inter-particle drag and the momentum transfer coefficient have been proposed. A comparison among three different equations of closure for the particle-particle drag has been presented recently (Owoyemi et al, 2007). The computational results show that when the particle-particle drag is accounted for, the degree of mixing within the bed is always overestimated.…”

“…Based on the extension of the two-fluid gas-solid model, CFD models of multi-component particle mixtures have been developed by some researchers, and the flow behavior of mixture particles has been predicted in bubbling fluidized bed or CFBs riser. The effect of the coefficient of restitution (Goldschmidt et al, 2001), the maximum particle packing and particle-particle drag (Owoyemi et al, 2007;Fan and Fox, 2008) on the segregation/mixing behavior was examined. The computational study, combined with the experiment (Mathiesen et al, 1999;Sun et al, 2005), significantly enhance the understanding of the underlying mechanisms and provide some necessary information.…”