Cfd Simulations Of Particle Mixing In A Binary Fluidized Bed
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Cfd Simulations Of Particle Mixing In A Binary Fluidized Bed
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Author : Scott Cooper
language : en
Publisher:
Release Date : 2003
Cfd Simulations Of Particle Mixing In A Binary Fluidized Bed written by Scott Cooper and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with Chemical engineering categories.
Cfd Simulation Of Mixing And Segregation In A Tapered Fluidized Bed
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Author :
language : en
Publisher:
Release Date :
Cfd Simulation Of Mixing And Segregation In A Tapered Fluidized Bed written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on with categories.
Fluidization of different materials results either in a well-mixed or a segregated bed. Depending upon the operating conditions, smaller particles (floatsam) tend to rise to the bed, and larger particles (jetsam) tend to sink to the bottom of the bed. The tapered fluidized bed can be used to overcome certain draw backs of the gas-solid system because of the fact that a velocity gradient exists along the axial direction of the bed with increase in cross-sectional area. To study the dynamic characteristics of the homogenous mixture of regular and irregular particles several experiments have been carried out with varying compositions. The particle flow pattern and granule segregation in tapered fluidized bed have been studied by first fluidizing the beds of varying total mass and granule fractions and then defluidize them suddenly to freeze the composition, section the bed in layers, and determine the composition in each layer by sieving. A series of unsteady, three-fluid CFD simulations were performed using FLUENTTM 6.2. Simulation parameters viz. solution technique, grid, maximum packing fraction and operating conditions like gas velocity were each investigated for the relative effects on particle mixing and segregation. Good agreement of solid volume fraction profile was obtained between the experimental results and simulation results for regular particles.
Cfd Simulations Of Mixing Phenomena In A Binary Fluidized Bed
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Author : Scott A. Cooper
language : en
Publisher:
Release Date : 2003
Cfd Simulations Of Mixing Phenomena In A Binary Fluidized Bed written by Scott A. Cooper and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with Fluidization categories.
Cfd Simulation Of Particle Mixing In A Fluidized Bed
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Author : Deyi Kong
language : en
Publisher:
Release Date : 2013
Cfd Simulation Of Particle Mixing In A Fluidized Bed written by Deyi Kong and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2013 with Fluidized-bed combustion categories.
This project is to do the research of CFD simulation of particle mixing in a fluidized bed.Nowadays, fluidized bed is widely used in different kinds of industry, such aspower plant, petroleum industry and food processing industry. The objectives of this project are to study the mixing and segregation phenomena in a fluidized bed and to design distributors with low pressure drop operation. Fluidized beds suspend solid fuels on upward-blowing jets of air during the combustion process. The main characteristicof fluidized bed are pressure drop, fluid velocities, bubble size and bed heightComputational fluid dynamics (CFD) simulation is the method to study this project. Firstly, Ergun 6.2 software is used to study particle mixing and segregation phenomenaSecondly, 3D geometry of fluidized bed is drawn by using Solidworks 2012. Flowsimulation program is used to study pressure drop in the fluidized bed 3D drawing.Minimum fluidized velocity and operation point is found by using Ergun 6.2 softwarePressure drop is found by using Flow Simulation program. Compare with otherresearcher 's results these simulation results are accepted.
Computational Fluid Dynamics Simulation Of Fluidized Bed Polymerization Reactors
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Author : Rong Fan
language : en
Publisher:
Release Date : 2006
Computational Fluid Dynamics Simulation Of Fluidized Bed Polymerization Reactors written by Rong Fan and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.
In this research, a CFD algorithm for simulation of fluidized bed polymerization reactors is described. In order to properly model the evolution of a polydisperse solid phase, population balance equation (PBE) must be solved along with other transport equations. A novel approach - DQMOM is applied to polydisperse fluidized bed to simulate particle aggregation and breakage in the reactors. Two different aggregation and breakage kernels are tested and the performance of the DQMOM approximation with different numbers of nodes are compared. Results show that the approach is very effective in modeling solid segregation and elutriation and in tracking the evolution of the PSD, even though it requires only a small number of scalars. After successfully developed DQMOM-multi-fluid CFD model, the multi-fluid model is validated with available experiments and discrete particle simulation (DPS). The results show good agreements with experiment data for binary system and DPS results, and the simulations can describe segregation and mixing behavior in the fluidized bed. After the model development and validation, 2D and 3D simulations are conducted for a pilot-scale polymerization fluidized bed at operating conditions. Significant differences are observed between 2D and 3D simulations. The results shows that, for an industrial-scale fluidized bed, only 3D simulations are able to match the statics (bed height and pressure drop) and the dynamics (pressure power spectra) properties of the bed. The residence time for a polyethylene pilot reactor is on the order of hours, and the time scale for the fluid dynamics in the bed is on the seconds. It is impossible to run a three-dimensional simulation for hours using current CFD codes. Due to the time scale problem, a chemical reaction engineering model based on the age of particles is combined with multi-fluid model to initialize the fluidized bed to a steady state. Direct quadrature method of moments (DQMOM) is used to simulate the particle size distribution in the bed. The hot spots in the fluidized bed are also investigated using CFD simulations.
Role Of Mathematical Modeling In Advanced Power Generation Systems
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Author : Arijit Ganguli
language : en
Publisher: Frontiers Media SA
Release Date : 2023-11-13
Role Of Mathematical Modeling In Advanced Power Generation Systems written by Arijit Ganguli and has been published by Frontiers Media SA this book supported file pdf, txt, epub, kindle and other format this book has been release on 2023-11-13 with Technology & Engineering categories.
Energy demands throughout the globe has been increasing and the detrimental effects of carbon emissions on the environment by use of non-renewable resources has impacted life on the planet. The changing climate has caused an increase in natural calamities all over the globe. Many countries in the world have started to produce power using renewable resources like solar, biomass, wind energy, nuclear energy and green fuels. Though there are several technologies for power generation using the above sources, efficient design of these systems still needs lot of research. Mathematical modeling would play a vital role in design of state of the art technologies. Advanced nuclear power plants need special mention since they involve naturally driven safety systems where the complex phenomena of boiling, condensation and thermal stratification take place. These are difficult to model as there is more than one phase coupled with turbulence models, near wall phenomena, coalescence and break up, etc. Scaling up of such systems and their innovative design to reduce stratification requires the help of mathematical modeling. Other opportunities include Computational Fluid Dynamics (CFD) modeling for design of wind turbines for power generation using wind energy. Power generation from biomass involves use of gasifiers which has complex set of reactions and mostly two or three phases which are difficult to model using CFD at industrial scales.
Computational Fluid Dynamics Simulation Of Fluidized Bed Polymerization Reactors
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Author :
language : en
Publisher:
Release Date : 2006
Computational Fluid Dynamics Simulation Of Fluidized Bed Polymerization Reactors written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2006 with categories.
Fluidized beds (FB) reactors are widely used in the polymerization industry due to their superior heat- and mass-transfer characteristics. Nevertheless, problems associated with local overheating of polymer particles and excessive agglomeration leading to FB reactors defluidization still persist and limit the range of operating temperatures that can be safely achieved in plant-scale reactors. Many people have been worked on the modeling of FB polymerization reactors, and quite a few models are available in the open literature, such as the well-mixed model developed by McAuley, Talbot, and Harris (1994), the constant bubble size model (Choi and Ray, 1985) and the heterogeneous three phase model (Fernandes and Lona, 2002). Most these research works focus on the kinetic aspects, but from industrial viewpoint, the behavior of FB reactors should be modeled by considering the particle and fluid dynamics in the reactor. Computational fluid dynamics (CFD) is a powerful tool for understanding the effect of fluid dynamics on chemical reactor performance. For single-phase flows, CFD models for turbulent reacting flows are now well understood and routinely applied to investigate complex flows with detailed chemistry. For multiphase flows, the state-of-the-art in CFD models is changing rapidly and it is now possible to predict reasonably well the flow characteristics of gas-solid FB reactors with mono-dispersed, non-cohesive solids. This thesis is organized into seven chapters. In Chapter 2, an overview of fluidized bed polymerization reactors is given, and a simplified two-site kinetic mechanism are discussed. Some basic theories used in our work are given in detail in Chapter 3. First, the governing equations and other constitutive equations for the multi-fluid model are summarized, and the kinetic theory for describing the solid stress tensor is discussed. The detailed derivation of DQMOM for the population balance equation is given as the second section. In this section, monovariate population balance, bivariate population balance, aggregation and breakage equation and DQMOM-Multi-Fluid model are described. In the last section of Chapter 3, numerical methods involved in the multi-fluid model and time-splitting method are presented. Chapter 4 is based on a paper about application of DQMOM to polydisperse gas-solid fluidized beds. Results for a constant aggregation and breakage kernel and a kernel developed from kinetic theory are shown. The effect of the aggregation success factor and the fragment distribution function are investigated. Chapter 5 shows the work on validation of mixing and segregation phenomena in gas-solid fluidized beds with a binary mixture or a continuous size distribution. The simulation results are compared with available experiment data and discrete-particle simulation. Chapter 6 presents the project with Univation Technologies on CFD simulation of a Polyethylene pilot-scale FB reactor, The fluid dynamics, mass/heat transfer and particle size distribution are investigated through CFD simulation and validated with available experimental data. The conclusions of this study and future work are discussed in Chapter 7.
Multiphase Flow And Fluidization
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Author : Dimitri Gidaspow
language : en
Publisher: Elsevier
Release Date : 2012-12-02
Multiphase Flow And Fluidization written by Dimitri Gidaspow and has been published by Elsevier this book supported file pdf, txt, epub, kindle and other format this book has been release on 2012-12-02 with Science categories.
Useful as a reference for engineers in industry and as an advanced level text for graduate engineering students, Multiphase Flow and Fluidization takes the reader beyond the theoretical to demonstrate how multiphase flow equations can be used to provide applied, practical, predictive solutions to industrial fluidization problems. Written to help advance progress in the emerging science of multiphase flow, this book begins with the development of the conservation laws and moves on through kinetic theory, clarifying many physical concepts (such as particulate viscosity and solids pressure) and introducing the new dependent variable--the volume fraction of the dispersed phase. Exercises at the end of each chapterare provided for further study and lead into applications not covered in the text itself. Treats fluidization as a branch of transport phenomena Demonstrates how to do transient, multidimensional simulation of multiphase processes The first book to apply kinetic theory to flow of particulates Is the only book to discuss numerical stability of multiphase equations and whether or not such equations are well-posed Explains the origin of bubbles and the concept of critical granular flow Presents clearly written exercises at the end of each chapter to facilitate understanding and further study
Computational Techniques For Multiphase Flows
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Author : Guan Heng Yeoh
language : en
Publisher: Butterworth-Heinemann
Release Date : 2019-02-27
Computational Techniques For Multiphase Flows written by Guan Heng Yeoh and has been published by Butterworth-Heinemann this book supported file pdf, txt, epub, kindle and other format this book has been release on 2019-02-27 with Technology & Engineering categories.
Computational Techniques for Multiphase Flows, Second Edition, provides the latest research and theories covering the most popular multiphase flows The book begins with an overview of the state-of-the-art techniques for multiple numerical methods in handling multiphase flow, compares them, and finally highlights their strengths and weaknesses. In addition, it covers more straightforward, conventional theories and governing equations in early chapters, moving on to the more modern and complex computational models and tools later in the book. It is therefore accessible to those who may be new to the subject while also featuring topics of interest to the more experienced researcher. Mixed or multiphase flows of solid/liquid or solid/gas are commonly found in many industrial fields, and their behavior is complex and difficult to predict in many cases. The use of computational fluid dynamics (CFD) has emerged as a powerful tool for understanding fluid mechanics in multiphase reactors, which are widely used in the chemical, petroleum, mining, food, automotive, energy, aerospace and pharmaceutical industries. This revised edition is an ideal reference for scientists, MSc students and chemical and mechanical engineers in these areas. Includes updated chapters in addition to a brand-new section on granular flows. Features novel solution methods for multiphase flow, along with recent case studies. Explains how and when to use the featured technique and how to interpret the results and apply them to improving applications.
Modelling Batch Systems Using Population Balances
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Author :
language : en
Publisher: Bookboon
Release Date :
Modelling Batch Systems Using Population Balances written by and has been published by Bookboon this book supported file pdf, txt, epub, kindle and other format this book has been release on with categories.