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A Eulerian population balance/Monte Carlo approach for simulating laminar aluminum dust flames

Particuology 2024年第5期88卷 323-343页

作者： Fabian Sewerin Jannis Finke Emmy Noether Group for Dispersed Multiphase Flows Chair of Mechanical Process EngineeringOtto-von-Guericke-Universität MagdeburgUniversitätsplatz 239106 MagdeburgGermany

Recently,metal powders have been conceptualized as carbon-free recyclable energy carriers that may form a cornerstone of a sustainable energy *** combustion of metal dusts in oxidizing atmospheres is exothermal and yields oxide particles that could,potentially,be retrieved and,subsequently,recharged by conversion to pure metals using green primary energy *** a step towards a predictive tool for designing metal dust combustors,we present a fully Eulerian modelling approach for laminar particle-laden reactive flows that is,conceptually,based on a population balance description of the dispersed particles and relies on a stochastic Eulerian solution *** the population balance equation(PBE)is formulated for the number-weighted distribution of characteristic properties among all particles near a spatial location,it is kinetically informed by the rates at which mass,momentum and heat are exchanged between the carrier gas and the particulate phase on the single particle *** the scope of the Eulerian Monte Carlo solution scheme,the property distribution is discretely represented in terms of the total number density and a finite number of property samples and the computational work is channelled towards the Eulerian estimation of mean particle *** the case of reactive aluminum particles,we combine a kinetic description of the gas-particle heat and mass transfer with a transport-limited continuum formulation to obtain rate expressions that are valid across the entire particle size range from the free molecular through the continuum *** velocity,the particle properties include only the particle mass,temperature and oxide mass *** set of thermochemical degrees of freedom is retained also as phase transitions due to melting occur,drawing on a smooth blend of the solid and liquid thermodynamic and material *** particle-level formulation encompasses aluminum evaporation,surface oxidation,scavenging of oxi

关键词： Metal dust combustion Aluminum population balance Eulerian Monte Carlo

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VERIFICATION OF SMOM AND QMOM population balance MODELING IN CFD CODE USING ANALYTICAL SOLUTIONS FOR BATCH PARTICULATE PROCESSES

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China Particuology 2006年第5期4卷 243-249页

作者： Terry A.Ring Department of Chemical Engineering University of Utah Salt Lake City UT 84112Fluent Inc. 10 Cavendish Court Lebanon NH 03766

For many processes of industrial significance, due to the strong coupling between particle interactions and fluid dynamics, the population balance must be solved as part of a computational fluid dynamics （CFD） simulation. In this work, a CFD based population balance model is tested using a batch crystallization reactor. In this CFD model, the population balance is solved by the standard method of moments （SMOM） and the quadrature method of moments （QMOM）. The results of these simulations are compared to analytical solutions for the population balance in a batch tank where 1） nucleation, 2） growth, 3） aggregation, and 4） breakage are taking place separately. The results of these comparisons show that the first 6 moments of the population balance are accurately predicted for nucleation, growth, aggregation and breakage at all times.

关键词： population balance computational fluid dynamics particle process modeling

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COMPARISON OF ANALYTICAL SOLUTIONS FOR CMSMPR CRYSTALLIZER WITH QMOM population balance MODELING IN FLUENT

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China Particuology 2005年第4期3卷 213-218页

作者： Bin Wan Terry A. Ring Kumar M. Dhanasekharan Jayanta Sanyal Department of Chemical Engineering University of Utah Salt Lake City UT 84112 Fluent Inc. 10 Cavendish CourtLebanon NH 03766

Fluent version 6.2 computational fluid dynamics environment has been enhanced with a population balance capability that operates in conjunction with its multiphase calculations to predict the particle size distribution within the flow field. The population balance is solved by the quadrature method of moments （QMOM）. Fluent＇s prediction capabilities are tested by using a 2-dimensional analogy of a constantly stirred tank reactor with a fluid flow compartment that mixes the fluid quickly and efficiently using wall movement and has a feed stream and a product stream. The results of these Fluent simulations using QMOM population balance solver are compared to steady state analytical solutions for the population balance in a stirred tank where 1） growth, 2） aggregation, and 3） breakage, take place separately and 4） combined nucleation and growth and 5） combined nucleation, growth and aggregation take place. The results of these comparisons show that the moments of the population balance are accurately predicted for nucleation, growth, aggregation and breakage when the flow field is turbulent. With laminar flow the mixing is not ideal and as a result the steady state well mixed solutions are not accurately simulated.

关键词： population balance particle size distribution computational fluid dynamics crystallization modeling

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Biomass Vapogasification in Fluidized Bed： Modelling of Char population balance and Experimental Validation

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Journal of Chemistry and Chemical Engineering 2010年第12期4卷 38-51页

作者： Marc Detoumay Mehrdji Hemati Chemical Engineering Laboratory U.M.R. 5503 ENSIACET 4 all~e Emile Monso-BP 84234 31432 Toulouse Cedex 4 France

The article presents a population balance model by mass developed for studying char gasification by steam occuring in a fluidized bed. The model has been validated by comparison with existing theoretical and experimental cases. Its main goal is to have a better understanding on particles size distribution behaviour during operation of the fluidized bed, and in particular to be applied on the case of Fast Internally Circulating Fluidized Beds for char gasification. Results have shown that the initial properties of the fluidized bed particles （bed and size distribution） are almost not involved in the steady state obtained in continous operation, which is excusively dependent on the properties of the fed particles flow rate and size distribution, the withdrawal flow rate and the reaction properties. Morevoer, it has been proven that the steady state fluidized bed mass and size distribution may be theroretically controlled by an adequate choice of feeding and withdrawal flow rates.

关键词： population balance size distribution steam gasification biomass char particles.

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Influence of zone formation on stability of continuous fluidized bed layering granulation with external product classification

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Particuology 2015年第6期13卷 1-7页

作者： C. Dreyschultze C. Neugebauer S. Palis A. Buck E. Tsotsas S. Heinrich A. Kienle Otto yon Guericke University Universit~tsplatz 2 D-39106 Magdeburg Germany Max Planck Institute for Dynamics of Complex Technical Systems Sandtorstraabe 1 D-39106 Magdeburg Germanyc Hamburg University of Technology Denickestrae 15 D-21073 Hamburg Germany

Continuous fluidized bed layering granulation with external product classification and a sieve-mill cycle can show instability in the form of self-sustained nonlinear oscillations of the particle size distribution. In the present study, the stability and bifurcation analysis of this process is presented. The underlying process models explicitly account for compartmentalization of the fluidized bed into a granulation and a drying zone, which is an important feature of many technical processes. Implications for plant operations are discussed with the help of stability diagrams as a function of zone size, residence time within different zones, the addition of external seeds and particular properties of the sieve-mill cycle.

关键词： Fluidized bed Granulation population balance Stability Bifurcation

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CFD-PBM coupled modeling of the liquid-liquid dispersion characteristics and structure optimization for Kenics static mixer

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Chinese Journal of Chemical Engineering 2024年第6期70卷 173-188页

作者： Junhai Deng Shilin Lan Juchang Wu Shenghua Du Weidong Liu Luchang Han Yefeng Zhou National&Local United Engineering Research Centre for Chemical Process Simulation and Intensification Chemical Process Simulation and Optimization Engineering Research Center of Ministry of EducationXiangtan UniversityXiangtan 411105China Hunan Haili Chemical Industry Company Limited Changsha 410000China

Kenics static mixers(KSM)are extensively used in industrial mixing-reaction processes by virtue of high mixing efficiency,low power homogenization and easy continuous *** liquid droplet size and its distribution and thus revealing the dispersion characteristics are of great significance for structural optimization and process intensification in the *** this work,a computational fluid dynamics-population balance model(CFD-PBM)coupled method is employed to systematically investigate the effects of operating conditions and structural parameters of KSM on droplet size and its distribution,to further reveal the liquid-liquid dispersion *** indicate that higher Reynolds numbers or higher dispersed phase volume fractions increase energy dissipation,reducing Sauter mean diameter(SMD)of dispersed phase droplets and with a shift in droplet size distribution(DSD)towards smaller *** aspect ratios,greater blade twist and assembly angles amplify shear rate,leading to smaller droplet size and a narrower DSD in the smaller *** degree of impact exerted by the aspect ratio is notably ***,mixing elements with different spin enhance shear and stretching *** to the same spin,SMD becomes 3.7-5.8 times smaller in the smaller size range with a significantly narrower *** into account the pressure drop and efficiency in a comprehensive manner,optimized structural parameters for the mixing element encompass an aspect ratio of 1-1.5,a blade twist angle of 180°,an assembly angle of 90°,and interlaced assembly of adjacent elements with different *** work provides vital theoretical underpinning and future reference for enhancing KSM performance.

关键词： CFD population balance Liquid-liquid dispersion Kenics static mixer

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Numerical investigation of turbulent bubbly wakes created by the ventilated partial cavity

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Science China(Physics,Mechanics & Astronomy) 2012年第2期55卷 297-304页

作者： XIANG Min ZHANG WeiHua CHEUNG S.C.P. TU JiYuan Institute of Aerospace and Material Engineering National University of Defense TechnologyChangsha 410073China School of Aerospace Mechanical and Manufacturing EngineeringRMIT UniversityVictoria 3083Australia

This paper presents a numerical study on the turbulent bubbly wakes created by the ventilated partial cavity.A semi-empirical approach is introduced to model the discrete interface of the ventilated cavity and its complex gas leakage rate induced by the local turbulent shear *** on the Eulerian-Eulerian two-fluid modeling framework,a population balance approach based on MUltiple-SIze-Group (MUSIG) model is incorporated to simulate the size evolution of the sheared off microbubbles and its complex interactions with the two-phase flow structure in the wake *** predictions at various axial locations downstream of the test body were in satisfactory agreement with the experimental *** captured bubbly wake structure illustrates that the bubbles may disperse as a twin-vortex tube driven by gravity *** predicted Sauter mean bubble diameter has confirmed the dominance of the coleascense process in the axial *** the bubbles develop downstream,the coleascense and breakup rate gradually reach balance,resulting in the stable bubble diameter.A close examination of the flow structures,gas void fraction distributions and the bubble size evolution provides valuable insights into the complex physical phenomenon induced by ventilated cavity.

关键词： ventilated cavity population balance bubbly wake computational fluid dynamics

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Numerical Simulation of Mixing in a Micro-well Scale Bioreactor by Computational Fluid Dynamics

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Chemical Research in Chinese Universities 2002年第2期18卷 113-116页

作者： Hu Zhang Sally Lamping Parviz Ayazi Shamlou Advanced Biochemical Engineering Centre University College LondonTorrington PlaceLondonWC1E 7JE

The introduction of the multi well plate miniaturisation technology with its associated automated dispensers, readers and integrated systems coupled with advances in life sciences has a propelling effect on the rate at which new potential drug molecules are discovered. The translation of these discoveries to real outcome now demands parallel approaches which allow large numbers of process options to be rapidly assessed. The engineering challenges in achieving this provide the motivation for the proposed work. In this work we used computational fluid dynamics(CFD) analysis to study flow conditions in a gas liquid contactor which has the potential to be used as a fermenter on a multi well format. The bioreactor had a working volume of 6 5 mL with the major dimensions equal to those of a single well of a 24 well plate. The 6 5 mL bioreactor was mechanically agitated and aerated by a single sparger placed beneath the bottom impeller. Detailed numerical procedure for solving the governing flow equations is given. The CFD results are combined with population balance equations to establish the size of the bubbles and their distribution in the bioreactor. Power curves with and without aeration are provided based on the simulated results.

关键词： CFD Numerical simulation Fermenter Snapshot method Two fluid population balance

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