检索结果-南通市图书馆

drag models for simulating gas–solid flow in the turbulent fluidization of FCC particles

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Particuology 2009年第4期7卷 269-277页

作者： Peng Li Xingying Lan Chunming Xu Gang Wang Chunxi Lu Jinsen Gao State Key Laboratory of Heavy Oil Processing China University of Petroleum Beijing 102249 China

This paper examines the suitability of various drag models for predicting the hydrodynamics of the turbulent fluidization of FCC particles on the Fluent V6.2 platform. The drag models included those of Syamlal-O＇Brien, Gidaspow, modified Syamlal-O＇Brien, and McKeen. Comparison between experimental data and simulated results showed that the Syamlal-O＇Brien, Gidaspow, and modified Syamlal-O＇Brien drag models highly overestimated gas-solid momentum exchange and could not predict the formation of dense phase in the fiuidized bed, while the McKeen drag model could not capture the dilute charac- teristics due to underestimation of drag force. The standard Gidaspow drag model was then modified by adopting the effective particle cluster diameter to account for particle clusters, which was, however, proved inapplicable for FCC particle turbulent fluidization. A four-zone drag model （dense phase, sub- dense phase, sub-dilute phase and dilute phase） was finally proposed to calculate the gas-solid exchange coefficient in the turbulent fluidization of FCC particles, and was validated by satisfactory agreement between prediction and experiment.

关键词： Turbulent fluidized bed FCC particle drag model CFD

Comparative analysis on gas–solid drag models in MFIX-DEM simulations of bubbling fluidized bed

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Chinese Journal of Chemical Engineering 2023年第12期64卷 64-75页

作者： Ruiyu Li Xiaole Huang Yuhao Wu Lingxiao Dong Srdjan Beloševic Aleksandar Milicevic Ivan Tomanovic Lei Deng Defu Che State Key Laboratory of Multiphase Flow in Power Engineering School of Energy and Power EngineeringXi’an Jiaotong UniversityXi’an 710049China Shunde Institute of Inspection Guangdong Institute of Special Equipment Inspection and ResearchFoshan 528300China Department of Thermal Engineering and Energy "VINCA" Institute of Nuclear Sciences–National Institute of the Republic of SerbiaUniversity of BelgradeMike Petrovica Alasa 12-1411351 VincaPO Box 52211001 BelgradeSerbia

In this study,the open-source software MFIX-DEM simulations of a bubbling fluidized bed(BFB)are applied to assess nine drag models according to experimental and direct numerical simulation(DNS)*** influence of superficial gas velocity on gas–solid flow is also *** results show that according to the distribution of time-averaged particle axial velocity in y direction,except for Wen–Yu and Tenneti–Garg–Subramaniam(TGS),other drag models are consistent with the experimental and DNS *** the TGS drag model,the layer-by-layer movement of particles is observed,which indicates the particle velocity is not correctly *** time domain and frequency domain analysis results of pressure drop of each drag model are *** is recommended to use the drag model derived from DNS or fine grid computational fluid dynamics–discrete element method(CFD-DEM)data first for CFD-DEM *** the investigated BFB,the superficial gas velocity less than 0.9 m·s^(-1) should be adopted to obtain normal hydrodynamics.

关键词： MFIX-DEM Simulation Dense flow Gas-solid Bubbling fluidized bed drag model

Particle-scale and sub-grid drag models coupled CFD for simulating the CO methanation in a CFB riser

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Particuology 2023年第12期83卷 178-193页

作者： Jiageng Li Yong Jia Bo Ouyang Bolun Yang Zheng-Hong Luo Zhong-Wen Liu Key Laboratory of Syngas Conversion of Shaanxi Province School of Chemistry&Chemical EngineeringShaanxi Normal UniversityXi'an710119China Department of Chemical Engineering School of Chemistry and Chemical EngineeringState Key Laboratory of Metal Matrix CompositesShanghai Jiao Tong UniversityShanghai200240China School of Chemical Engineering and Technology Xi'an Jiaotong UniversityXi'an710049China

The diffusion and chemical reactions inside the catalyst particles and the heterogeneous flow structure in the computational cells are key factors to affect the accuracy of the coarse-grid simulation in circulating fluidized bed(CFB)methanation *** this work,a particle-scale model is developed to calculate the effective reaction rate considering the transient diffusion and chemical reactions in the particle scale,i.e.,the scale of the single catalyst particle.A modified sub-grid drag model is proposed to consider the effects of the meso-scale and chemical reactions on the heterogeneous gas-solid interaction,where the meso-scale is between the single particle and the whole reactor and featured with the particle ***,a coupled model is developed by integrating the particle-scale and modified sub-grid drag models into ***,the coupled model is validated to achieve accurate predictions on the CO methanation process in a CFB ***,the coupled model can be performed with a coarse grid(∼58 times particle diameter)and a large time step(0.005 s)to accelerate the *** simply changing the reaction kinetics,different gas-solid catalytic reaction systems can be simulated by using the coupled model.

关键词： Computational fluid dynamics Circulating fluidized bed co methanation Particle-scale model drag model

Fluid-solid drag models selection for simulating wheat straw particle movement in anaerobic digester

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Agricultural and Biological Engineering 2023年第2期16卷 249-258页

作者： Yang Yang Hongguang Zhu College of Mechanical and Energy Engineering Tongji UniversityShanghai 201804China Institute of New Rural Development Tongji UniversityShanghai 201804China

Computational fluid dynamics(CFD)has been utilized to simulate the movements of wheat straw particles for agitator speed selection in full-scale wet *** research has found that the current drag model generally used for depicting the motion of spherical particles cannot match the movement behavior of wheat straw particles with their non-spherical *** this study,the sedimentation experiment and horizontal flow experiment of straw particles were determined using a V20-3D camera and a micro Particle Image Velocimetry(PIV)*** analyses of the experimental data and CFD simulation results,the prediction accuracies of the non-spherical drag models of Hölzer and Sommerfeld(HS),Kishore and Gu(KG),Haider and Levenspiel(HL),Richter and Nikrityuk(RN),and Fabio Dioguardi(FD)were evaluated by the motion of individual straw *** results showed that the KG model has a significant advantage over the other drag models,both simulating the particle settling velocities in a one dimensional settling experiment and simulating the predictable trajectory in a two-dimensional horizontal flow ***,the KG drag model was selected to simulate with CFD the wheat straw particle movement to select agitator ***,the realizable k-turbulence model was proven to be superior to the other turbulence models for simulating the continuous phase flow with CFD.

关键词： wheat straw particle drag model shape coefficient image analysis micro PIV measurement

Multi-scale numerical simulation of fluidized beds: model applicability assessment

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Particuology 2023年第9期80卷 11-41页

作者： Shuai Wang Chenshu Hu Kun Luo Jiahui Yu Jianren Fan State Key Laboratory of Clean Energy Utilization Zhejiang UniversityHangzhou310027China Shanghai Institute for Advanced Study of Zhejiang University Shanghai200120China

In the past few decades,multi-scale numerical methods have been developed to model dense gas-solidflow in fluidized beds with different resolutions,accuracies,and ***,ambiguity needsto be clarified in the multi-scale numerical simulation of fluidized beds:(i)the selection of the submodels,parameters,and numerical resolution;(ii)the multivariate coupling of operating conditions,bed configurations,polydispersity,and additional ***,a state-of-the-art review is performed to assess the applicability of multi-scale numerical methods in predicting dense gas-solid flow influidized beds at specific fluidization regimes(e.g.,bubbling fluidization region,fast fluidization regime),with a focus on the inter-particle collision models,inter-phase interaction models,collision parameters,and polydispersity effect.A mutual restriction exists between resolution and *** methods need more computational resources and thus are suitable for smaller-scale simulations to provide a database for closure ***-resolution methods require fewercomputational resources and thus underpin large-scale simulations to explore macro-scale *** validations need to be further conducted under multiple flow conditions and comprehensivemetrics(e.g.,velocity profiles at different heights,bubbles,or cluster characteristics)for furtherimprovement of the applicability of each numerical method.

关键词： Fluidized bed Dense gas-solid flows Multi-scale numerical methods drag model Inter-particle collisions

CFD-DEM simulation of Small-Scale Challenge Problem 1 with EMMS bubble-based structure-dependent drag coefficient

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Particuology 2021年第2期19卷 48-61页

作者： Musango Lungu John Siame Lloyd Mukosha Multiphase Flow Research Group Chemical Engineering DepartmentSchool of Mines and Mineral SciencesCopperbelt UniversityKitwe 10101Zambia

In this study,the energy minimization multi-scale(EMMS)/Bubbling model is coupled with the computational fluid dynamics/discrete element method(CFD-DEM)model via a structure-dependent drag coefficient to simulate the National Energy Technology Laboratory(NETL)small-scale challenge problem using the open-source multiphase flow code *** numerical predictions are compared against particle velocity measurements obtained from high-speed particle image velocimetry(HSPIV)and differential pressure *** drag-reduction effect of the EMMS bubble-based drag coefficient is observed to significantly improve predictions of the horizontal particle velocity and granular temperature when compared to several other drag coefficients tested;however,the vertical particle velocity and pressure fluctuation characteristic predictions are *** drag-reduction effect is characterized by a reduction in the sizes of slugs or voids,as identified through spectral decomposition of the pressure ***,this study shows great promise in employing drag coefficients,developed via multi-scale approaches(such as the EMMS paradigm),in CFD-DEM models.

关键词： CFD-DEM drag model EMMS/Bubbling model Fluidization Multi-scale

CFD Simulation of Particles Mixing and Segregation in a Rotary Coating Disk: Influence of drag models and Restitution Coefficient

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Open Journal of Applied Sciences 2022年第3期12卷 267-283页

作者： Salma Awad Nouh Ku Zilati Bt Ku Shaari Lau Kok Keong Shafirah Bt Samsuri Tigabwa Yosef Ahmed Department of Chemical Engineering Universiti Teknologi PETRONAS Seri Iskandar Malaysia

In this paper, the dynamics of a transverse plane of a rotary coating disk of a binary mixture system comprising sand and urea particles were simulated using the two-fluid model along with the kinetic theory of granular flow in Fluent 19.1. Although some parameters relating to the material properties and size of the rotary coating disk have been researched, the effects of both drag force and restitution coefficient on the flow characteristics have yet to be examined. Thus, this paper numerically examines the effect of the inclusion of drag models and particle-particle restitution coefficients on particle dynamics in a rotary disk operating in the rolling regime of the granular bed. Three particle-particle drag models were considered: the Schiller-Naumann, Syamlal-O’Brien, and Gidaspow. The Syamlal-O’Brien and Gidaspow models were both able to successfully simulate particle segregation in a perfect rolling regime, whereas the Schiller-Naumann drag model appeared to be unable to predict the segregation of the particles and the rolling flow regime under the assumed conditions. Four different values of the restitution coefficient were also investigated: 0.7, 0.8, 0.9, and 0.95. The higher restitution values of 0.9 and 0.95 were found to substantially affect flow characteristics, ensuring suitable rolling regime behaviour for the bed during the rotational movement. The lower restitution coefficients of 0.7 and 0.8, on the other hand, indicated that irregular velocity vectors could be obtained in the active region of the granular bed.

关键词： Rolling Mode drag model Restitution Coefficient CFD

Numerical study on hydrodynamics of gas-solids circulating fluidized bed with L-valve

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

颗粒学报:英文版 2023年第6期77卷 37-46页

作者： Hailun Ren Wenbin Li Liang Zeng Kunlei Liu Zhongli Tang Donghui Zhang Department of Chemical Engineering Tianjin Renai CollegeTianjin301636China School of Chemical Engineering and Technology Tianjin UniversityTianjin300072China Center for Applied Energy Research University of KentuckyLexingtonKY40511United States The Research Center of Chemical Engineering School of Chemical Engineering and TechnologyTianjin UniversityTianjin300072China

L-valve is often used as a non-mechanical valve for the circulation of solids in gas-solids fluidized bed(GSFB)due to its advantages in simple construction and easy *** information on solids circu-lation rate as well as the hydrodynamics performance of the CFB with L-valve is of great importance for its better control and *** paper proposes a Eulerian-Eulerian approach based numerical model integrating the computational fluid dynamics(CFD)with turbulent model,the kinetic theory of granular flow(KTGF)and the drag model,thus the solids circulation rate and the local phase velocity as well as solids volume fraction can be predicted *** this model,the hydrodynamics perfor-mance of the full loop GSCFB with a L-valve is analyzed in *** is found that the drag model affects the simulation significantly and the(energy minimization multiscale)EMMS method shows good per-formance in the full-loop simulation of GSCFB.

关键词： Gas-solids circulating fluidizedbed L-valve Computational fluid dynamics drag model Full-loop simulation

Effects of pressure on flow characteristics in a pressurized circulating fluidized bed

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Particuology 2021年第6期19卷 16-23页

作者： Pengfei Dong Qiuya Tu Haigang Wang Zhiping Zhu Institute of Engineering Thermophysics Chinese Academy of SciencesBeijing 10090China University of Chinese Academy of Sciences Beijing 100049China

The effects of operating pressure on the gas-solid flow characteristics in a pressurized circulating fluidized bed(CFB)gasification system were studied by experiment and *** operating pressure was found to increase the particle uniformity in the axial and radial *** and simulations both showed that as the operating pressure increased,the pressure drops along the riser height *** experimental pressure drops at the same locations decreased when the operating pressure increased,but the opposite trend was observed in the simulation results.A proper drag model must be developed for the accurate simulation of pressurized CFB operation,and the accuracy of electrical capacitance tomography(ECT)measurement and cross-correlation analysis should be improved for better prediction of the particle circulation flux.

关键词： Pressurized circulating fluidized bed Pressure effect drag model Uniformity