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Simulation of dynamic behavior in bubbling fluidization

Progress in Natural Science:Materials International 2001年第10期 54-60页

作者：欧阳洁李静海 Applied Mathematics Department Beijing 100080 China Chinese Academy of Sciences Institute of Chemical Metallurgy Northwestern Polytechnical University Xi’an 710072

Both the behavior of bubbles in the distributor with several orifices and the sensitive dependence of bubbling fluidization on initial condition have been simulated by particle-motion-resolved discrete model in which the gas flow is obtained by solving the Navier-Stokes equation including two-phase interaction, and the motion of solid phase is obtained by decomposing the motion of each particle into collision process and suspension process. Compared with the pseudo-fluid models and previous discrete models, this model is authentic and can be widely used for simulating bubbling fluidization.

关键词： simulation bubbling fluidization particle-motion-resolved discrete model.

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Micro-flow structure at regime transition from bubbling to turbulent fluidization in a fluidized bed

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Particuology 2024年第6期89卷 117-130页

作者： Chaoyu Yan Yue Yuan Xiaoyang Wei Jesse Zhu State Key Laboratory of Heavy Oil Processing Beijing Key Laboratory of Process Fluid Filtration and SeparationCollege of Mechanical and Transportation EngineeringChina University of PetroleumBeijing 102249China China Beacons Institute The University of NottinghamNingbo315100China Department of Chemical and Biochemical Engineering University of Western OntarioLondonOntarioN6A 5B9Canada

Gas-solid fluidized beds have found extensive utilization in frontline manufacturing,in particular as low-velocity *** fluidization status,the bubbling or turbulent flow regime and the transition in between,determine the system performance in practical *** the convoluted hydrodynamics are quantitively evaluated through numerous data-processing methodologies,none of them alone can reflect all the critical information to identify the transition from the bubbling to the turbulent ***,this study was to exploit a coupling data processing methodology,in the combination of standard deviation,power spectrum density,probability density function,wavelet transform,and wavelet multiresolution method,to jointly explain the micro-flow structure at the regime transition from bubbling to turbulent *** transient differential pressure fluctuation was measured for the evaluation in a fluidized bed(0.267 m i.d.×2.5 m height)with FCC catalysts(d_(p)=65μm,ρ_(p)=1780kg/m^(3))at different superficial gas velocities(0.02–1.4 m/s).The results show that the onset of turbulent fluidization starts earlier in the top section of the bed than in the bottom *** wavelet decomposition displays that the fluctuation of differential pressure mainly concentrates on the sub-signals with an intermediate frequency *** sub-signals could be synthesized into three types of scales(micro-scale,meso-scale,and macro-scale),representing the multi-scale hydrodynamics in the fluidized *** micro-scale signal has the characteristic information of bubbling fluidization,and the characteristic information of turbulent fluidization is mainly represented by the meso-scale *** work provides a systematic comprehension of fluidization status assessment and serves as an impetus for more coupling analysis in this sector.

关键词： Flow regime transition bubbling fluidization Turbulent fluidization Micro-flow structure Differential pressure fluctuation

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Validation of Dimensionless Parameters for Distinguishing between Homogeneous and bubbling fluidizations

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Open Journal of Fluid Dynamics 2021年第2期11卷 81-97页

作者： Kenya Kuwagi Atsuto Kogane Yui Sasaki Hiroyuki Hirano Department of Mechanical Systems Engineering Okayama University of Science Okayama Japan Department of Applied Chemistry and Biotechnology Okayama University of Science Okayama Japan

The difference between homogeneous and bubbling fluidization behaviors has been studied for the past 70 years, where several researchers have reported on the influence of interparticle forces in fluidization. Although interparticle forces such as van der Waals forces are evident in a real system, these forces are not the determinant in homogeneous fluidization, which can be simulated without any interparticle forces. In our previous study, the difference in fundamental mechanisms of the two fluidization states was analytically determined with a dimensionless gravity term, comprising the Reynolds number, Archimedes number, and density ratio. Nevertheless, some researchers insist that interparticle forces are dominant and a hydrodynamic force is not dominant. In this study, a dimensional analysis was applied to obtain a dominant parameter for distinguishing two fluidizations. Furthermore, some parameters were examined by comparing the experimental data in previous studies. The results indicated that hydrodynamic force is the dominant factor and the dimensionless gravity term is the dominant parameter in differentiating the two fluidized states.

关键词： bubbling fluidization Homogeneous fluidization Aggregative Particulate Dimensional Analysis

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A model for predicting the segregation directions of binary Geldart B particle mixtures in bubbling fluidized beds

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Particuology 2024年第7期90卷 340-349页

作者： Chenmin Liu Yuemin Zhao Yanjiao Li Yuqing Feng Chenlong Duan Chenyang Zhou Liang Dong Key Laboratory of Coal Processing and Efficient Utilization Ministry of EducationChina University of Mining and TechnologyXuzhou221116China School of Chemical Engineering and Technology China University of Mining and TechnologyXuzhou221116China Mineral Resources Business Unit CSIROClaytonVIC 3169Australia

In gas fluidization processes involving different types of particles,the mixing or segregation behavior of the solid mixture is crucial to the overall outcome of the *** study develops a model to predict the segregation directions of binary mixtures of Geldart B particles with density and size differences in bubbling fluidized *** proposed model was established by combining the particle segregation model,a previous particle segregation model,with a derived bed voidage equation of the bubbling fluidization based on the two-phase *** model was then analyzed with different function graphs of the model equations under various *** results indicated that an increase in gas velocity or volume fraction of larger particles would strengthen size segregation,causing the larger and less dense components to *** validate the model,42 sets of data collected from 6 independent literature sources were compared with the predictions of the *** the gas velocities were below 3.2 times the minimum gas velocity,the predictions were consistent with experimental *** study has shed new light on the mechanisms of particle segregation in binary fluidized systems and provides a theoretical foundation for designing and manipulating gas-solid fluidized reactors.

关键词： Particle segregation Binary mixture bubbling fluidization Geldart B particles Two-phase theory

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