Download or read book Modeling Simplified Reaction Mechanisms Using Continuous Thermodynamics for Hydrocarbon Fuels written by Clayton D.L. Fox and published by . This book was released on 2018 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Commercial fuels are mixtures with large numbers of components. Continuous thermodynamics is a technique for modelling fuel mixtures using a probability density function rather than dealing with each discreet component. The mean and standard deviation of the distribution are then used to model the chemical reactions of the mixture. This thesis develops the necessary theory to apply the technique of continuous thermodynamics to the oxidation reactions of hydrocarbon fuels. The theory is applied to three simplified models of hydrocarbon oxidation: a global one-step reaction, a two-step reaction with CO as the intermediate product, and the four-step reaction of Müller et al. (1992), which contains a high- and a low-temperature branch. These are all greatly simplified models of the complex reaction kinetics of hydrocarbons, and in this thesis they are applied specifically to n-paraffin hydrocarbons in the range from n-heptane to n-hexadecane. The model is tested numerically using a simple constant pressure homogeneous ignition problem using Cantera and compared to simplified and detailed mechanisms for n-heptane. The continuous thermodynamics models are able not only to predict ignition delay times and the development of temperature and species concentrations with time, but also changes in the mixture composition as reaction proceeds as represented by the mean and standard deviation of the distribution function. Continuous thermodynamics is therefore shown to be a useful tool for reactions of multicomponent mixtures, and an alternative to the "surrogate fuel" approach often used at present.
Download or read book Combustion written by J. Warnatz and published by Springer Science & Business Media. This book was released on 2006-08-18 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 A CHEMICAL KINETIC REACTION MECHANISM AND THERMODYNAMIC DATABASE FOR FUEL RICH HYDROCARBON COMBUSTION MODELING written by EMERY. PUSKAS and published by . This book was released on 1993 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Reduced Kinetic Mechanisms for Applications in Combustion Systems written by Norbert Peters and published by Springer Science & Business Media. This book was released on 2008-09-11 with total page 364 pages. Available in PDF, EPUB and Kindle. Book excerpt: In general, combustion is a spatially three-dimensional, highly complex physi co-chemical process oftransient nature. Models are therefore needed that sim to such a degree that it becomes amenable plify a given combustion problem to theoretical or numerical analysis but that are not so restrictive as to distort the underlying physics or chemistry. In particular, in view of worldwide efforts to conserve energy and to control pollutant formation, models of combustion chemistry are needed that are sufficiently accurate to allow confident predic tions of flame structures. Reduced kinetic mechanisms, which are the topic of the present book, represent such combustion-chemistry models. Historically combustion chemistry was first described as a global one-step reaction in which fuel and oxidizer react to form a single product. Even when detailed mechanisms ofelementary reactions became available, empirical one step kinetic approximations were needed in order to make problems amenable to theoretical analysis. This situation began to change inthe early 1970s when computing facilities became more powerful and more widely available, thereby facilitating numerical analysis of relatively simple combustion problems, typi cally steady one-dimensional flames, with moderately detailed mechanisms of elementary reactions. However, even on the fastest and most powerful com puters available today, numerical simulations of, say, laminar, steady, three dimensional reacting flows with reasonably detailed and hence realistic ki netic mechanisms of elementary reactions are not possible.
Download or read book Combustion written by J. Warnatz and published by Springer Science & Business Media. This book was released on 1996 with total page 284 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 the 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 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 Fundamental and Semi global Kinetic Mechanisms of Hydrocarbon Combustion Annual Report October 1 1977 September 30 1978 written by and published by . This book was released on 1978 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Aimed at understanding practical combustion environments, present modeling efforts have been hampered by difficulties related to coupling combustion chemistry to the complex fluid mechanics present. In an attempt to circumvent such difficulties the present research program is aimed at the development of simplified chemical kinetic models (usually termed global models) to represent the combustion chemistry. Initially aimed at simple hydrocarbon fuels the program is progressing to studies of more complex aliphatics as well as important alternative fuels. The objective of this research is multifold: (a) to determine mechanistic oxidation routes of hydrocarbons derived from crudes and alternate sources, so that efficient and environmentally clean power plants based on internal and external combustion processes can be designed; (b) to develop and validate actual simplified (global) reaction rates for these hydrocarbons so that these power plants can be modelled; and (c) to develop an understanding of particulate (soot) formation to permit the rapid and successful introduction of the inexpensive, heavy, highly aromatic fuels. Studies of paraffin, olefin and alcohol hydrocarbons are reviewed. Appropriate global models are presented and compared with experimental data. The results clearly demonstrate that the turbulent flow reactor facility can be used to develop accurate global models for a variety of important fuels.
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 Applied Hydrocarbon Thermodynamics written by Wayne C. Edmister and published by Butterworth-Heinemann. This book was released on 1988 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Simplified Kinetic Schemes for the Oxidation of Hydrocarbon Fuels Using a Numerical Laminar Flame Model written by Ioannis C. Diakos and published by . This book was released on 1990 with total page 306 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Reduced Reaction Mechanisms for Numerical Calculations in Combustion of Hydrocarbon Fuels written by K. P. Kundu and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Fundamentals of Combustion Processes written by Sara McAllister and published by Springer Science & Business Media. This book was released on 2011-05-10 with total page 315 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fundamentals of Combustion Processes is designed as a textbook for an upper-division undergraduate and graduate level combustion course in mechanical engineering. The authors focus on the fundamental theory of combustion and provide a simplified discussion of basic combustion parameters and processes such as thermodynamics, chemical kinetics, ignition, diffusion and pre-mixed flames. The text includes exploration of applications, example exercises, suggested homework problems and videos of laboratory demonstrations
Download or read book Tackling Turbulent Flows in Engineering written by Anupam Dewan and published by Springer Science & Business Media. This book was released on 2010-10-23 with total page 129 pages. Available in PDF, EPUB and Kindle. Book excerpt: The emphasis of this book is on engineering aspects of fluid turbulence. The book explains for example how to tackle turbulence in industrial applications. It is useful to several disciplines, such as, mechanical, civil, chemical, aerospace engineers and also to professors, researchers, beginners, under graduates and post graduates. The following issues are emphasized in the book: - Modeling and computations of engineering flows: The author discusses in detail the quantities of interest for engineering turbulent flows and how to select an appropriate turbulence model; Also, a treatment of the selection of appropriate boundary conditions for the CFD simulations is given. - Modeling of turbulent convective heat transfer: This is encountered in several practical situations. It basically needs discussion on issues of treatment of walls and turbulent heat fluxes. - Modeling of buoyancy driven flows, for example, smoke issuing from chimney, pollutant discharge into water bodies, etc
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1990 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Reduced Kinetic Mechanisms and Asymptotic Approximations for Methane air Flames written by Mitchell D. Smooke and published by Springer. This book was released on 1991 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this comprehensive text a systematic numerical and analytical treatment of the procedures for reducing complicated systems to a simplified reaction mechanism is presented. The results of applying the reduced reaction mechanism to a one-dimensional laminar flame are discussed. A set of premixed and non-premixed methane-air flames with simplified transport and skeletal chemistry are employed as test problems that are used later on to evaluate the results and assumptions in reduced reaction networks. The first four chapters form a short tutorial on the procedures used in formulating the test problems and in reducing reaction mechanisms by applying steady-state and partial-equilibrium approximations. The final six chapters discuss various aspects of the reduced chemistry problem for premixed and nonpremixed combustion.
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 New Paradigm for Simplified Combustion Modeling of Energetic Solids written by and published by . This book was released on 1997 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: Two combustion models with simple but rational chemistry are compared: the classical high gas activation energy (E{sub g}/RT ≫ 1) Denison-Baum-Williams (DBW) model, and a new low gas activation energy (E{sub g}/RT ≪ 1) model recently proposed by Ward, Son, and Brewster (WSB). Both models make the same simplifying assumptions of constant properties, Lewis number unity, single-step, second order gas phase reaction, and single-step, zero order, high activation energy condensed phase decomposition. The only difference is in the gas reaction activation energy E{sub g} which is asymptotically large for DBW and vanishingly small for WSB. For realistic parameters the DBW model predicts a nearly constant temperature sensitivity?{sub p} and a pressure exponent n approaching 1. The WSB model predicts generally observed values of n = 0.7 to 0.9 and?{sub p}(T{sub o}, P) with the generally observed variations with temperature (increasing) and pressure (decreasing). The WSB temperature profile also matches measured profiles better. Comparisons with experimental data are made using HMX as an illustrative example (for which WSB predictions for?{sub p}(T{sub o}, P) are currently more accurate than even complex chemistry models). WSB has also shown good agreement with NC/NG double base propellant and HNF, suggesting that at the simplest level of combustion modeling, a vanishingly small gas activation energy is more realistic than an asymptotically large one. The authors conclude from this that the important (regression rate determining) gas reaction zone near the surface has more the character of chain branching than thermal decomposition.
