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Two-dimensional and three-dimensional computational studies of hydrodynamics in the transition from bubbling to circulating fluidised bed

Record type: Article

This paper applies two-fluid modelling (TFM) to a two dimensional and three dimensional circulating fluidised bed (CFB). An energy minimisation multiscale based drag model (EMMS) is compared with a classical drag model, namely the Gidaspow model in the light of experimental data from the CFB. The axial particle velocities and the radial volume fraction at different heights are considered. The specularity coefficient responsible for the tangential solid velocities at the walls is varied to study the effect on the downflow of particles at the wall. The work is further extended to explore the effects of velocity variation on the flow distribution showing the transition from a bubbling to a fast fluidising regime. Furthermore, the diameters of the bubbles observed within the bubbling regime are compared with the Davidson’s bubble diameter model for a range of particle diameters. Varying the specularity coefficient showed that a free slip boundary condition underpredicted the downflow of particles at the wall and to add slight roughness to the wall gave a closer representation. The predictions for the 2D and 3D CFB axial velocities were in good agreement with the experimental data but the 2D results slightly overpredicted the core velocity. The transition from a bubbling to a fast fluidising regime as expected occurred once the inlet velocity exceeded the terminal velocity. The equivalent bubble diameter from the simulations agreed well with the calculated bubble diameter from the model.

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Citation

Armstrong, Lindsay-Marie, Gu, Sai and Luo, Kai H. (2010) Two-dimensional and three-dimensional computational studies of hydrodynamics in the transition from bubbling to circulating fluidised bed Chemical Engineering Journal, 160, (1), pp. 239-248. (doi:10.1016/j.cej.2010.02.032).

More information

Published date: 15 May 2010
Keywords: cfd, hydrodynamics, circulating fluidised bed, eulerian, emms
Organisations: Engineering Sciences

Identifiers

Local EPrints ID: 73225
URI: http://eprints.soton.ac.uk/id/eprint/73225
ISSN: 1385-8947
PURE UUID: ba19f7a3-264c-499c-8d24-d93594b985c8

Catalogue record

Date deposited: 04 Mar 2010
Last modified: 18 Jul 2017 23:50

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Contributors

Author: Sai Gu
Author: Kai H. Luo

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