Investigation of hydrodynamics and heat transfer in pseudo 2D spouted beds with and without draft plates

S H Hosseini,G Ahmadi,M Fattahi

doi:10.1590/0104-6632.20170344s20150588

S H Hosseini, G Ahmadi + Show 1 more

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https://doi.org/10.1590/0104-6632.20170344s20150588

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Abstract

Abstract In the present study, hydrodynamics and gas to particle heat transfer in pseudo two dimensional spouted beds (2DSB) with and without draft plates were investigated using the Eulerian-Eulerian approach. The main objective of the study was to provide an understanding of effects of the presence of draft plates on the hydrodynamics and heat transfer behavior of solid particles in the spouted beds. To validate the model, the predicted mean particle vertical velocity at the bed axis, the lateral profiles of vertical particle velocity at different bed heights for both systems, and the particle velocity vector fields in the beds were compared with the experimental measurements. A close agreement between the CFD results and the experimental data was found for both systems. The simulation results showed that the particle volume fraction in the spout and fountain regions of the spouted bed with draft plates is considerably lower than that in a conventional spouted bed (without draft plates). Simulation results also showed significant differences between the temperature distributions of gas and solid phases in spouted beds with and without draft plates.

Highlights

The original spouted bed was developed in 1954 as an alternative method of drying for a badly slugging fluidized bed of moist wheat particles
Realizing that the technique could have wider application, the NRC group studied the characteristics of spouted beds for a variety of solid materials, with both air and water as spouting media
A spouted bed typically displays three distinct regions: a central spout, annulus or downcomer, and a fountain region (Epstein and Grace, 2011).hydrodynamics, heat transfer and mass transfer behaviours of spouted beds are quite different from fluidized beds and due to high circulation and stable behavior of particles, spouted beds have high performance

Summary

Introduction

The original spouted bed was developed in 1954 as an alternative method of drying for a badly slugging fluidized bed of moist wheat particles. Because of the vigorous particle circulation, much hotter air than in conventional wheat driers could be used without damaging the grain. On the basis of this preliminary study, they asserted that the mechanism of flow of solids as well as of gas in this technique is different from fluidization, but it appears to achieve the same purpose for coarse particles as fluidization does for fine materials. A spouted bed typically displays three distinct regions: a central spout, annulus or downcomer, and a fountain region (Epstein and Grace, 2011).hydrodynamics, heat transfer and mass transfer behaviours of spouted beds are quite different from fluidized beds and due to high circulation and stable behavior of particles, spouted beds have high performance. Among the different approaches for modeling the multiphase flows, the Eulerian-Eulerian approach, in which both phases are treated as interpenetrating continua

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