Download or read book Development of a Comprehensive and Predictive Reaction Mechanism of Liquid Hydrocarbon Combustion written by and published by . This book was released on 2007 with total page 9 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies were conducted in several relevant areas, including (1) validation of the chemistry and transport models against the extinction of ultra-lean premixed hydrogen-air mixtures, (2) a comprehensive theoretical analysis of the reaction kinetics of carbon monoxide and the hydroxyl radical, (3) a theoretical kinetic study of the decomposition of ethylene oxide; (4) a gas-kinetic analysis for the transport properties of long chain molecules in dilute gases, (5) quantum-chemistry, master equation modeling of the unimolecular decomposition of ortho-benzyne, (6) extension of the previously developed hydrogenicarbon model to combustion pressures as high as 600 atm, (7) an updated kinetic mechanism of small-hydrocarbon fuel combustion for use as a kinetic foundation of higher hydrocarbon combustion, and (8) a methodology for kinetic uncertainty propagation. These projects represent the two key ingredients for meeting the overall project objectives: (a) an accurate physico-chemical property database for combustion kinetics, and (b) a unified and optimized kinetic model for liquid aliphatic and aromatic fuel combustion with quantifiable uncertainties.
Download or read book Development of a Comprehensive and Predictive Reaction Mechanism of Liquid Hydrocarbon Fuel Combustion written by and published by . This book was released on 2004 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Studies were conducted to finalize a fundamental and predictive reaction model for the combustion of hydrogen and carbon monoxide through a multi-parameter optimization. These studies showed that reliable data of hydrogen and carbon monoxide oxidation at high temperatures can be reconciled be a single kinetic model. An advanced approach to solve the master equation of collision energy transfer was developed to predict the rate constants of combustion reactions of arbitrary complexities. Studies were also conducted on a class of unique combustion reactions that involve spin state crossing-one of the last few unresolved theoretical problems in combustion reaction kinetics.
Download or read book Development and Optimization of a Comprehensive Kinetic Model of Hydrocarbon Fuel Combustion written by and published by . This book was released on 2004 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this research program was to develop a comprehensive, predictive, and detailed kinetic model of hydrocarbon combustion for aero propulsion simulations. Sensitivity analyses were performed to examine the influences of the uncertainty in binary diffusion coefficients on flame simulations. First-principles calculations were carried out to determine the molecular binary diffusion coefficients of H-He, H2-He, H-H2, and H-Ar gas mixtures. This study resulted in an updated transport property library commonly used in combustion simulations. A new class of radical-chain initiation reactions was discovered for the homogeneous oxidation of unsaturated hydrocarbons. This element of the study utilized advanced quantum chemistry tools, reaction rate theory, and the method of detailed kinetic modeling. This new class of initiation reactions was found to be critical to reaction model development. A detailed reaction model of C1-C4 fuel combustion was updated. The foundation of this model, namely the H2/CO sub-model, was revised completely and optimized. A new method, termed the Sensitivity Analysis Based (SAB) method, was developed for rapid model optimization. The method was shown to be far more efficient than the factorial design method used in previous kinetic model optimization efforts.
Download or read book Chemistry of Hydrocarbon Combustion written by David. Hucknall and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 423 pages. Available in PDF, EPUB and Kindle. Book excerpt: The scientific and economic importance of the high-temperature reactions of hydrocarbons in both the presence and absence of oxygen cannot be overemphasized. A vast chemical industry exists based on feedstocks produced by the controlled pyrolysis of hydrocarbons, while uncontrolled combustion in air is still among the most important sources of heat and mechanical energy. The detonation and explosion of hydrocarbon-oxidant mixtures can however, be a highly dangerous phenomenon which destroys lives and equipment. In order that control can be exerted over combustion processes, a complete description of hydrocarbon oxidation and pyrolysis is required. A major contribution to this is an understanding of the unstable intermediates involved and their reactions. The aim of this book is to review our knowledge of the chemistry of hydrocarbon combustion and to consider the data which are available for relevant reactions. Chapter 1 describes early studies in which the apparent complexity of the chemistry was established and the type of information required for a better understanding was defined. Experimental studies of the overall process which were carried out with the aim of establishing the sequence of stable chemical intermediates and some of the unstable species are described in Chapter 2. The limited nature of the information thus obtained showed that independent studies of individual reactions involving the unstable species were required. In Chapter 3 investigations specifically aimed at the determination of the kinetics of elementary reactions are discussed.
Download or read book A New Comprehensive Reaction Mechanism for Combustion of Hydrocarbon Fuels written by and published by . This book was released on 1993 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: A chemical kinetic model has been developed which describes pyrolysis, ignition and oxidation of many small hydrocarbon fuels over a wide range of experimental conditions. Fuels include carbon monoxide and hydrogen, methane and other alkane species up to n-butane, ethylene, propene, acetylene, and oxygenated species such as methanol, acetaldehyde and ethanol. Formation of some larger intermediate and product species including benzene, butadiene, large olefins, and cyclopentadiene has been treated in a semi-empirical manner. The reaction mechanism has been tested for conditions that do not involve transport and diffusional processes, including plug flow and stirred reactors, batch reactors and shock tubes. The present kinetic model and its validation differ from previous reaction mechanisms in two ways. First, in addition to conventional combustion data, experiments more commonly associated with chemical engineering problems such as oxidative coupling, oxidative pyrolysis and steam cracking are used to test the reaction mechanism, making it even more general than previous models. In addition, H atom abstraction and some other reaction rates, even for the smaller C2, C3 and C4 species, are treated using approximations that facilitate future extensions to larger fuels in a convenient manner. Construction of the reaction mechanism and comparisons with experimental data illustrate the generality of the model.
Download or read book Comprehensive Mechanisms for Combustion Chemistry written by and published by . This book was released on 2009 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This project was an integrated experimental/numerical effort to study pyrolysis and oxidation reactions and mechanisms for small-molecule hydrocarbon structures under conditions representative of combustion environments. The experimental aspects of the work were conducted in large-diameter flow reactors, at 0.3 to 18 atm pressure, 500 to 1100 K temperature, and 10-2 to 2 seconds reaction time. Experiments were also conducted to determine reference laminar flame speeds using a premixed laminar stagnation flame experiment and particle image velocimetry, as well as pressurized bomb experiments. Flow reactor data for oxidation experiments include: (1)adiabatic/isothermal species time-histories of a reaction under fixed initial pressure, temperature, and composition; to determine the species present after a fixed reaction time, initial pressure; (2)species distributions with varying initial reaction temperature; (3)perturbations of a well-defined reaction systems (e.g. CO/H2/O2 or H2/O2)by the addition of small amounts of an additive species. Radical scavenging techniques are applied to determine unimolecular decomposition rates from pyrolysis experiments. Laminar flame speed measurements are determined as a function of equivalence ratio, dilution, and unburned gas temperature at 1 atm pressure. Hierarchical, comprehensive mechanistic construction methods were applied to develop detailed kinetic mechanisms which describe the measurements and literature kinetic data. Modeling using well-defined and validated mechanisms for the CO/H2/Oxidant systems and perturbations of oxidation experiments by small amounts of additives were also used to derive absolute reaction rates and to investigate the compatibility of published elementary kinetic and thermochemical information. Numerical tools were developed and applied to assess the importance of individual elementary reactions to the predictive performance of the developed mechanisms and to assess the uncertainties in elementary rate constant evaluations.
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 500 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Role of Comprehensive Detailed Chemical Kinetic Reaction Mechanisms in Combustion Research written by and published by . This book was released on 2008 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent developments by the authors in the field of comprehensive detailed chemical kinetic reaction mechanisms for hydrocarbon fuels are reviewed. Examples are given of how these mechanisms provide fundamental chemical insights into a range of combustion applications. Practical combustion consists primarily of chemical heat release from reactions between a fuel and an oxidizer, and computer simulations of practical combustion systems have become an essential tool of combustion research (Westbrook et al., 2005). At the heart of most combustion simulations, the chemical kinetic submodel frequently is the most detailed, complex and computationally costly part of a system model. Historically, the chemical submodel equations are solved using time-implicit numerical algorithms, due to the extreme stiffness of the coupled rate equations, with a computational cost that varies roughly with the cube of the number of chemical species in the model. While early mechanisms (c. 1980) for apparently simple fuels such as methane (Warnatz, 1980) or methanol (Westbrook and Dryer, 1979) included perhaps 25 species, current detailed mechanisms for much larger, more complex fuels such as hexadecane (Fournet et al., 2001; Ristori et al., 2001; Westbrook et al., 2008) or methyl ester methyl decanoate (Herbinet et al., 2008) have as many as 2000 or even 3000 species. Rapid growth in capabilities of modern computers has been an essential feature in this rapid growth in the size and complexity of chemical kinetic reaction mechanisms.
Download or read book Automatic Reaction Mechanism Generation written by Connie Wu Gao and published by . This book was released on 2016 with total page 204 pages. Available in PDF, EPUB and Kindle. Book excerpt: Growing awareness of climate change and the risks associated with our society's dependence on fossil fuels has motivated global initiatives to develop economically viable, renewable energy sources. However, the transportation sector remains a major hurdle. Although electric vehicles are becoming more mainstream, the transportation sector is expected to continue relying heavily on combustion engines, particularly in the freight and airline industries. Therefore, research efforts to develop cleaner combustion must continue. This includes the development of more efficient combustion engines, identification of compatible alternative fuels, and the streamlining of existing petroleum resources. These dynamic systems have complex chemistry and are often difficult and expensive to probe experimentally, making detailed chemical kinetic modeling an attractive option for simulating and predicting macroscopic observables such as ignition delay or CO2 concentrations. This thesis presents several methods and applications towards high fidelity predictive modeling using Reaction Mechanism Generator (RMG), an open source software package which automatically constructs kinetic mechanisms. Several sources contribute to model error during automatic mechanism generation, including incomplete or incorrect handling of chemistry, poor estimation of thermodynamic and kinetics parameters, and uncertainty propagation. First, an overview of RMG is presented along with algorithmic changes for handling incomplete or incorrect chemistry. Completeness of chemistry is often limited by CPU speed and memory in the combinational problem of generating reactions for large molecules. A method for filtering reactions is presented for efficiently and accurately building models for larger systems. An extensible species representation was also implemented based on chemical graph theory, allowing chemistry to be extended to lone pairs, charges, and variable valencies. Several chemistries are explored in this thesis through modeling three combustion related processes. Ketone and cyclic ether chemistry are explored in the study of diisoproyl ketone and cineole, biofuel candidates produced by fungi in the decomposition of cellulosic biomass. Detailed kinetic modeling in conjunction with engine experiments and metabolic engineering form a collaborative feedback loop that efficiently screens biofuel candidates for use in novel engine technologies. Next, the challenge of modeling constrained cyclic geometries is tackled in generating a combustion model of JP-10, a synthetic jet fuel used in propulsion technologies. The model is validated against experimental and literature data and succeeds in capturing key product distributions, including aromatic compounds, which are precursors to polyaromatic hydrocarbons (PAHs) and soot. Finally, oil-to-gas cracking processes under geological conditions are studied through modeling the low temperature pyrolysis of the heavy oil analog phenyldodecane in the presence of diethyldisulfide. This system is used to gather mechanistic insight on the observation that sulfur-rich kerogens have accelerated oil-to-gas decomposition, a topic relevant to petroleum reservoir modeling. The model shows that free radical timescales matter in low temperature systems where alkylaromatics are relatively stable. Local and global uncertainty propagation methods are used to analyze error in automatically generated kinetic models. A framework for local uncertainty analysis was implemented using Cantera as a backend. Global uncertainty analysis was implemented using adaptive Smolyak pscudospcctral approximations to efficiently compute and construct polynomial chaos expansions (PCE) to approximate the dependence of outputs on a subset of uncertain inputs. Both local and global methods provide similar qualitative insights towards identifying the most influential input parameters in a model. The analysis shows that correlated uncertainties based on kinetics rate rules and group additivity estimates of thermochemistry drastically reduce a model's degrees of freedom and can have a large impact on model outputs. These results highlight the necessity of uncertainty analysis in the mechanism generation workflow. This thesis demonstrates that predictive chemical kinetics can aid in the mechanistic understanding of complex chemical processes and contributes new methods for refining and building high fidelity models in the automatic mechanism generation workflow. These contributions are available to the kinetics community through the RMG software package.
Download or read book Solid Propellant Chemistry Combustion and Motor Interior Ballistics 1999 written by Vigor Yang and published by AIAA. This book was released on 2000 with total page 1038 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Comprehensive Mechanisms for Combustion Chemistry written by and published by . This book was released on 1992 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research program is an integrated effort to determine the reaction mechanisms responsible for the oxidation of small molecule hydrocarbon structures under conditions representative of combustion environments. The experimental aspects of the work are conducted in an atmospheric pressure flow reactor (APFR) as well as in a new variable pressure flow reactor (VPFR) facility which extends the ranges of parameters available in the APFR, particularly the pressure, (1--15 atm.), the temperature (600 K to 1200 K), and the observation time (10 to 5000 milli-seconds). Gas sampling of stable reactant, intermediate, and product species concentrations provide substantial definition of not only the phenomenology of reaction mechanisms, but a much more constrained set of pure kinetic information than can be derived in flames, or shock tubes. Analytical techniques used for detecting hydrocarbons and carbon oxides include gas chromatography, gas chromatography/mass spectrometry for off-time analyses. Non-dispersive infrared and Fourier transform. Infrared methods are utilized for continuous on-line sample detection of light hydrocarbons, carbon oxides, and oxygenated species. The modeling aspects of the program emphasize the use of hierarchical mechanistic construction along with path and elemental gradient sensitivity analyses in developing detailed kinetic mechanisms. Modeling using a well defined and validated mechanism for the CO/H2/Oxidant systems and perturbations of experimental oxidations by small amounts of additives are also used to derive absolute reaction rates and to investigate the compatibility of elementary kinetic rate information.
Download or read book Predicting Combustion Properties of Hydrocarbon Fuel Mixtures written by Claude Franklin Goldsmith (III.) and published by . This book was released on 2010 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, I applied computational quantum chemistry to improve the accuracy of kinetic mechanisms that are used to model combustion chemistry. I performed transition state theory calculations for several reactions that are critical in combustion, including a detailed analysis of the pressure dependence of these rate coefficients. I developed a new method for rapidly estimating the vibrational modes and hindered rotor parameters for molecules. This new method has been implemented in an automatic reaction mechanism generation software, RMG, and has improved the accuracy of the density of states computed in RMG, which in turn has improved RMG's ability to predict the pressure-dependence of rate coefficients for complex reaction networks. I used statistical mechanics to compute the thermochemistry for over 170 of the most important species in combustion. These calculations form a new library of thermodynamic parameters, and this library will improve the accuracy of kinetic models, particularly for fuel lean conditions. I measured reaction rate coefficients using both laser flash-photolysis absorption spectroscopy in a slow-flow reactor and time-of-flight mass spectrometry and laser Schlieren densitometry in a shock tube. Based upon these experimental projects, I helped design a one-of-a-kind instrument for measuring rate coefficients for combustion-relevant reactions. The new reactor combines photoionization time-of-flight mass spectrometry with multi-pass absorption spectroscopy in a laser-flash photolysis cell. The cumulative effect of these efforts should advance our understanding of combustion chemistry and allow us to make more accurate predictions of how hydrocarbons burn.
Download or read book Joint Meeting of the U S Sections of the Combustion Institute Western States Central States Eastern States written by and published by . This book was released on 2005 with total page 138 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Gas Phase Combustion Chemistry written by W.C., Jr. Gardiner and published by Springer Science & Business Media. This book was released on 1999-12-10 with total page 564 pages. Available in PDF, EPUB and Kindle. Book excerpt: Superseding Gardiner's "Combustion Chemistry", this is an updated, comprehensive coverage of those aspects of combustion chemistry relevant to gas-phase combustion of hydrocarbons. The book includes an extended discussion of air pollutant chemistry and aspects of combustion, and reviews elementary reactions of nitrogen, sulfur and chlorine compounds that are relevant to combustion. Methods of combustion modeling and rate coefficient estimation are presented, as well as access to databases for combustion thermochemistry and modeling.
Download or read book Turbulent Combustion written by Norbert Peters and published by Cambridge University Press. This book was released on 2000-08-15 with total page 322 pages. Available in PDF, EPUB and Kindle. Book excerpt: The combustion of fossil fuels remains a key technology for the foreseeable future. It is therefore important that we understand the mechanisms of combustion and, in particular, the role of turbulence within this process. Combustion always takes place within a turbulent flow field for two reasons: turbulence increases the mixing process and enhances combustion, but at the same time combustion releases heat which generates flow instability through buoyancy, thus enhancing the transition to turbulence. The four chapters of this book present a thorough introduction to the field of turbulent combustion. After an overview of modeling approaches, the three remaining chapters consider the three distinct cases of premixed, non-premixed, and partially premixed combustion, respectively. This book will be of value to researchers and students of engineering and applied mathematics by demonstrating the current theories of turbulent combustion within a unified presentation of the field.
Download or read book International Aerospace Abstracts written by and published by . This book was released on 1998 with total page 980 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fluid Mechanics Aspects of Fire and Smoke Dynamics in Enclosures written by Bart Merci and published by CRC Press. This book was released on 2022-10-24 with total page 424 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides essential understanding of flows in fire and smoke dynamics in enclosures, covering combustion, heat transfer and fire suppression in more detail than other introductory books. It moves from the basic equations for turbulent flows with combustion, through a discussion of the structure of flames, to fire and smoke plumes and their interaction with enclosure boundaries. This is then applied to fire dynamics and smoke and heat control in enclosures. This new edition provides considerably more on the fluid mechanics of the effect of water, and on fire dynamics modelling using Computational Fluid Dynamics. Presents worked examples taken from practical, everyday fire-related problems Covers a broad range of topics, from the basics to state-of-the-art computer simulations of fire and smoke-related fluid mechanics, including the effect of water Provides extensive treatment of the interaction of water sprays with a fire-driven flow Contains a chapter on Computational Fluid Dynamics, the increasingly popular calculation method in the field of fire safety science The book serves as a comprehensive guide at the undergraduate and starting researcher level on fire and smoke dynamics in enclosures, with an emphasis on fluid mechanics.
