Mesoscale bubbles exist inherently in bubbling fluidized beds and hence should be considered in the con-stitutive modeling of the drag force.The energy minimization multiscale bubbling(EMMS/bubbling)drag model takes the effects of mesoscale structures(i.e.,bubbles)into the modeling of drag coefficient and thus improves the coarse-grid simulation of bubbling and turbulent fluidized beds.However,its depen-dence on the bubble diameter correlation has not been thoroughly investigated.The hydrodynamic dis-parity between homogeneous and heterogeneous fluidization is accounted for by the heterogeneity index,Hd,which can be affected by choice of bubble diameter correlation.How this choice of bubble diameter correlation influences the model prediction calls for further fundamental research.This article incorporated seven different bubble diameter correlations into EMMS/bubbling drag model and studied their effects on Hd.The performance of these correlations has been compared with the correlation used previously by EMMS/bubbling drag model.We found that some of the correlations predicted lower Hd by order of a magnitude than the correlation used by the original EMMS/bubbling drag.Based on such analysis,we proposed a modification in the EMMS drag model for bubbling and turbulent fluidized beds.A computational fluid dynamics(CFD)simulation using two-fluid model with the modified EMMS/bub-bling drag model was performed for two bubbling and one turbulent fluidized beds.Voidage distribution,time averaged solid concentration and axial solid concentration profiles were studied and compared with the previous version of the EMMS/bubbling drag model and experimental data.We found that the right choice of bubble diameter correlations can significantly improve the results for CFD simulations.

Nouman Ahmad;Jianqiang Deng;Muhammad Adnan

Shaanxi Key Laboratory of Energy Chemical Process Intensification,Xi'an 710049,China;School of Chemical Engineering and Technology,Xi'an Jiaotong University,Xi'an 710049,China

中国化学工程学报（英文版）

[1]Nouman Ahmad;Jianqiang Deng;Muhammad Adnan-.Numerical investigation for the suitable choice of bubble diameter correlation for EMMS/bubbbling drag model)[J].中国化学工程学报（英文版）,2022(07):254-270

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