Effect of drag and friction models for the numerical prediction of particle mixing in Geldart Type B fluidized beds--颗粒学报PARTICUOLOGY

Fukada, T., Karte, G., & Pröll, T. (2026). Effect of drag and friction models for the numerical prediction of particle mixing in Geldart Type B fluidized beds. Particuology, 110, 320-330. https://doi.org/10.1016/j.partic.2025.12.015

Effect of drag and friction models for the numerical prediction of particle mixing in Geldart Type B fluidized beds

Toshiaki Fukada^a *, Gregor Karte^b, Tobias Pröll^b

a Central Research Institute of Electric Power Industry, 2-6-1 Nagasaka, Yokosuka-shi, Kanagawa, 2400196, Japan
b Institute of Chemical and Energy Engineering, BOKU University, Muthgasse 107/I, A-1190, Vienna, Austria

10.1016/j.partic.2025.12.015

Volume 110, March 2026, Pages 320-330

Received 29 June 2025, Revised 26 November 2025, Accepted 18 December 2025, Available online 3 January 2026, Version of Record 6 February 2026.

E-mail: t-fukada@criepi.denken.or.jp

Highlights

• The frictional stress model contributes to the mixing prediction when combined with the heterogeneous drag model.

• The drag model selection influences the probability density function of volume fraction rather than the bed height.

• The effects of the models increase as the fluidization number decreases.

Abstract

To investigate the effects of drag and frictional stress models in two-fluid model simulations, fluidized beds of Geldart type B particles are simulated, and the results are compared with experimental data for cases at lower fluidization numbers than those reported in the literature. The residence time distribution (RTD) of the particles is focused on because it reflects mixing behaviour that has a significant impact on the performance of fluidized bed reactors. The experimental results are reasonably modeled by a series of a plug flow reactor with axial dispersion and a continuous stirred tank reactor. Homogeneous and heterogeneous drag models are compared because the effects of the differences between them are unclear relative to those observed for Geldart type A particles. For the frictional stress, a model that reflects the effect of dilatation and compaction in BFBs is employed. Clear effects of the numerical models are observed when the fluidization number is reduced to 2.9. Although the simulated vertical distribution of average volume fraction is less sensitive to the drag model type than in the cases of Geldart type A particles, the simulated local distribution of the volume fraction is influenced. This influence leads to a change in the mixing behaviour. It is found that the frictional stress model effectively contributes to the prediction of mixing behaviour when combined with the heterogeneous drag model, which clearly represents bubbles. Without the frictional stress model, the mixing intensity is overestimated even with the heterogeneous drag model, indicating the importance of the combination of both models.

Graphical abstract

Keywords

Fluidized bed; Two-fluid model; Drag force model; Frictional stress model; Residence time distribution

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