Download or read book CFD Studies of Reactive Flow with Thermal and Mass Diffusional Effects in a Supercritical Packed Bed Catalytic Reactor written by Samuel J. Mekala and published by . This book was released on 2018 with total page 213 pages. Available in PDF, EPUB and Kindle. Book excerpt: Packed bed reactors are widely used in various chemical processes. Fundamental understanding of the heat and mass transfer phenomena in the packed beds is essential for better modelling of these processes. Theoretical models used to describe the flow in packed beds generally assume an effectively homogeneous systems ignoring the complexities of flow in the void spaces of the packed beds. These details may however be influencing significantly the various phenomena in the system. To enhance this understanding, Computational Fluid Dynamics (CFD) is used to obtain detailed flow, temperature and concentration profiles in packed bed with multiple species undergoing heat and mass transfer with accompanying reaction in a heterogeneous catalytic reactor model. CFD is a simulation tool that through solving of momentum, mass and energy balances around complex geometries gives advanced view of fluid flow and transport mechanisms in the catalytic reactor. In this thesis work, fluid flow and heat and mass transfer phenomena in packed beds is solved using CFD codes, developing a modelling strategy to design heterogeneous reaction packed bed equipment. Supercritical transesterification reaction process, for which experimental data was available from earlier experimental work was available was taken as a reference processes for simulation models. Due to the complexity of this process which involves various transport phenomena, and extreme operating conditions, each of the transfer process occurring in the packed bed is studied distinctly. A state-of-the art and a literature review is presented for CFD applications in packed beds, supercritical fluids and transesterification reaction. The governing equations and accompanying complementary models used in the simulations are presented. Physical properties of the reaction components methanol, triolein, diglyceride, mono-glyceride, fatty acid methyl esters, and glycerol at supercritical conditions are estimated. A geometrical model of heterogeneous catalytic reactor, which is a cylindrical tube filled with cylindrical particles arranged randomly, is developed representing a laboratory pilot unit. A 120-degree segment of packed bed tube is generated and validated against a complete wall-segment bed. Mesh influence over the flow is checked for different mesh refinement and a mesh of optimal refinement, independent of the mesh is selected for further study. As the packed bed is heated from the walls, wall-to-fluid heat transfer in packed beds is analysed, and CFD obtained results are used to review the radial flow effects in packed bed flow. The results are also related with empirical correlations analysing comparable trends. Particle-to-fluid mass transfer in packed beds is also studied with the triolein diffusion from particles to analyse the diffusional effects in the bed. For an analogous energy transfer, particle-to-fluid heat transfer is also studied. CFD obtained results are compared against previously published experimental data/empirical correlations. Mixed (free + forced) convection in packed beds at high pressure is also studied. Numerical results obtained are presented and compared against experimental data on mass transfer for supercritical extraction. Applicability of available reaction kinetics for transesterification reaction is studied. Packed bed models are prepared for one-step irreversible and three-step reversible reaction kinetics, for different temperatures and space-times. Numerical results are compared against experimental results, and flow, concentration and conversion profiles are obtained and analysed. Effects of the two kinetic models is studied for different temperatures and space-times.
Download or read book Computational Flow Modeling for Chemical Reactor Engineering written by Vivek V. Ranade and published by Academic Press. This book was released on 2002 with total page 476 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book relates the individual aspects of chemical reactor engineering and computational flow modeling in a coherent way to explain the potential of computational flow modeling for reactor engineering research and practice.
Download or read book CFD Simulation and Experiment of Catalyst Deactivation and Heat Transfer in a Low N Fixed bed Reactor written by Mohsen Behnam and published by . This book was released on 2011 with total page 358 pages. Available in PDF, EPUB and Kindle. Book excerpt: Abstract: Modeling of fluid flow, heat transfer and reaction in fixed beds is an essential part of their design. This is especially critical for highly endothermic reactions in low tube-to-particle diameter ratio (N) tubes, such as methane steam reforming (MSR) and alkane dehydrogenation as two important commercial reactions. The modeling of fixed bed reaction is available in literatures with lots of assumptions. However, there is a need for implementing the reaction conditions with diffusion aspects on a real fixed bed reactor without assuming any pseudo conditions. Computational fluid dynamics (CFD) has been found as a suitable tool by many researchers to simulate fixed beds. CFD can simulate complex geometry of randomly-packed tubes, and provides us with more fundamental understanding of the transport and reaction phenomena in reactor tubes. CFD can be used to obtain detailed three-dimensional velocity, species and temperature fields that are needed to improve engineering approaches. Previously, the geometry of 120-degree wall segment (WS) of the whole reactor tube has been studied in our group. Previous works have introduced the coupling of gas flow and resolved species and temperature gradients inside pellets by CFD for methane steam reforming (MSR) and propane dehydrogenation (PDH) without considering deactivation. The deactivation of catalysts due to carbon formation is an important problem in industry, such as steam reforming and the catalytic dehydrogenation of alkanes, which are both strongly endothermic reactions. Many researches were carried out to study the effect of carbon formation and catalyst deactivation on the reactor performance. The local carbon deposition on catalysts can cause particle breakage and strongly decrease reaction rates. Catalyst deactivation in heated tubes removes the heat sink and can result in local hot spots that weaken the reactor tube. This is particularly a problem for a low tube-to-particle diameter ratio fixed bed reactor. A 3D resolved CFD model simulation was used to study the local details of carbon deposition in which the reactions and deactivation take place inside the catalytic solid particles. CFD simulations of flow, heat transfer, diffusion and reaction were carried out using the commercial CFD code FLUENT/ANSYS 6.3 in a 3D 120-degree periodic wall segment with N=4. The mesh used boundary layer prism cells at both the inside and outside particle surfaces and at the tube wall. These reactions were represented in the solid particles using user-defined scalars to mimic species transport and reaction, with user-defined functions supplying reaction rates. Diffusion in the particles was modeled by Fick's law using an effective diffusivity, given by Hite and Jackson's approximation of the Dusty Gas Model. The transient developments of particle internal gradients and carbon accumulation have been studied for the early stages of deactivation. Carbon concentration is initially strongest close to the surface and in the high temperature regions of the catalysts and affected by the wall heat flux. Deactivation of the endothermic reactions causes a slow increase in the average catalyst temperature. The second stage of the research was the verification of our CFD reaction model with experimental data under reacting conditions. The highly endothermic commercial methane steam reforming (MSR) reaction was studied experimentally in a fixed bed reactor. The temperature contributions inside catalyst particles were measured. The MSR reaction showed strong effects on the temperature profile along the reactor. Then, a CFD model was used to predict temperature profiles under MSR reaction conditions. Comparison of CFD and experimental data showed very good qualitative as well as quantitative agreement for temperature inside catalyst particles at different inlet gas temperatures. The last stage was to develop a fundamental energy equation without introducing new adjustable parameters to study heat transfer in fixed beds. In the past, many researchers have been carried out to simulate the heat transfer in fixed bed reactors by using k[subscript r] (effective thermal conductivity) and h[subscript w] (heat transfer coefficient). But the classical model with k[subscript r] and h[subscript w] cannot give a correct T(r) near tube wall, where deactivation is strongest. Therefore we need a better model which can represent the near wall heat transfer more accurate. CFD modeling was used to develop pseudo-continuum model for T(r) using V[subscript r] (r, z) and V[subscript z] (r). To get better temperature at the wall vicinity close to the physical reality. In this model radial thermal conductivity was obtained from Zehner-Schlünder model. The convection heat transfer was calculated in the 2D flow fluid from the CFD run. Results were obtained for Reynolds numbers in the range 240-?1900. The accuracy of the new model has been validated by analytical solution. The temperature calculated by the new velocity field pseudohomogenous energy equation showed reasonable quantitative agreement with values predicted by the CFD model.
Download or read book Computational Fluid Dynamics for Engineers written by Bengt Andersson and published by Cambridge University Press. This book was released on 2011-12-22 with total page 203 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational fluid dynamics, CFD, has become an indispensable tool for many engineers. This book gives an introduction to CFD simulations of turbulence, mixing, reaction, combustion and multiphase flows. The emphasis on understanding the physics of these flows helps the engineer to select appropriate models to obtain reliable simulations. Besides presenting the equations involved, the basics and limitations of the models are explained and discussed. The book combined with tutorials, project and power-point lecture notes (all available for download) forms a complete course. The reader is given hands-on experience of drawing, meshing and simulation. The tutorials cover flow and reactions inside a porous catalyst, combustion in turbulent non-premixed flow, and multiphase simulation of evaporation spray respectively. The project deals with design of an industrial-scale selective catalytic reduction process and allows the reader to explore various design improvements and apply best practice guidelines in the CFD simulations.
Download or read book Computational Fluid Dynamics CFD of Chemical Processes written by Young-Il Lim and published by MDPI. This book was released on 2021-02-22 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this Special Issue, one review paper highlights the necessity of multiscale CFD, coupling micro- and macro-scales, for exchanging information at the interface of the two scales. Four research papers investigate the hydrodynamics, heat transfer, and chemical reactions of various processes using Eulerian CFD modeling. CFD models are attractive for industrial applications. However, substantial efforts in physical modeling and numerical implementation are still required before their widespread implementation.
Download or read book CFD Applications in Nuclear Engineering written by Wenxi Tian and published by Frontiers Media SA. This book was released on 2023-08-21 with total page 219 pages. Available in PDF, EPUB and Kindle. Book excerpt: High fidelity nuclear reactor thermal hydraulic simulations are a hot research topic in the development of nuclear engineering technology. The three-dimensional Computational Fluid Dynamics (CFD) and Computational Multi-phase Fluid Dynamics (CMFD) methods have attracted significant attention in predicting single-phase and multi-phase flows under steady-state or transient scenarios in the field of nuclear reactor engineering. Compared with three-dimensional thermal hydraulic methods, the traditional one-dimensional system analysis method contains inherent defects in the required accuracy and spatial resolution for a number of important nuclear reactor thermal-hydraulic phenomena. At present the CFD method has been widely adopted in the nuclear industry, across both light water reactors and liquid metal cooled fast reactors, providing an effective solution for complex issues of thermal hydraulic analysis. However, the CFD method employs empirical models for turbulence simulation, heat transfer, multi-phase interaction and chemical reactions. Such models must be validated before they can be used with confidence in nuclear reactor applications. In addition, user practice guidelines play a critical role in achieving reliable results from CFD simulations.
Download or read book Advances of Computational Fluid Dynamics in Nuclear Reactor Design and Safety Assessment written by Jyeshtharaj Joshi and published by Woodhead Publishing. This book was released on 2019-06-11 with total page 888 pages. Available in PDF, EPUB and Kindle. Book excerpt: Advances of Computational Fluid Dynamics in Nuclear Reactor Design and Safety Assessment presents the latest computational fluid dynamic technologies. It includes an evaluation of safety systems for reactors using CFD and their design, the modeling of Severe Accident Phenomena Using CFD, Model Development for Two-phase Flows, and Applications for Sodium and Molten Salt Reactor Designs. Editors Joshi and Nayak have an invaluable wealth of experience that enables them to comment on the development of CFD models, the technologies currently in practice, and the future of CFD in nuclear reactors. Readers will find a thematic discussion on each aspect of CFD applications for the design and safety assessment of Gen II to Gen IV reactor concepts that will help them develop cost reduction strategies for nuclear power plants.
Download or read book Coupled CFD DEM Modeling written by Hamid Reza Norouzi and published by John Wiley & Sons. This book was released on 2016-09-14 with total page 432 pages. Available in PDF, EPUB and Kindle. Book excerpt: Discusses the CFD-DEM method of modeling which combines both the Discrete Element Method and Computational Fluid Dynamics to simulate fluid-particle interactions. Deals with both theoretical and practical concepts of CFD-DEM, its numerical implementation accompanied by a hands-on numerical code in FORTRAN Gives examples of industrial applications
Download or read book Advanced Reactor Modeling with MATLAB written by Riccardo Tesser and published by Walter de Gruyter GmbH & Co KG. This book was released on 2020-12-07 with total page 263 pages. Available in PDF, EPUB and Kindle. Book excerpt: Offers the reader a modern approach to reactor description and modelling. Using the widely applied numerical language MATLAB, it provides the reader with categorized groups of general code for a wide variety of chemical reactors. Being designed as a tool for researchers and professionals, the code can easily be extended and adapted by the reader to their own specific problems.
Download or read book CFD Studies of Wall region Fluid Flow and Heat Transfer in a Fixed Bed Reactor written by Michiel Nijemeisland and published by . This book was released on 1998 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book CFD Modeling of Complex Chemical Processes written by Li Xi and published by MDPI. This book was released on 2021-09-01 with total page 296 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational fluid dynamics (CFD), which uses numerical analysis to predict and model complex flow behaviors and transport processes, has become a mainstream tool in engineering process research and development. Complex chemical processes often involve coupling between dynamics at vastly different length and time scales, as well as coupling of different physical models. The multiscale and multiphysics nature of those problems calls for delicate modeling approaches. This book showcases recent contributions in this field, from the development of modeling methodology to its application in supporting the design, development, and optimization of engineering processes.
Download or read book CFD Techniques and Energy Applications written by Zied Driss and published by Springer. This book was released on 2018-02-22 with total page 199 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on CFD (Computational Fluid Dynamics) techniques and the recent developments and research works in energy applications. It is devoted to the publication of basic and applied studies broadly related to this area. The chapters present the development of numerical methods, computational techniques, and case studies in the energy applications. Also, they offer the fundamental knowledge for using CFD in energy applications through new technical approaches. Besides, they describe the CFD process steps and provide benefits and issues for using CFD analysis in understanding the flow complicated phenomena and its use in the design process. The best practices for reducing errors and uncertainties in the CFD analysis are further described. The book reveals not only the recent advances and future research trends of CFD Techniques but also provides the reader with valuable information about energy applications. It aims to provide the readers, such as engineers and PhD students, with the fundamentals of CFD prior to embarking on any real simulation project. Additionally, engineers supporting or being supported by CFD analysts can take advantage from the information of the book’s different chapters.
Download or read book Computational Fluid Dynamics Applied to Waste to Energy Processes written by Valter Silva and published by Butterworth-Heinemann. This book was released on 2020-06-16 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt: Computational Fluid Dynamics Applied to Waste-to-Energy Processes: A Hands-On Approach provides the key knowledge needed to perform CFD simulations using powerful commercial software tools. The book focuses on fluid mechanics, heat transfer and chemical reactions. To do so, the fundamentals of CFD are presented, with the entire workflow broken into manageable pieces that detail geometry preparation, meshing, problem setting, model implementation and post-processing actions. Pathways for process optimization using CFD integrated with Design of Experiments are also explored. The book's combined approach of theory, application and hands-on practice allows engineering graduate students, advanced undergraduates and industry practitioners to develop their own simulations. - Provides the skills needed to perform real-life simulation calculations through a combination of mathematical background and real-world examples, including step-by-step tutorials - Presents worked examples in complex processes as combustion or gasification involving fluid dynamics, heat and mass transfer, and complex chemistry sets
Download or read book Advances of CFD in Fluid Machinery Design written by Robin Elder and published by John Wiley & Sons. This book was released on 2003-02-07 with total page 258 pages. Available in PDF, EPUB and Kindle. Book excerpt: In the past Computational Fluid Dynamics (CFD) was confined to large organisations capable of developing and supporting their own codes. But recently there has been a rapid increase in the availability of reasonably priced commercial codes, and many more industrial organisations are now able to routinely use CFD. Advances of CFD in Fluid Machinery Design provide the perfect opportunity to find out what industry is doing and this book addresses how CFD is now being increasingly used in the design process, rather than as a post-design analysis tool. COMPLETE CONTENTS Trends in industrial use of CFD Challenges and methodologies in the design of axial flow fans for high-bypass-ratio, gas turbine engines using steady and unsteady CFD A three-dimensional inverse method based on pressure loading for the design of turbomachinery blades Application of CFD to the design and analysis of axial and centrifugal fans and compressors The design and performance of a transonic flow deswirling system – an application of current CFD design techniques tested against model and full-scale experiments Recent developments in unsteady flow modelling for turbomachinery aeroelasticity Computational investigation of flow in casing treatments for stall delay in axial flow fans Use of CFD for the three-dimensional hydrodynamic design of vertical diffuser pumps Recommendations to designers for CFD pump impeller and diffuser simulations Three dimensional CFD – a possibility to analyse piston pump flow dynamics CFD analysis of screw compressor performance Prediction of aerothermal phenomena in high-speed discstator systems Use of CFD in the design of a shaft seal for high-performance turbomachinery Users and potential users, of CFD for the design of fluid machinery, managers, designers, and researchers working in the field of ‘industrial flows’, will all find Advances of CFD in Fluid Machinery Design a valuable volume discussing state-of-the-art developments in CFD.
Download or read book Computational Fluid Dynamics CFD Simulation of a Gas Solid Fluidized Bed Residence Time Validation Study written by Baru Debtera and published by GRIN Verlag. This book was released on 2021-11-29 with total page 26 pages. Available in PDF, EPUB and Kindle. Book excerpt: Academic Paper from the year 2021 in the subject Physics - Mechanics, , language: English, abstract: In this study, numerical simulations of a gas-solid fluidized bed reactor involving a two-fluid Eulerian multiphase model and incorporating the Kinetic Theory of Granular Flow (KTGF) for the solids phase have been performed using a commercial Computational Fluid Dynamics (CFD) software. The fluidized bed setup consists of 1,5 m height and 0,2 m diameter in which a series of experiments were performed using Helium tracer to determine the Residence Time Distribution (RTD) at various normalized velocities i.e., with different degrees of gas-solids mixing. Both 2D and 3D simulations of the fluidized bed reactor are performed. The main purpose of this study is to understand the hydrodynamic behavior of a gas-solid fluidized bed reactor through a framework of Eulerian multiphase model and to analyze hydrodynamic behavior of the gas-solids mixing.
Download or read book CFD Techniques and Thermo Mechanics Applications written by Zied Driss and published by Springer. This book was released on 2018-02-05 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on CFD (Computational Fluid Dynamics) techniques and the recent developments and research works in thermo-mechanics applications. It is devoted to the publication of basic and applied studies broadly related to this area. The chapters present the development of numerical methods, computational techniques, and case studies in the thermo-mechanics applications. They offer the fundamental knowledge for using CFD in real thermo-mechanics applications and complex flow problems through new technical approaches. Also, they discuss the steps in the CFD process and provide benefits and issues when using the CFD analysis in understanding of complicated flow phenomena and its use in the design process. The best practices for reducing errors and uncertainties in CFD analysis are also discussed. The presented case studies and development approaches aim to provide the readers, such as engineers and PhD students, the fundamentals of CFD prior to embarking on any real simulation project. Additionally, engineers supporting or being supported by CFD analysts can benefit from this book.
Download or read book CFD Modeling and Simulation in Materials Processing 2016 written by Lifeng Zhang and published by John Wiley & Sons. This book was released on 2016-02-08 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: This collection explores computational fluid dynamics (CFD) modeling and simulation of engineering processes, with contributions from researchers and engineers involved in the modeling of multiscale and multiphase phenomena in material processing systems. The papers cover the following processes: Iron and Steelmaking (Tundish, Casting, Converter, Blast Furnace); Microstructure Evolution; Casting with External Field Interaction; and Smelting, Degassing, Ladle Processing, Mechanical Mixing, and Ingot Casting. The collection also covers applications of CFD to engineering processes, and demonstrates how CFD can help scientists and engineers to better understand the fundamentals of engineering processes.
