On time-averaged CFD modeling of circulating fluidized beds

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9 Citations (Scopus)

Abstract

CFD simulations of single-phase flows are regularly performed as steady-state utilizing closure models of varying complexity. On the contrary, dense gas-solid flows are usually computed as time dependent. These simulations commonly require a small time step and a fine mesh resulting in costly and time-consuming computations. In case of large industrial circulating fluidized beds (CFB), the steady-state CFD modeling would be an attractive alternative for the transient simulations, if reliable closure models for the time-averaged transport equations were available. The multiphase closure models developed for time-dependent CFB computations are not as such applicable to the steady-state approach. For instance, the fraction of the momentum transfer expressed by the velocities is significantly smaller in the steady-state models than in the transient ones. Therefore, the steady-state simulations rely more on the closure relations and especially on the models for inter-phase momentum transfer and for the Reynolds stress terms.

Several attempts to develop closure models for coarsemesh and steady-state simulations have been presented in the literature. In this paper, a novel steady-state simulation approach for a CFB process and a corresponding CFD model are introduced. A successful steady-state simulation for a test case is presented. Compared to the time-dependent simulations, the computing time is reduced by a factor of an order of 1000.
Original languageEnglish
Pages (from-to)363-373
Number of pages10
JournalInternational Journal of Nonlinear Sciences and Numerical Simulation
Volume13
Issue number6
DOIs
Publication statusPublished - 2012
MoE publication typeA1 Journal article-refereed

Keywords

  • CFB
  • CFD
  • time-averaged

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