Download or read book Shock Tube Study of the Reactions of the Hydroxyl Radical with Combustion Species and Pollutants Final Report written by and published by . This book was released on 1998 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: Shock heating t-butyl hydroperoxide behind a reflected shock wave has proved to be as a convenient source of hydroxyl radicals at temperatures near 1000 K. We applied this technique to the measurement of reaction rate coefficients of OH with several species of interest in combustion chemistry, and developed a thermochemical kinetics/transition state theory (TK-TST) model for predicting the temperature dependence of OH rate coefficients.
Download or read book A Shock Tube Study of the Reactions of the Hydroxyl Radical with Combustion Species and Pollutants written by and published by . This book was released on 1992 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: To extend the database of reliable high temperature measurements of OH radicals with hydrocarbons and other fuels and their decomposition products, we undertook, a research program with both experimental and computational tasks. The experimental goal was to design a procedure for measuring, at combustion temperatures, the reaction rate coefficients of OH radicals with fuels and other species of importance in combustion or propulsion systems. The computational effort was intended to refine the semi-empirical thermochemical kinetics/ transition-state-theory (TK-TST) procedures for extrapolating rate coefficients of reactions of OH with combustion species of interest, for predicting rate coefficients for species not studied in the laboratory, and to examine the ability of the theory to predict rate coefficients for different pathways in cases where the reagent possessed nonequivalent H atoms.
Download or read book A Shock Tube Study of the Reactions of the Hydroxyl Radical with Combustion Species and Pollutants Progress Report written by and published by . This book was released on 1992 with total page 10 pages. Available in PDF, EPUB and Kindle. Book excerpt: To extend the database of reliable high temperature measurements of OH radicals with hydrocarbons and other fuels and their decomposition products, we undertook, a research program with both experimental and computational tasks. The experimental goal was to design a procedure for measuring, at combustion temperatures, the reaction rate coefficients of OH radicals with fuels and other species of importance in combustion or propulsion systems. The computational effort was intended to refine the semi-empirical thermochemical kinetics/ transition-state-theory (TK-TST) procedures for extrapolating rate coefficients of reactions of OH with combustion species of interest, for predicting rate coefficients for species not studied in the laboratory, and to examine the ability of the theory to predict rate coefficients for different pathways in cases where the reagent possessed nonequivalent H atoms.
Download or read book A Shock Tube Study of the Reactions of the Hydroxyl Radical with Combustion Species written by and published by . This book was released on 1991 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The reactions of OH radicals with hydrocarbons have received a great deal of attention in recent years because of these processes are principal steps in the oxidation of organic fuels -- whether occurring in combustion/propulsion systems, in the atmosphere, or elsewhere. Of the various radicals capable of attacking hydrocarbons, OH radicals are generally the most reactive, and their reactions directly yield water molecules, one of the major final oxidation products. In the atmosphere, the combined effect of the OH radical's reactivity and concentration make it the single species that determines the atmospheric lifetime of an organic substance. The principal goals of the kineticist in the field of oxidation chemistry are (1) to measure as many elementary reaction rate coefficients as are conveniently studied in the laboratory; and (2) to develop theoretical and/or semiempirical tools for extrapolating from measured rate coefficients to unmeasured ones. The latter step is necessary because of the sheer number of reactions of possible interest.
Download or read book A Shock Tube Study of the Reactions of the Hydroxyl Radical with Combustion Species Progress Report June 1990 May 1991 written by and published by . This book was released on 1991 with total page 5 pages. Available in PDF, EPUB and Kindle. Book excerpt: The reactions of OH radicals with hydrocarbons have received a great deal of attention in recent years because of these processes are principal steps in the oxidation of organic fuels -- whether occurring in combustion/propulsion systems, in the atmosphere, or elsewhere. Of the various radicals capable of attacking hydrocarbons, OH radicals are generally the most reactive, and their reactions directly yield water molecules, one of the major final oxidation products. In the atmosphere, the combined effect of the OH radical's reactivity and concentration make it the single species that determines the atmospheric lifetime of an organic substance. The principal goals of the kineticist in the field of oxidation chemistry are (1) to measure as many elementary reaction rate coefficients as are conveniently studied in the laboratory; and (2) to develop theoretical and/or semiempirical tools for extrapolating from measured rate coefficients to unmeasured ones. The latter step is necessary because of the sheer number of reactions of possible interest.
Download or read book Shock Tube Studies of Elementary Hydroxyl radical Reactions Important in Combustion Systems written by Margaret Stacey Wooldridge and published by . This book was released on 1995 with total page 260 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Shock tube Study of the Reaction H O2 Ar rightward pointing Arrow HO2 Ar written by Casimir J. Jachimowski and published by . This book was released on 1972 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Energy Research Abstracts written by and published by . This book was released on 1994 with total page 444 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Shock Tube Study of Nitrogen containing Fuels written by Sijie Li and published by . This book was released on 2014 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The combustion chemistry of nitrogen-containing fuels is important in the study of bio-derived fuels and nitrogen-based propellants. However, little high-quality shock tube kinetics data exists for these systems. The primary objective of the research presented in this dissertation is to augment the experimental database and to improve understanding of the chemical kinetics for four nitrogen-containing fuels: morpholine, dimethylamine, ethylamine and monomethylhydrazine. Morpholine (C4H9NO, 1-oxa-4-aza-cyclohexane) is a good representative candidate of a nitrogen-containing fuel because of its cyclic structure and wide industrial applications. Morpholine ignition delay times were measured behind reflected shock waves. A morpholine mechanism was developed based on this shock tube study and previous works in the literature. The simulations from this morpholine mechanism were in good agreement with the current morpholine experiments as well as previous morpholine flame data. Refinement of this morpholine mechanism required improvements in the sub-mechanisms of two major intermediate species dimethylamine and ethylamine, as discussed in a progressive manner in this dissertation. The overall rate constants of hydroxyl radicals (OH) with dimethylamine (DMA: CH3NHCH3) and ethylamine (EA: CH3CH2NH2) were measured behind reflected shock waves using UV laser absorption of OH radicals near 306.7 nm. The overall rate constants were determined by fitting the measured OH time-histories with the computed profiles using the detailed dimethylamine and ethylamine sub-mechanisms contained in the morpholine mechanism. Variational transition state theory was used to compute the H-abstraction rates by OH for dimethylamine and ethylamine. The calculated reaction rate constants are in good agreement with the experiment. The calculated reaction rate constants were used to update the morpholine mechanism for simulations in the following sections. Dimethylamine (DMA) ignition delay times and OH time-histories were investigated behind reflected shock waves. The dimethylamine ignition delay time measurements were carried out in 4% oxygen/argon. OH time-histories were measured in stoichiometric mixtures of 500 ppm DMA/O2/argon. The morpholine mechanism was then updated by adding the DMA unimolecular decomposition channel: DMA = CH3NH + CH3. With this modification, the simulation results are in excellent agreement with both the dimethylamine ignition delay times and OH time-history data. Ethylamine (CH3CH2NH2) pyrolysis and oxidation were studied behind reflected shock waves. For ethylamine pyrolysis, NH2 time-histories were measured in 2000 ppm ethylamine/argon mixtures. For ethylamine oxidation, ignition delay times, NH2 and OH time-histories were measured in ethylamine/O2/argon mixtures. By fitting the simulations to the early time-histories of NH2 and OH, the rate constants for the two major ethylamine decomposition pathways in the morpholine mechanism were updated for better agreement with the experiment. In addition, recommendations from recent theoretical studies of ethylamine radical reactions were implemented. With these modifications, the final updated morpholine mechanism provides significantly improved agreement with the species time-history measurements and the ignition delay times of ethylamine. The morpholine mechanism, after implementing the aformentioned updates based on the dimethylamine and ethylamine data, was compared with the morpholine ignition delay time data again. It was shown that those modifications improve the agreements of the mechanism with the morpholine data. Amine groups are common structural features for rocket propellants as well, and using the same approach as above, the pyrolysis of an important propellant monomethylhydrazine (MMH) was studied using NH2 time-histories in MMH/argon mixtures. The MMH pyrolysis mechanism developed by Sun et al. (2009), with the updates by Cook et al. (2011), was used to compare with the experiment. The rate constant of the reaction: MMH = CH3N.H + NH2 was determined based on early time of the NH2 time-histories. Pressure dependence of this reaction was observed at 0.3-5 atm. The measured reaction rate constants follow a pressure dependence trend close to the theoretical results by Zhang et al. (2011) based on transition state theory master equation analysis. Using the high and low-pressure limit expressions by Zhang et al., a new Troe's expression in the fall-off region was proposed based on the current experimental data. Utilizing the later times of the NH2 time-histories, a new reaction rate expression was recommended for the reaction: NHNH2 + H = NH2 + NH2.
Download or read book Measuring Hydroxyl Radicals During the Oxidation of Methane Ethane Ethylene and Acetylene in a Shock Tube Using UV Absorption Spectroscopy written by Christopher Joseph Erik Aul and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The hydroxyl (OH) radical is a common intermediate species in any hydrogen- or hydrocarbon-based flame. Investigating OH at elevated temperatures and pressures is not a trivial task, and many considerations must be made to fully study the molecule. Shock tubes can provide the experimenter with a wide range of temperatures and pressures to investigate a variety of combustion characteristics including, but not limited to, OH kinetic profiles. Described in this dissertation is the diagnostic used to measure OH within a shock tube using UV absorption spectroscopy from an enhanced UV Xenon lamp passed through a spectrometer. OH absorption was made over a narrow range of wavelengths around 309.551 nm within the widely studied OH X-->A ground vibrational transition region. Experiments have been performed in the shock-tube facility at Texas A&M University using this OH absorption diagnostic. A calibration mixture of stoichiometric H2/O2 diluted in 98% argon by volume was tested initially and compared with a well-known hydrogen-based kinetics mechanism to generate an absorption coefficient correlation. This correlation is valid over the range of conditions observed in the experiments at two pressures near 2 and 13 atm and temperatures from 1182 to 2017 K. Tests were completed using the absorption coefficient correlation on stoichiometric mixtures of methane, methane and water, ethane, ethylene, and acetylene to compare against a comprehensive, detailed chemical kinetics mechanism which considers up through C5 hydrocarbons. Measurements of methane show good agreement in peak OH formation and ignition delay time when compared with the mechanism. Improvements can be made in the shape of the methane-oxygen OH profile, and sensitivity and rate of production analyses were performed with the mechanism to identify key reactions for tuning. Similar results were found for methane-water-oxygen mixtures with no difference in profile shape or ignition delay time noted. There is room for improvement between the mechanism and measured values of OH for ethane-, ethylene-, and acetylene-based mixtures, although interesting pre-ignition features are nonetheless captured relatively well by the mechanism. Uncertainty in the measurement comes from the inherent noise in the photomultiplier tube signal and is ±25-150 ppm for the 2-atm experiments and ±6-25 ppm for the 13-atm experiments. The electronic version of this dissertation is accessible from http://hdl.handle.net/1969.1/149534
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1994 with total page 836 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Shock Tube Investigations of the Reaction Kinetics of Small Unsaturated Hydrocarbon Species written by Ravi Xavier Fernandes and published by Cuvillier Verlag. This book was released on 2004 with total page 133 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Computational Study of the Chemical Kinetics of Hydrogen Combustion written by T. L. Burks and published by . This book was released on 1981 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt: A set of elementary reactions and their corresponding rate coefficients has been assembled to describe the homogeneous H2-O2 reaction system over the temperature range 300-3000 K. The reaction mechanism was drawn together assuming that H2-O2 reactive mixtures could be adequately described in terms of self-consistent, thermal distributions of electronically neutral, ground-state reactants, intermediates and products. The resulting time-dependent ordinary differential equations describing the system were integrated assuming various initial pressures, temperatures and initial concentrations of reactants and diluents. The computed results have been compared with experimentally observed induction times, second explosion limits, the rate of reaction above the second explosion limit and the temporal behavior of reaction species. The good agreement between the computational and experimental results attests to the accuracy of the assembled mechanism in its description of the homogeneous reaction system and supports the validity of the set of associated rate coefficients for the elementary reactions of the mechanism over a broad range of reaction conditions. (Author).
Download or read book The Shock Tube in High Temperature Chemical Physics written by Alfred Gordon Gaydon and published by . This book was released on 2013-03 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Shock tube investigations of the reaction kinetics of small unsaturated hydrocarbon species written by and published by Cuvillier Verlag. This book was released on 2004-07-29 with total page 132 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Mechanisms of Atmospheric Oxidation of the Alkanes written by Jack G Calvert and published by Oxford University Press. This book was released on 2008-09-15 with total page 1005 pages. Available in PDF, EPUB and Kindle. Book excerpt: An international team of eminent atmospheric scientists have prepared Mechanisms of Atmospheric Oxidation of the Alkanes as an authoritative source of information on the role of alkanes in the chemistry of the atmosphere. The book includes the properties of the alkanes and haloalkanes, as well as a comprehensive review and evaluation of the existing literature on the atmospheric chemistry of the alkanes and their major atmospheric oxidation products, and the various approaches now used to model the alkane atmospheric chemistry. Comprehensive coverage is given of both the unsubstituted alkanes and the many haloalkanes. All the existing quality measurements of the rate coefficients for the reactions of OH, Cl, O(3P), NO3, and O3 with the alkanes, the haloalkanes, and their major oxidation products have been reviewed and evaluated. The expert authors then give recommendations of the most reliable kinetic data. They also review the extensive literature on the mechanisms and rates and modes of photodecomposition of the haloalkanes and the products of atmospheric oxidation of the alkanes and the haloalkanes, and make recommendations for future use by atmospheric scientists. The evaluations presented allow an extrapolation of the existing kinetic and photochemical data to those alkanes and haloalkanes that are as yet unstudied. The current book should be of special interest and value to the modelers of atmospheric chemistry as a useful input for development of realistic modules designed to simulate the atmospheric chemistry of the alkanes, their major oxidation products, and their influence on ozone and other trace gases within the troposphere.
Download or read book Shock Tube Study of the Reaction H Plus O2 Plus Ar Yields HO2 Plus Ar written by C. J. Jachimowski and published by . This book was released on 1972 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
