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particle shape effect on hydrodynamics and heat transfer in spouted bed:A CFD-DEM study

Particuology 2022年第10期20卷 10-21页

作者： Dianyu E Peng Zhou Suya Guo Jia Zeng Jiaxin Cui Youyuan Jiang Yuanxiang Lu Zeyi Jiang Zhengquan Li Shibo Kuang Jiangxi Provincial Key Laboratory for Simulation and Modelling of Particulate Systems Jiangxi University of Science and TechnologyGanzhou 341000China Ironmaking Plant Xiangtan Iron and Steel Corporation of Hunan HualingXiangtan 411101China School of Energy and Environmental Engineering University of Science and Technology BeijingBeijing 100083China ARC Research Hub for Computational particle Technology Department of Chemical EngineeringMonash UniversityClaytonVIC 3800Australia

Spouted bed has drawn much attention due to its good heat and mass transfer efficiency in many chemical *** the flow patterns and heat and mass transfer inside a spouted bed can help optimize the spouting ***,in this study,the effects of particle shape on the hydrodynamics and heat transfer in a spouted bed are *** is done by using a validated computational fluid dynamics-discrete element method(CFD-DEM)model,considering volume-equivalent spheres and oblate and prolate *** results are analysed in detail in terms of the flow pattern,microstruc-ture,and heat transfer *** numerical results show that the prolate spheroids(Ar=2.4)form the largest bubble from the beginning of the spouting process and rise the highest because the fluid drag forces can overcome the interlocking and particle-particle frictional *** with spherical particles,ellipsoidal spheroids have better mobility because of the stronger rotational kinetic energy resulting from the rough surfaces and nonuniform *** addition,the oblate spheroid system exhibits better heat transfer performance benefiting from the larger surface area,while prolate spheroids have poor heat transfer efficiency because of their orientation *** findings can serve as a reference for optimizing the design and operation of complex spouted beds.

关键词： Spouted bed Gas-solid flow particle shape CFD-DEM Heat transfer

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Effects of particle shape and packing style on ethylene oxidation reaction using particle-resolved CFD simulation

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Particuology 2023年第11期82卷 87-97页

作者： Yao Shi Hao Chen Wenyao Chen Guanghua Ye Jin Qu Jinbing Li Xinggui Zhou Xuezhi Duan State Key Laboratory of Chemical Engineering School of Chemical EngineeringEast China University of Science and TechnologyShanghai200237China Yanshan Branch of Beijing Research Institute of Chemical Industry China Petroleum&Chemical Company(Sinopec Corp.)Beijing102500China

Gaining in-depth insights into the effects of particle shapes and packing style on ethylene oxidation reaction is of paramount industrial *** this work,reactor models of five packing structures with different particle shapes and three packing structures with different packing styles are established by employing software Blender and COMSOL Multiphysics to explore how the reaction-diffusion behaviors affect ethylene oxidation *** reliabilities of rigid body dynamics model and particle-resolved reactor model are verified by comparing simulated and experimental pressure drops and ethylene *** all the five packing structures with laminar flow conditions,the high bed porosity and low total particle surface area for the trilobe packing structure give rise to the lowest pressure drop of 27.8 Pa/m,while the internal voids cutting mode provides the excellent heat transfer capacity for the Raschig ring packing structure and the highest ethylene conversion and thereby the highest bed temperature rise of 25.1 K for the four-hole cylinder packing *** on these analyses,changing the packing style to the bottom-up Raschig ring-four hole cylinder packing structure would be a good strategy for the effectively lowered reactor temperature rise by 4.8 K together with the slightly reduced ethylene conversion.

关键词： Ethylene oxidation particle shape Packing style Heat transfer

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Theoretical studies on particle shape classification based on simultaneous small forward angle light scattering and aerodynamic sizing

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Chinese Physics B 2016年第3期25卷 178-184页

作者：张金碧丁蕾王颖萍张莉吴金雷郑海洋方黎 Laboratory of Environmental Spectroscopy Anhui Institute of Optics and Fine MechanicsChinese Academy of SciencesHefei 230031China University of Chinese Academy of Sciences Beijing 100049China

particle shape contributes to understanding the physical and chemical processes of the atmosphere and better ascer- taining the origins and chemical compositions of the particles. The particle shape can be classified by the aspect ratio. which can be estimated through the asymmetry factor measured with angularly resolved light scattering. An experimental method of obtaining the asymmetry factor based on simultaneous small forward angle light scattering and aerodynamic size measurements is described briefly. The near forward scattering intensity signals of three detectors in the azimuthal angles at 120° offset are calculated using the methods of T-matrix and discrete dipole approximation. Prolate spheroid particles with different aspect ratios are used as the shape models with the assumption that the symmetry axis is parallel to the flow axis and perpendicular to the incident light. The relations between the asymmetry factor and the optical size and aerodynamic size at various equivalent sizes, refractive indices, and mass densities are discussed in this paper. The numerically calculated results indicate that an elongated particle may be classified at diameter larger than 1.0 μm, and may not be distinguished from a sphere at diameter less than 0.5 μm. It is estimated that the lowest detected aspect ratio is around 1.5： I in consideration of the experimental errors.

关键词： particle shape aspect ratio asymmetry factor light scattering

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Investigation of micro-scale shear response of sand–rubber granule mixture in terms of particle shape and grain scale deformability effects

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Particuology 2024年第7期90卷 452-469页

作者： Abdulmuttalip Ari Suat Akbulut Department of Civil Engineering Yildiz Technical UniversityIstanbul34220Turkey

In this study,the effects of particle shape of rigid sand and soft rubber materials on macro-scale shear response were reasoned based on micro-scale *** this purpose,first,the shape properties of three different sand and two different rubber samples were quantified using image processing techniques,and the contact model parameters were calibrated through physical *** direct shear test was simulated in a two-dimensional discrete element software with realistic particle *** soft nature of rubber particles was reflected using body-centered cubic packing with a linear-parallel bond contact *** a result,coordination number,distribution of contact forces(i.e.,strong contact,and fabric anisotropy),and contact sliding were derived by the numerical *** has been observed that the particle shape leads to distinctive micro-scale responses due to the variations in the stiffness of the contacts.

关键词： particle shape Sand Rubber Shear response Micro-scale response Discrete element method

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Shear behaviours of cohesionless mixed soils using the DEM:The influence of coarse particle shape

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Particuology 2021年第2期19卷 151-165页

作者： Yangui Zhu Jian Gong Zhihong Nie School of Civil Engineering Central South UniversityChangsha 410075China

The coarse particles in mixed soils can be cobbles or gravels,with the main difference being their roundness(an indicator describing particle shape characteristics at an intermediate scale).The influence of coarse particle shape(i.e.,roundness)on the macroscopic and microscopic shear behaviours of cohesionless mixed soils with various fines contents(FCs)was investigated via the discrete element method in this *** shapes of coarse particles were formed using the rotation-invariant spherical harmonic method proposed by previous *** equation was proposed to predict the initial void ratios of samples in this study.A decrease in the roundness of coarse particles can increase the peak friction angle(FC≤40%)and critical friction angle(FC≤30%).As the roundness of coarse particles decreases,the peak dilatancy angle initially increases and then decreases(FC≤20%).Furthermore,it was found that the roundness of coarse particles hardly affects the classification of cohesionless mixed soils,as determined by probing the percentage contributions of coarse-coarse,coarse-fine,and fine-fine *** cohesionless mixed soils change from an underfilled structure to an interactive-underfilled structure at the critical state,the main forms of coarse-coarse contacts were ***,the force-fabric anisotropy mechanisms of the influences of the roundness and rolling resistance coefficient of coarse particles on the shear strengths of cohesionless mixed soils were found to be different.

关键词： Cohesionless mixed soils particle shape Roundness Shear behaviours Discrete element method

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Effect of particle shape on Dust Shortwave Direct Radiative Forcing Calculations Based on MODIS Observations for a Case Study

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Advances in Atmospheric Sciences 2015年第9期32卷 1266-1276页

作者： FENG Qian CUI Songxue ZHAO Wei National Satellite Ocean Application Service

Assuming spheroidal and spherical particle shapes for mineral dust aerosols,the effect of particle shape on dust aerosol optical depth retrievals,and subsequently on instantaneous shortwave direct radiative forcing（SWDRF） at the top of the atmosphere（TOA）,is assessed based on Moderate Resolution Imaging Spectroradiometer（MODIS） data for a case ***,a simplified aerosol retrieval algorithm based on the principle of the Deep Blue aerosol retrieval method is employed to retrieve dust aerosol optical depths,and the Fu–Liou radiative transfer model is used to derive the instantaneous SWDRF of dust at the TOA for cloud-free *** considering the effect of particle shape on dust aerosol optical depth retrievals,the effect of particle shape on the scattering properties of dust aerosols（e.g.,extinction efficiency,single scattering albedo and asymmetry factor） is negligible,which can lead to a relative difference of at most 5% for the SWDRF at the ***,the effect of particle shape on the SWDRF cannot be neglected provided that the effect of particle shape on dust aerosol optical depth retrievals is also taken into account for SWDRF *** corresponding results in an instantaneous case study show that the relative differences of the SWDRF at the TOA between spheroids and spheres depend critically on the scattering angles at which dust aerosol optical depths are retrieved,and can be up to 40% for low dust-loading conditions.

关键词： dust particle shape aerosol optical depth direct radiative forcing

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Effect of particle shape on Catalyst Deactivation during 2-Butene and Isobutane Alkylation of Liquid Phase in Fixed-Bed Reactor Using particle-Resolved CFD Simulation

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China Petroleum Processing & Petrochemical Technology 2022年第4期24卷 139-150页

作者： Zhang Sizhen Zhu Zhenxing Xin Feng Chu Menghan School of Chemical Engineering and Technology Tianjin UniversityTianjin 300350China SINOPEC Research Institute of Petroleum Processing Co. Ltd.Beijing 100083China

How catalyst shape affects its deactivation is a crucial issue for quickly decaying catalysts such as zeolite in 2-butene and isobutane *** this work,steady simulations are used to determine the temperature and species distribution in fixed beds filled with particles of four ***,unsteady simulations are used to study the deactivation behavior of the catalysts based on the steady simulation *** describe the deactivation rate and type of catalyst deactivation by defining a local internal diffusivity,which is affected by catalytic *** results reveal that the internal diffusion distance of the catalyst determines the deactivation rate,whereas the local internal diffusivity determines its deactivation type.

关键词： alkylation catalyst deactivation particle shape fixed bed particle-resolved CFD

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particle shape Control of Crushed Stone by Autogenous Grinding Using a Stirred Mill

Particle Shape Control of Crushed Stone by Autogenous Grindi...

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第八届东亚资源再生技术国际会议

作者： N.Kotake Y.Miyano Y.Kanda T.Ishikawa T.Itabashi Department of Chemistry and Chemical Engineering Yamagata University 4-3-16 Jonan Yonezawa-shi Yamagata992-8510 Japan Department of Chemistry and Chemical Engineering Yamagata University 4-3-16 Jonan Yonezawa-shi Yamagata992-8510 Japan Department of Chemistry and Chemical Engineering Yamagata University 4-3-16 Jonan Yonezawa-shi Yamagata992-8510 Japan Mistui Mining Co. LTD. 1 Koh-machi Tochigi-shi Tochigi 328-8503 Japan Mistui Mining Co. LTD. 1 Koh-machi Tochigi-shi Tochigi 328-8503 Japan

＜正＞A demand for the aggregates is increasing in the field of civil industry and architectural industry and so on. In these industries, the particle size and shape of aggregates are important factors and especially spherical or rounded particles are desired. In Japan, crushed stone is widely used as the aggregate material for the pavement or the construction. In this study based on the frictional action of material each other, an autogenous grinding of crushed stone was performed in order to eliminate squarish particles and get rounded ones for better aggregate materials. The experimental apparatus is a stirred mill with 4 impellers and the mill is made of stainless steel. The feed size and the feed mass of crushed stone were constant respectively. The particle shape was measured in the particle size range of 20 mm - 2.36 mm, and was evaluated by the shape index（= diameter of circumcircle / thickness） and the circularity（= perimeter of circle of equal projected area / perimeter of particle）. As a result, a decrease in the shape index and an increase in the circularity of crushed stone were observed with increasing grinding time. Then, the shape index and the circularity had the limit value for the long time grinding. The tendencies in these variations were not changed by the measuring size. The limit values of the shape index and the circularity increased with decreasing measuring size respectively.

关键词： Autogenous grinding Stirred mill Crushed stone particle shape

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Catalyst particle shapes and pore structure engineering for hydrodesulfurization and hydrodenitrogenation reactions

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Frontiers of Chemical Science and Engineering 2022年第6期16卷 897-908页

作者： Yao Shi Zhao Li Changfeng Yang Zhanlin Yang Zhenhui Lv Chong Peng Bao-Lian Su Weikang Yuan Xinggui Zhou Xuezhi Duan State Key Laboratory of Chemical Engineering East China University of Science and TechnologyShanghai 200237China Dalian Research Institute of Petroleum and Petrochemicals SINOPECDalian 116045China Laboratory of Inorganic Materials Chemistry University of NamurB-5000 NamurBelgium

Catalyst particle shapes and pore structure engineering are crucial for alleviating internal diffusion limitations in the hydrodesulfiirization(HDS)/hydrodeni-trogenation(HDN)of gas *** effects of catalyst particle shapes(sphere,cylinder,trilobe,and tetralobe)and pore structures(pore diameter and porosity)on HDS/HDN performance at the particle scale are investigated via mathematical *** relationship between particle shape and effectiveness factor is first established,and the specific surface areas of different catalyst particles show a positive correlation with the average HDS/HDN reaction *** catalyst particle shapes primarily alter the average HDS/HDN reaction rate to adjust the HDS/HDN effectiveness *** optimal average HDS/HDN reaction rate exists as the catalyst pore diameter and porosity increase,and this optimum value indicates a tradeoff between diffusion and *** contrast to catalyst particle shapes,the catalyst pore diameter and the porosity of catalyst particles primarily alter the surface HDS/HDN reaction rate to adjust the HDS/HDN effectiveness *** study provides insights into the engineering of catalyst particle shapes and pore structures for improving HDS/HDN catalyst particle efficiency.

关键词： hydrodesulfiirization hydrodenitrogenation particle shape pore structure

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UNSTEADY NATURAL CONVECTIVE BOUNDARY LAYER FLOW AND HEAT TRANSFER OF FRACTIONAL SECOND-GRADE NANOFLUIDS WITH DIFFERENT particle shapeS

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Annals of Applied Mathematics 2020年第3期36卷 257-269页

作者： Ming Shen Yuhang Wu Mengchen Zhang College of Mathematics and Computer Science Fuzhou UniversityFuzhou 350108FujianPR China

The present study is concerned with unsteady natural convective boundary layer flow and heat transfer of fractional second-grade nanofuids for different particle *** boundary layer governing equations are formulated with time fractional derivatives in the momentum *** governing boundary layer equations of continuity,momentum and energy are reduced by dimensionless *** solutions of the momentum and energy equations are obtained by the finite difference method combined with *** quantites of physical interest are graphically presented and discussed in *** is found that particle shape,fractional derivative parameter and the Grashof number have profound influences on the the flow and heat transfer.

关键词： second-grade nanofluid heat transfer Caputo derivative particle shape

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