Download or read book Detailed Kinetic Modeling of Autoignition Chemistry written by Charles K. Westbrook and published by . This book was released on 1987 with total page 16 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Autoignition Chemistry in a Motored Engine written by and published by . This book was released on 1996 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Autoignition of isomers of pentane, hexane, and primary reference fuel mixture of n-heptane and iso-octane has been studied experimentally under motored engine conditions and computationally using a detailed chemical kinetic reaction mechanism. Computed and experimental results are compared and used to help understand the chemical factors leading to engine knock in spark-ignited engines. The kinetic model reproduces observed variations in critical compression ratio with fuel molecular size and structure, provides intermediate product species concentrations in good agreement with observations, and gives insights into the kinetic origins of fuel octane sensitivity. Sequential computed engine cycles were found to lead to stable, non-igniting behavior for conditions below a critical compression ratio; to unstable, oscillating but nonigniting behavior in a transition region; and eventually to ignition as the compression ratio is steadily increased. This transition is related to conditions where a negative temperature coefficient of reaction exists, which has a significant influence on octane number and fuel octane sensitivity.
Download or read book Cleaner Combustion written by Frédérique Battin-Leclerc and published by Springer Science & Business Media. This book was released on 2013-09-06 with total page 657 pages. Available in PDF, EPUB and Kindle. Book excerpt: This overview compiles the on-going research in Europe to enlarge and deepen the understanding of the reaction mechanisms and pathways associated with the combustion of an increased range of fuels. Focus is given to the formation of a large number of hazardous minor pollutants and the inability of current combustion models to predict the formation of minor products such as alkenes, dienes, aromatics, aldehydes and soot nano-particles which have a deleterious impact on both the environment and on human health. Cleaner Combustion describes, at a fundamental level, the reactive chemistry of minor pollutants within extensively validated detailed mechanisms for traditional fuels, but also innovative surrogates, describing the complex chemistry of new environmentally important bio-fuels. Divided into five sections, a broad yet detailed coverage of related research is provided. Beginning with the development of detailed kinetic mechanisms, chapters go on to explore techniques to obtain reliable experimental data, soot and polycyclic aromatic hydrocarbons, mechanism reduction and uncertainty analysis, and elementary reactions. This comprehensive coverage of current research provides a solid foundation for researchers, managers, policy makers and industry operators working in or developing this innovative and globally relevant field.
Download or read book Autoignition Chemistry of the Hexane Isomers written by and published by . This book was released on 1995 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: Autoignition of the five distinct isomers of hexane is studied experimentally under motored engine conditions and computationally using a detailed chemical kinetic reaction mechanism. Computed and experimental results are compared and used to help understand the chemical factors leading to engine knock in spark-ignited engines and the molecular structure factors contributing to octane rating for hydrocarbon fuels. The kinetic model reproduces observed variations in critical compression ratio with fuel structure, and it also provides intermediate and final product species concentrations in very dose agreement with observed results. In addition, the computed results provide insights into the kinetic origins of fuel octane sensitive.
Download or read book Low temperature Combustion and Autoignition written by M.J. Pilling and published by Elsevier. This book was released on 1997-11-27 with total page 823 pages. Available in PDF, EPUB and Kindle. Book excerpt: Combustion has played a central role in the development of our civilization which it maintains today as its predominant source of energy. The aim of this book is to provide an understanding of both fundamental and applied aspects of low-temperature combustion chemistry and autoignition. The topic is rooted in classical observational science and has grown, through an increasing understanding of the linkage of the phenomenology to coupled chemical reactions, to quite profound advances in the chemical kinetics of both complex and elementary reactions. The driving force has been both the intrinsic interest of an old and intriguing phenomenon and the centrality of its applications to our economic prosperity. The volume provides a coherent view of the subject while, at the same time, each chapter is self-contained.
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 Autoignition Delay Time Measurments and Chemical Kinetic Modeling of Hydrogen ammonia natural Gas Mixtures written by Jessica Blue Baker and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In general, both models were able to capture the trend in autoignition delay times and CO time histories for natural gas and ammonia mixtures. However, for ammonia-hydrogen mixtures, GRI 3.0 failed to predict ignition delay times, whereas the UCF 2022 mechanism was able to capture the IDTs within the uncertainty limits of the experiments. A sensitivity analysis was conducted for different mixtures to understand the important reactions at the experimental conditions. Finally, a reaction pathway analysis was carried out to understand important ammonia decomposition pathways in the presence of hydrogen and natural gas.
Download or read book Chemical Kinetic Modeling of Component Mixtures Relevant to Gasoline written by and published by . This book was released on 2008 with total page 8 pages. Available in PDF, EPUB and Kindle. Book excerpt: Detailed kinetic models of pyrolysis and combustion of hydrocarbon fuels are nowadays widely used in the design of internal combustion engines and these models are effectively applied to help meet the increasingly stringent environmental and energetic standards. In previous studies by the combustion community, such models not only contributed to the understanding of pure component combustion, but also provided a deeper insight into the combustion behavior of complex mixtures. One of the major challenges in this field is now the definition and the development of appropriate surrogate models able to mimic the actual features of real fuels. Real fuels are complex mixtures of thousands of hydrocarbon compounds including linear and branched paraffins, naphthenes, olefins and aromatics. Their behavior can be effectively reproduced by simpler fuel surrogates containing a limited number of components. Aside the most commonly used surrogates containing iso-octane and n-heptane only, the so called Primary Reference Fuels (PRF), new mixtures have recently been suggested to extend the reference components in surrogate mixtures to also include alkenes and aromatics. It is generally agreed that, including representative species for all the main classes of hydrocarbons which can be found in real fuels, it is possible to reproduce very effectively in a wide range of operating conditions not just the auto-ignition propensity of gasoline or Diesel fuels, but also their physical properties and their combustion residuals [1]. In this work, the combustion behavior of several components relevant to gasoline surrogate formulation is computationally examined. The attention is focused on the autoignition of iso-octane, hexene and their mixtures. Some important issues relevant to the experimental and modeling investigation of such fuels are discussed with the help of rapid compression machine data and calculations. Following the model validation, the behavior of mixtures is discussed on the basis of computational results.
Download or read book Modeling of Chemical Reactions written by R.W. Carr and published by Elsevier. This book was released on 2007-09-04 with total page 317 pages. Available in PDF, EPUB and Kindle. Book excerpt: Modeling of Chemical Reactions covers detailed chemical kinetics models for chemical reactions. Including a comprehensive treatment of pressure dependent reactions, which are frequently not incorporated into detailed chemical kinetic models, and the use of modern computational quantum chemistry, which has recently become an extraordinarily useful component of the reaction kinetics toolkit. It is intended both for those who need to model complex chemical reaction processes but have little background in the area, and those who are already have experience and would benefit from having a wide range of useful material gathered in one volume. The range of subject matter is wider than that found in many previous treatments of this subject. The technical level of the material is also quite wide, so that non-experts can gain a grasp of fundamentals, and experts also can find the book useful. A solid introduction to kinetics Material on computational quantum chemistry, an important new area for kinetics Contains a chapter on construction of mechanisms, an approach only found in this book
Download or read book Combustion written by J. Warnatz and published by Springer Science & Business Media. This book was released on 2006-09-23 with total page 389 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides a rigorous treatment of the coupling of chemical reactions and fluid flow. Combustion-specific topics of chemistry and fluid mechanics are considered and tools described for the simulation of combustion processes. This edition is completely restructured. Mathematical Formulae and derivations as well as the space-consuming reaction mechanisms have been replaced from the text to appendix. A new chapter discusses the impact of combustion processes on the atmosphere, the chapter on auto-ignition is extended to combustion in Otto- and Diesel-engines, and the chapters on heterogeneous combustion and on soot formation are heavily revised.
Download or read book Chemical Kinetic Modelling of Autoignition Under Conditions Relevant to Knock in Spark Ignition Engines written by Hakan Serhad Soyhan and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The phenomenon called the ''engine knock'' is an abnonnal combustion mode inspark ignition (SI) engines. it might lead to very high peak pressure in the cylinderand serious damages in engines. Knock limits the compression ratio of the ~ngine. The higher compression ratiomeans the higher fuel conversion efficiency of the engine. it also means highercylinder pressure and thereby higher gas temperature which can cause knock becauseof shorter ignition delay time. Increasing compression ratio is the simplest strategyfor increasing the efficiency of combustion, so a more detailed understanding of theprocesses goveming knock is important.it is generally accepted that knock is initiated by autoignition in the unbumed gasmixture as a result of compression due to the f1ame front propagation and the piston movement. Auto ignition can be defined as spontaneous ignition of some part of thecharge in the cylinder. The autoignition is may cause an extremely rapid chemicalenergy release. it causes a high local pressure and propagation of pressure waveswith high amplitude across the combustion chamber. The rapid rise in pressure andthe vibration of the resultant pressure wave across the combustion chamber cause erosion of the piston, piston rings and head gaskets. Known measures to avoid theoccurrence of engine knock cause either environmental problems, for example theusage of MTBE or reduce the engine thennal efficiency , for example lowcompression ratio, high swirl or early ignition timing. Because of this, the occurrenceof knock was subject of continuous public and industrial research.A detailed investigation of the combustion processes in intemal combustion engines is necessary for the improvement of engine technology .Chemical kinetic model ofthe combustion process implemented into the computational f1uid dynamic sapplications for the prediction of gas f1ow in the combustion chamber provides anefficient tool in tenns of time and cost for the investigation and improvement of the combustion process.The software tools for the modeling of combustion processes in combustion devicesrequire the reduction of the kinetic model to a limited number of species. Since the engine geometry is very complex, the performnnance of commercial software productsfor combustion device optimization decreases considerably if the number of species exceeds about 10. Consequently, a variety of methods in chemical kinetic modelingare needed to construct a reaction mechanism for a complex fuel such as PRF and toreduce it to a low number of capable species without a loss of information that mightbe important for the accuracy of the calculations. One method having the following steps is The generation of a ''detailed reaction mechanism'',The construction of the ''skeletal mechanism'',The final reduction of the reaction mechanism using Quasi Steady State Approximations (QSSA).This study concentrates on the construction of the problem oriented reduced mechanism. A method for automatic reduction of detailed kinetic to reduced mechanisms for complex fuels is proposed. The method is based on the simultaneoususe of sensitivity, reaction-f1ow and lifetime analyses. The sensitivity analysis detects species that the overall combustion process is sensitive on. Small in accuracies, in calculating these species, result in large errors in the characteristic behavior of the chernical scheme. Species, not relevant for the occurrence of autoignition in the end-gas, are defined as redundant. The automatic detection of there dundant species is done by means of an analysis of the reaction f1ows from and towards the most sensitive species, the fuel, the oxidizer and the final products. Theyare identified and eliminated for different pre-set levels of minimum reaction flow and sensitivity to generate a skeletal mechanism. The resulting skeletal mechanism is investigated with lifetime analysis to get the final reduced mechanism. A measure ofspecies lifetimes is taken from the diagonal elements of the Jacobian matrix of the chernical source terms. The species with the lifetime shorter than and mass-fractionIess than specified limits are assumed to be in steady state and selected for removalfrom the skeletal mechanism. The reduced mechanism is valid for the parameter range of initial and boundary values that the analysis has been performed for.The proposed reduction method is exemplified on a detailed reaction mechanism foriso-octane/n-heptane rnixtures. The gas-phase chernistry is analyzed in the end gas of an SI engine, using a two-zone model with conditions chosen relevant for engine knock. Comparing results obtained from the skeletal and the reduced mechanism swith results from the detailed mechanism shows the accuracy of the resulting mechanisms. it is shown that the error in the mechanisms increase with increasingpre-set Ievels of reduction. This is visualized by the help of the predicted crank angle degree at which auto ignition in the end gas of the engine occurs.The reduced mechanism is used for investigation of the modeling of the auto ignitionin the SI engines. The effects of engine operator parameters such as compression ratio, spark advance, fuel equivalence ratio and engine speed on autoignition onsettime have been studied.This work shows that it is possible to achieve a simplified reaction mechanism withgood agreement to the original mechanism by the reduction method. Fundamental knowledge about the detailed mechanism is not necessary to apply the method. Theprocedure used for reduction is fully automatic and provides a fast technique togenerate the problem oriented reduced mechanisms.
Download or read book A Study of Autoignition in a Premixed Charge Internal Combustion Engine Using Comprehensive Chemical Kinetics written by Philip Michael Dimpelfeld and published by . This book was released on 1985 with total page 534 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Low temperature Combustion and Autoignition written by and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Chemical Kinetic Characterization of Autoignition and Combustion of Surrogate Diesel written by K. Seshadri and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A study was performed to elucidate the chemical-kinetic mechanism of combustion of toluene. The research was performed in collaboration Dr. Charles Westbrook and Dr. William Pitz at Lawrence Livermore National Laboratory (LLNL). A detailed chemical-kinetic mechanism for toluene developed at LLNL was employed. Numerical calculations were performed using this mechanism and the results were compared with experimental data obtained from premixed and nonpremixed systems. Under premixed conditions, predicted ignition delay times were compared with new experimental data obtained by I. Da Costa, R. Fournet, F. Billaud, F. Battin-Leclerc at Departement de Chime Physique des Reactions, CNRS-ENSIC, BP. 451, 1, rue Grandville, 51001 Nancy, France. Also, calculated species concentration histories were compared to experimental flow reactor data from the literature. Under nonpremixed conditions, critical conditions of extinction and autoignition were measured in strained laminar flows in the counterflow configuration. Numerical calculations were performed using the chemical-kinetic mechanism at conditions corresponding to those in the experiments. Critical conditions of extinction and autoignition are predicted and compared with the experimental data. Comparisons between the model predictions and experimental results of ignition delay times in shock tube, and extinction and autoignition in nonpremixed systems show that the chemical-kinetic mechanism predicts that toluene/air is overall less reactive than observed in the experiments. The principal objective of this research is to obtain a fundamental understanding of the physical and chemical mechanisms of autoignition and combustion of Diesel in nonpremixed systems. The major components of Diesel are straight-chain paraffins, branched-chain paraffins, cycloparaffins, and aromatics. The results of this research on toluene are expected to be useful in understanding the role of aromatics in combustion of Diesel.
Download or read book Energy Research Abstracts written by and published by . This book was released on 1992 with total page 886 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Combustion written by Jürgen Warnatz and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: Combustion is an old technology, which at present provides about 90% of our worldwide energy support. Combustion research in the past used fluid mechanics with global heat release by chemical reactions described with thermodynamics, assuming infinitely fast reactions. This approach was useful for stationary combustion processes, but it is not sufficient for transient processes like ignition and quenching or for pollutant formation. Yet pollutant formation during combustion of fossil fuels is a central topic and will continue to be so in future. This book provides a detailed and rigorous treatment of the coupling of chemical reactions and fluid flow. Also, combustion-specific topics of chemistry and fluid mechanics are considered, and tools described for the simulation of combustion processes.
Download or read book Analysis of Kinetic Reaction Mechanisms written by Tamás Turányi and published by Springer. This book was released on 2014-12-29 with total page 369 pages. Available in PDF, EPUB and Kindle. Book excerpt: Chemical processes in many fields of science and technology, including combustion, atmospheric chemistry, environmental modelling, process engineering, and systems biology, can be described by detailed reaction mechanisms consisting of numerous reaction steps. This book describes methods for the analysis of reaction mechanisms that are applicable in all these fields. Topics addressed include: how sensitivity and uncertainty analyses allow the calculation of the overall uncertainty of simulation results and the identification of the most important input parameters, the ways in which mechanisms can be reduced without losing important kinetic and dynamic detail, and the application of reduced models for more accurate engineering optimizations. This monograph is invaluable for researchers and engineers dealing with detailed reaction mechanisms, but is also useful for graduate students of related courses in chemistry, mechanical engineering, energy and environmental science and biology.
