Computational Fluid Dynamics Modeling Of Sic Chemical Vapor Deposition
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Computational Fluid Dynamics Modeling Of Sic Chemical Vapor Deposition
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Author : Yingquan Song
language : en
Publisher:
Release Date : 2002
Computational Fluid Dynamics Modeling Of Sic Chemical Vapor Deposition written by Yingquan Song and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2002 with Chemical vapor deposition categories.
Computational fluid dynamics (CFD) modeling is used to simulate chemical vapor deposition (CVD) of silicon carbide (SiC), a wide-band gap semiconductor with a high breakdown field. The effects on SiC CVD of precursor concentration, flow rate, temperature, pressure, heat transfer and reactor geometry are investigated. Also demonstrates the possibilty of doping SiC with solid source vanadium during CVD growth of SiC epitaxial layers.
Design And Development Of A Silicon Carbide Chemical Vapor Deposition Reactor
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Author : Matthew T. Smith
language : en
Publisher:
Release Date : 2003
Design And Development Of A Silicon Carbide Chemical Vapor Deposition Reactor written by Matthew T. Smith and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2003 with categories.
ABSTRACT: The design and development of a reactor to make this process controlled and repeatable can be accomplished using theoretical and empirical tools. Fluid flow modeling, reactor sizing, low-pressure pumping and control are engineering concepts that were explored. Work on the design and development of an atmospheric pressure cold-wall CVD (APCVD) reactor will be presented. A detailed discussion of modifications to this reactor to permit hot-wall, low-pressure CVD (LPCVD) operation will then be presented. The consequences of this process variable change will be discussed as well as the necessary design parameters. Computational fluid dynamic (CFD) calculations, which predict the flow patterns of gases in the reaction tube, will be presented. Feasible CVD reactor design that results in laminar fluid flow control is a function of the prior mentioned techniques and will be presented.
Transport Phenomena Studies Via Computational Simulation In Structural Materials Processing
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Author :
language : en
Publisher:
Release Date : 1995
Transport Phenomena Studies Via Computational Simulation In Structural Materials Processing written by and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 1995 with categories.
The objective of the present STTR project is to develop computational tools necessary to simulate processing of structural materials. Processes considered are chemical vapor deposition (CVD) and chemical vapor infiltration In the Phase I work discussed in this report, an existing SRA computational fluid dynamics code has been adapted to apply to CVD modeling. Multicomponent diffusion, thermal diffusion, homogeneous and surface reactions and conjugate heat transfer have been included. A model for infiltration of porous preforms has been developed for CVI. The models and code were used to study CVD of silicon carbide, CVD of boron on tungsten wire, and CVI of SiC-SiC preforms. The models were first validate for silicon deposition. In all cases, it was demonstrated that numerical simulation can serve as a design tool by enabling cost-effective parametric study to understand mechanisms and allow optimization. (MM).
Numerical Modeling Tools For Chemical Vapor Deposition
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Author : National Aeronautics and Space Adm Nasa
language : en
Publisher: Independently Published
Release Date : 2018-11-07
Numerical Modeling Tools For Chemical Vapor Deposition written by National Aeronautics and Space Adm Nasa and has been published by Independently Published this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-11-07 with Science categories.
Development of general numerical simulation tools for chemical vapor deposition (CVD) was the objective of this study. Physical models of important CVD phenomena were developed and implemented into the commercial computational fluid dynamics software FLUENT. The resulting software can address general geometries as well as the most important phenomena occurring with CVD reactors: fluid flow patterns, temperature and chemical species distribution, gas phase and surface deposition. The physical models are documented which are available and examples are provided of CVD simulation capabilities. Jasinski, Thomas J. and Childs, Edward P. Unspecified Center...
Quantum Chemical Studies Of Deposition And Catalytic Surface Reactions
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Author : Emil Kalered
language : en
Publisher: Linköping University Electronic Press
Release Date : 2018-06-19
Quantum Chemical Studies Of Deposition And Catalytic Surface Reactions written by Emil Kalered and has been published by Linköping University Electronic Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-06-19 with categories.
Quantum chemical calculations have been used to model chemical reactions in epitaxial growth of silicon carbide by chemical vapor deposition (CVD) processes and to study heterogeneous catalytic reactions for methanol synthesis. CVD is a common method to produce high-quality materials and e.g. thin films in the semiconductor industry, and one of the many usages of methanol is as a promising future renewable and sustainable energy carrier. To optimize the chemical processes it is essential to understand the reaction mechanisms. A comprehensive theoretical model for the process is therefore desired in order to be able to explore various variables that are difficult to investigate in situ. In this thesis reaction paths and reaction energies are computed using quantum chemical calculations. The quantum-chemical results can subsequently be used as input for thermodynamic, kinetic and computational fluid dynamics modelling in order to obtain data directly comparable with the experimental observations. For the CVD process, the effect of halogen addition to the gas mixture is studied by modelling the adsorption and diffusion of SiH2, SiCl2 and SiBr2 on the (0001?) 4H-SiC surface. SiH2 was found to bind strongest to the surface and SiBr2 binds slightly stronger than the SiCl2 molecule. The diffusion barrier is shown to be lower for SiH2 than for SiBr2 and SiCl2 which have similar barriers. SiBr2 and SiCl2 are found to have similar physisorption energies and bind stronger than the SiH2 molecule. Gibbs free-energy calculations also indicate that the SiC surface is not fully hydrogen terminated at CVD conditions since missing-neighboring pair of surface hydrogens is found to be common. Calculations for the (0001) surface show that SiCl, SiCl2, SiHCl, SiH, and SiH2 likely adsorb on a methylene site, but the processes are thermodynamically less favorable than their reverse reactions. However, the adsorbed products may be stabilized by subsequent surface reactions to form a larger structure. The formation of these larger structures is found to be fast enough to compete with the desorption processes. Also the Gibbs free energies for adsorption of Si atoms, SiX, SiX2, and SiHX where X is F or Br are presented. Adsorption of Si atoms is shown to be the most thermodynamically favorable reaction followed by SiX, SiHX, and SiX2, X being a halide. The results in this study suggest that the major Si contributors in the SiC–CVD process are Si atoms, SiX and SiH. Methanol can be synthesized from gaseous carbon dioxide and hydrogen using solid metal-metal oxide mixtures acting as heterogeneous catalysts. Since a large surface area of the catalyst enhances the speed of the heterogeneous reaction, the use of nanoparticles (NP) is expected to be advantageous due to the NPs’ large area to surface ratio. The plasma-induced creation of copper NPs is investigated. One important element during particle growth is the charging process where the variation of the work function (W) with particle size is a key quantity, and the variation becomes increasingly pronounced at smaller NP sizes. The work functions are computed for a set of NP charge numbers, sizes and shapes, using copper as a case study. A derived analytical expression for W is shown to give quite accurate estimates provided that the diameter of the NP is larger than about a nanometer and that the NP has relaxed to close to a spherical shape. For smaller sizes W deviates from the approximative expression, and also depends on the charge number. Some consequences of these results for NP charging process are outlined. Key reaction steps in the methanol synthesis reaction mechanism using a Cu/ZrO2 nanoparticle catalyst is investigated. Two different reaction paths for conversion of CO2 to CO is studied. The two paths result in the same complete reaction 2 CO2 ? 2 CO + O2 where ZrO2 (s) acts as a catalyst. The highest activation energies are significantly lower compared to that of the gas phase reaction. The presence of oxygen vacancies at the surface appear to be decisive for the catalytic process to be effective. Studies of the reaction kinetics show that when oxygen vacancies are present on the ZrO2 surface, carbon monoxide is produced within a microsecond. The IR spectra of CO2 and H2 interacting with ZrO2 and Cu under conditions that correspond to the catalyzed CH3OH production process is also studied experimentally and compared to results from the theoretical computations. Surface structures and gas-phase molecules are identified through the spectral lines by matching them to specific vibrational modes from the literature and from the new computational results. Several surface structures are verified and can be used to pin point surface structures in the reaction path. This gives important information that help decipher how the reaction mechanism of the CO2 conversion and ultimately may aid to improve the methanol synthesis process.
Chemical Vapor Deposition Fluid Flow Simulation Modelling Tool
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Author : National Aeronautics and Space Administration NASA
language : en
Publisher:
Release Date : 2018-11-13
Chemical Vapor Deposition Fluid Flow Simulation Modelling Tool written by National Aeronautics and Space Administration NASA and has been published by this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-11-13 with categories.
Accurate numerical simulation of chemical vapor deposition (CVD) processes requires a general purpose computational fluid dynamics package combined with specialized capabilities for high temperature chemistry. In this report, we describe the implementation of these specialized capabilities in the spectral element code NEKTON. The thermal expansion of the gases involved is shown to be accurately approximated by the low Mach number perturbation expansion of the incompressible Navier-Stokes equations. The radiative heat transfer between multiple interacting radiating surfaces is shown to be tractable using the method of Gebhart. The disparate rates of reaction and diffusion in CVD processes are calculated via a point-implicit time integration scheme. We demonstrate the use above capabilities on prototypical CVD applications. Bullister, Edward T. Unspecified Center FLUID DYNAMICS; FLUID MECHANICS; GAS EXPANSION; HIGH TEMPERATURE; INCOMPRESSIBLE FLOW; MATHEMATICAL MODELS; NAVIER-STOKES EQUATION; RADIATIVE HEAT TRANSFER; REACTION KINETICS; THERMAL EXPANSION; VAPOR DEPOSITION; COMPUTATIONAL FLUID DYNAMICS; COMPUTERIZED SIMULATION; DIFFUSION...
Proceedings Of The Thirteenth International Conference On Chemical Vapor Deposition
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Author : Theodore M. Besmann
language : en
Publisher: The Electrochemical Society
Release Date : 1996
Proceedings Of The Thirteenth International Conference On Chemical Vapor Deposition written by Theodore M. Besmann and has been published by The Electrochemical Society this book supported file pdf, txt, epub, kindle and other format this book has been release on 1996 with Science categories.
Computational Fluid Dynamics And Comsol Multiphysics
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Author : Ashish S. Chaurasia
language : en
Publisher: CRC Press
Release Date : 2021-12-29
Computational Fluid Dynamics And Comsol Multiphysics written by Ashish S. Chaurasia and has been published by CRC Press this book supported file pdf, txt, epub, kindle and other format this book has been release on 2021-12-29 with Science categories.
This textbook covers computational fluid dynamics simulation using COMSOL Multiphysics® Modeling Software in chemical engineering applications. In the volume, the COMSOL Multiphysics package is introduced and applied to solve typical problems in chemical reactors, transport processes, fluid flow, and heat and mass transfer. Inspired by the difficulties of introducing the use of COMSOL Multiphysics software during classroom time, the book incorporates the author’s experience of working with undergraduate, graduate, and postgraduate students to make the book user friendly and that, at the same time, addresses typical examples within the subjects covered in the chemical engineering curriculum. Real-world problems require the use of simulation and optimization tools, and this volume shows how COMSOL Multiphysics software can be used for that purpose. Key features: • Includes over 500 step-by-step screenshots • Shows the graphical user interface of COMSOL, which does not require any programming effort • Provides chapter-end problems for extensive practice along with solutions • Includes actual examples of chemical reactors, transport processes, fluid flow, and heat and mass transfer This book is intended for students who want or need more help to solve chemical engineering assignments using computer software. It can also be used for computational courses in chemical engineering. It will also be a valuable resource for professors, research scientists, and practicing engineers.
Detailed Reaction Kinetics For Cfd Modeling Of Nuclear Fuel Pellet Coating For High Temperature Gas Cooled Reactors
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Author :
language : en
Publisher:
Release Date : 2008
Detailed Reaction Kinetics For Cfd Modeling Of Nuclear Fuel Pellet Coating For High Temperature Gas Cooled 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 2008 with categories.
The research project was related to the Advanced Fuel Cycle Initiative and was in direct alignment with advancing knowledge in the area of Nuclear Fuel Development related to the use of TRISO fuels for high-temperature reactors. The importance of properly coating nuclear fuel pellets received a renewed interest for the safe production of nuclear power to help meet the energy requirements of the United States. High-temperature gas-cooled nuclear reactors use fuel in the form of coated uranium particles, and it is the coating process that was of importance to this project. The coating process requires four coating layers to retain radioactive fission products from escaping into the environment. The first layer consists of porous carbon and serves as a buffer layer to attenuate the fission and accommodate the fuel kernel swelling. The second (inner) layer is of pyrocarbon and provides protection from fission products and supports the third layer, which is silicon carbide. The final (outer) layer is also pyrocarbon and provides a bonding surface and protective barrier for the entire pellet. The coating procedures for the silicon carbide and the outer pyrocarbon layers require knowledge of the detailed kinetics of the reaction processes in the gas phase and at the surfaces where the particles interact with the reactor walls. The intent of this project was to acquire detailed information on the reaction kinetics for the chemical vapor deposition (CVD) of carbon and silicon carbine on uranium fuel pellets, including the location of transition state structures, evaluation of the associated activation energies, and the use of these activation energies in the prediction of reaction rate constants. After the detailed reaction kinetics were determined, the reactions were implemented and tested in a computational fluid dynamics model, MFIX. The intention was to find a reduced mechanism set to reduce the computational time for a simulation, while still providing accurate results. Furthermore, fast chemistry techniques would be coupled to MFIX to effectively treat the complex chemistry thus improve the computational efforts. Based on the reaction kinetics modeling, it was determined that the detailed set of chemical reactions for the thermal decomposition of a methyltrichlorosilane (MTS)/H2 mixture consisted of 45 species and 114 gas-phase reactions. Further work identified a mechanism consisting of approximately 60 surface reactions for the surface chemistry of SiC chemical vapor deposition. A reduced mechanism for the MTS gas-phase pyrolysis was constructed using the scanning method based on optimization concepts, which consisted of only 28 species and 29 reactions. The benefits of this project are that we have determined gas-phase species produced during and after the various decomposition reactions of MTS. The success of the computational approaches can now be used to predict the complex chemistry associated with the CVD process in producing nuclear fuel. It is expected that the knowledge we acquired can be easily transferred and that it will contribute to further experimental investigations. Furthermore, the computational techniques can now be used for reactor design and optimization for the next generation of nuclear reactors.
Silicon Carbide And Related Materials 2017
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Author : Robert Stahlbush
language : en
Publisher: Trans Tech Publications Ltd
Release Date : 2018-06-05
Silicon Carbide And Related Materials 2017 written by Robert Stahlbush and has been published by Trans Tech Publications Ltd this book supported file pdf, txt, epub, kindle and other format this book has been release on 2018-06-05 with Technology & Engineering categories.
ICSCRM 2017 Selected, peer reviewed papers from the 2017 International Conference on Silicon Carbide and Related Materials (ICSCRM 2017), September 17-22, 2017, Washington, DC, USA