On time-averaged CFD modeling of circulating fluidized beds

Research output: Contribution to journalArticleScientificpeer-review

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

Fingerprint

Fluidized Bed
charge flow devices
Fluidized beds
beds
Computational fluid dynamics
closures
Closure
Modeling
simulation
Simulation
Momentum transfer
momentum transfer
Fluidized bed process
Model
Momentum
Flow of solids
single-phase flow
solids flow
CFD Simulation
Reynolds Stress

Keywords

  • CFB
  • CFD
  • time-averaged

Cite this

@article{c1a9e06ab68b428b9a6666573478a909,
title = "On time-averaged CFD modeling of circulating fluidized beds",
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.",
keywords = "CFB, CFD, time-averaged",
author = "Veikko Taivassalo and Sirpa Kallio and Juho Peltola",
year = "2012",
doi = "10.1515/ijnsns-2012-0025",
language = "English",
volume = "13",
pages = "363--373",
journal = "International Journal of Nonlinear Sciences and Numerical Simulation",
issn = "1565-1339",
publisher = "De Gruyter",
number = "6",

}

TY - JOUR

T1 - On time-averaged CFD modeling of circulating fluidized beds

AU - Taivassalo, Veikko

AU - Kallio, Sirpa

AU - Peltola, Juho

PY - 2012

Y1 - 2012

N2 - 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.

AB - 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.

KW - CFB

KW - CFD

KW - time-averaged

U2 - 10.1515/ijnsns-2012-0025

DO - 10.1515/ijnsns-2012-0025

M3 - Article

VL - 13

SP - 363

EP - 373

JO - International Journal of Nonlinear Sciences and Numerical Simulation

JF - International Journal of Nonlinear Sciences and Numerical Simulation

SN - 1565-1339

IS - 6

ER -