Reduction of the Detailed Kinetic Mechanism for Efficient Simulation of Ignition Delay for Mixtures of Methane and Acetylene with Oxygen

2020 ◽  
Vol 14 (6) ◽  
pp. 951-958
Author(s):  
A. M. Tereza ◽  
G. L. Agafonov ◽  
A. S. Betev ◽  
S. P. Medvedev
Keyword(s):  
Ignition Delay ◽  
Kinetic Mechanism ◽  
Efficient Simulation ◽  
Detailed Kinetic Mechanism

Ignition Characteristics of a Fischer-Tropsch Synthetic Jet Fuel

2008 ◽  
Author(s):  
P. Gokulakrishnan ◽  
M. S. Klassen ◽  
R. J. Roby
Keyword(s):  
Kinetic Model ◽  
Ignition Delay ◽  
Flow Reactor ◽  
Kinetic Mechanism ◽  
Jet Fuel ◽  
Synthetic Jet ◽  
Jet Fuels ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Ignition Characteristics

Ignition delay times of a “real” synthetic jet fuel (S8) were measured using an atmospheric pressure flow reactor facility. Experiments were performed between 900 K and 1200 K at equivalence ratios from 0.5 to 1.5. Ignition delay time measurements were also performed with JP8 fuel for comparison. Liquid fuel was prevaporized to gaseous form in a preheated nitrogen environment before mixing with air in the premixing section, located at the entrance to the test section of the flow reactor. The experimental data show shorter ignition delay times for S8 fuel than for JP8 due to the absence of aromatic components in S8 fuel. However, the ignition delay time measurements indicate higher overall activation energy for S8 fuel than for JP8. A detailed surrogate kinetic model for S8 was developed by validating against the ignition delay times obtained in the present work. The chemical composition of S8 used in the experiments consisted of 99.7 vol% paraffins of which approximately 80 vol% was iso-paraffins and 20% n-paraffins. The detailed kinetic mechanism developed in the current work included n-decane and iso-octane as the surrogate components to model ignition characteristics of synthetic jet fuels. The detailed surrogate kinetic model has approximately 700 species and 2000 reactions. This kinetic mechanism represents a five-component surrogate mixture to model generic kerosene-type jets fuels, namely, n-decane (for n-paraffins), iso-octane (for iso-paraffins), n-propylcyclohexane (for naphthenes), n-propylbenzene (for aromatics) and decene (for olefins). The sensitivity of iso-paraffins on jet fuel ignition delay times was investigated using the detailed kinetic model. The amount of iso-paraffins present in the jet fuel has little effect on the ignition delay times in the high temperature oxidation regime. However, the presence of iso-paraffins in synthetic jet fuels can increase the ignition delay times by two orders of magnitude in the negative temperature (NTC) region between 700 K and 900 K, typical gas turbine conditions. This feature can have a favorable impact on preventing flashback caused by the premature autoignition of liquid fuels in lean premixed prevaporized (LPP) combustion systems.

Ozone-Assisted Combustion—Part I: Literature Review and Kinetic Study Using Detailed n-Heptane Kinetic Mechanism

2014 ◽  
Vol 136 (9) ◽  
Author(s):  
Christopher Depcik ◽  
Michael Mangus ◽  
Colter Ragone
Keyword(s):  
Ignition Delay ◽  
Equivalence Ratio ◽  
Atomic Oxygen ◽  
Direct Injection ◽  
Kinetic Mechanism ◽  
Combustion Model ◽  
Ozone Decomposition ◽  
Compression Ignition ◽  
Review Of The Literature ◽  
Compression Ignition Engine

In this first paper, the authors undertake a review of the literature in the field of ozone-assisted combustion in order to summarize literature findings. The use of a detailed n-heptane combustion model including ozone kinetics helps analyze these earlier results and leads into experimentation within the authors' laboratory using a single-cylinder, direct-injection compression ignition engine, briefly discussed here and in more depth in a following paper. The literature and kinetic modeling outcomes indicate that the addition of ozone leads to a decrease in ignition delay, both in comparison to no added ozone and with a decreasing equivalence ratio. This ignition delay decrease as the mixture leans is counter to the traditional increase in ignition delay with decreasing equivalence ratio. Moreover, the inclusion of ozone results in slightly higher temperatures in the cylinder due to ozone decomposition, augmented production of nitrogen oxides, and reduction in particulate matter through radial atomic oxygen chemistry. Of additional importance, acetylene levels decrease but carbon monoxide emissions are found to both increase and decrease as a function of equivalence ratio. This work illustrates that, beyond a certain level of assistance (approximately 20 ppm for the compression ratio of the authors' engine), adding more ozone has a negligible influence on combustion and emissions. This occurs because the introduction of O3 into the intake causes a temperature-limited equilibrium set of reactions via the atomic oxygen radical produced.

Detailed kinetics of hydrogen abstraction from trans-decalin by OH radicals: the role of hindered internal rotation treatment

2020 ◽  
Vol 22 (44) ◽  
pp. 25740-25746
Author(s):  
Tam V.-T. Mai ◽  
Lam K. Huynh
Keyword(s):  
Master Equation ◽  
Hydrogen Abstraction ◽  
Kinetic Mechanism ◽  
Oh Radicals ◽  
Rate Model ◽  
Wide Range ◽  
Detailed Kinetics ◽  
Kinetics Of ◽  
Detailed Kinetic Mechanism

The detailed kinetic mechanism of the trans-decalin + OH reaction is firstly investigated for a wide range of conditions (T = 200–2000 K & P = 0.76–76000 Torr) using the M06-2X/aug-cc-pVTZ level and stochastic RRKM-based Master equation rate model.

Nitroalkanes as Reductive Substrates for Flavoprotein Oxidases

1972 ◽  
Vol 27 (9) ◽  
pp. 1052-1053 ◽  
Author(s):  
David J. T. Porter ◽  
Judith G. Voet ◽  
Harold J. Bright
Keyword(s):  
Hydrogen Peroxide ◽  
Amino Acid ◽  
Glucose Oxidase ◽  
Ph Dependence ◽  
Kinetic Mechanism ◽  
Acid Oxidase ◽  
Amino Acid Oxidase ◽  
Kinetics Of ◽  
Oxidase Reaction ◽  
Detailed Kinetic Mechanism

Nitroalkanes have been found to be general reductive substrates for D-amino acid oxidase, glucose oxidase and L-amino acid oxidase. These enzymes show different specificities for the structure of the nitroalkane substrate.The stoichiometry of the D-amino acid oxidase reaction is straightforward, consisting of the production of one mole each of aldehyde, nitrite and hydrogen peroxide for each mole of nitroalkane and oxygen consumed. The stoichiometry of the glucose oxidase reaction is more complex in that less than one mole of hydrogen peroxide and nitrite is produced and nitrate and traces of 1-dinitroalkane are formed.The kinetics of nitroalkane oxidation show that the nitroalkane anion is much more reactive in reducing the flavin than is the neutral substrate. The pH dependence of flavin reduction strongly suggests that proton abstraction is a necessary event in catalysis. A detailed kinetic mechanism is presented for the oxidation of nitroethane by glucose.It has been possible to trap a form of modified flavin in the reaction of D-amino acid oxidase with nitromethane from which oxidized FAD can be regenerated in aqueous solution in the presence of oxygen.

DNS on Autoignition and Flame Propagation of Inhomogeneous Methane–Air Mixtures in a Closed Vessel

2011 ◽  
Author(s):  
Makito Katayama ◽  
Naoya Fukushima ◽  
Masayasu Shimura ◽  
Mamoru Tanahashi ◽  
Toshio Miyauchi
Keyword(s):  
Heat Release ◽  
Flame Propagation ◽  
Heat Release Rate ◽  
Release Rate ◽  
Equivalence Ratio ◽  
Kinetic Mechanism ◽  
Spatial Inhomogeneity ◽  
Closed Vessel ◽  
Isothermal Wall ◽  
Detailed Kinetic Mechanism

Direct numerical simulations (DNSs) on autoignition and flame propagation of inhomogeneous methane–air mixtures in a closed vessel are conducted with considering detailed kinetic mechanism and temperature dependence of transport and thermal properties. The mixtures with spatial inhomogeneity of temperature or equivalence ratio are investigated. Periodic condition for non-heatloss cases or isothermal wall condition for heatloss cases is imposed on the boundaries. From the DNS results without heatloss, effects of spatial inhomogeneity of temperature and equivalence ratio on mean heat release rate are clarified. Increase of spatial variations of temperature or equivalence ratio suppresses drastic rise of mean heat release rate and reduces its maximum value. Autoignition process is affected by temperature more strongly than equivalence ratio. In the cases with heatloss, ignition delay increases and the maximum mean heat release rate decreases. After autoignition process, propagating flame is formed along walls. Heat transfer characteristics in a closed vessel are also discussed with combustion mechanisms.

A Numerical Study on the Low Limit Auto-Ignition Temperature of Syngas and Modification of Chemical Kinetic Mechanism

2019 ◽  
Author(s):  
Seung Eon Jang ◽  
Jin Park ◽  
Sang Hyeon Han ◽  
Hong Jip Kim ◽  
Ki Sung Jung ◽  
...  
Keyword(s):  
Low Temperature ◽  
Temperature Region ◽  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Numerical Results ◽  
Auto Ignition ◽  
Chemical Kinetic Mechanism

Abstract In this study, the auto ignition with low limit temperature of syngas has been numerically investigated using a 2-D numerical analysis. Previous study showed that auto ignition was observed at above 860 K in co-flow jet experiments using syngas and dry air. However, the auto ignition at this low temperature range could not be predicted with existing chemical mechanisms. Inconsistency of the auto ignition temperature between the experimental and numerical results is thought to be due to the inaccuracy of the chemical kinetic mechanism. The prediction of ignition delay time and sensitivity analysis for each chemical kinetic mechanism were performed to verify the reasons of the inconsistency between the experimental and numerical results. The results which were calculated using the various mechanisms showed significantly differences in the ignition delay time. In this study, we intend to analyze the reason of discrepancy to predict the auto ignition with low pressure and low temperature region of syngas and to improve the chemical kinetic mechanism. A sensitive analysis has been done to investigate the reaction steps which affected the ignition delay time significantly, and the reaction rate of the selected reaction step was modified. Through the modified chemical kinetic mechanism, we could identify the auto ignition in the low temperature region from the 2-D numerical results. Then CEMA (Chemical Explosive Mode Analysis) was used to validate the 2-D numerical analysis with modified chemical kinetic mechanism. From the validation, the calculated λexp, EI, and PI showed reasonable results, so we expect that the modified chemical kinetic mechanism can be used in various low temperature region.

Theoretical Investigation of Autoignition of Combustible Gas Mixtures in Rapid Compression Machines

2002 ◽  
Author(s):  
Shaoping Shi ◽  
Daniel Lee ◽  
Sandra McSurdy ◽  
Michael McMillian ◽  
Steven Richardson ◽  
...  
Keyword(s):  
Experimental Data ◽  
Theoretical Investigation ◽  
Ignition Delay ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Reaction Scheme ◽  
Independent Manner ◽  
Elementary Reactions ◽  
Chemical Kinetic Mechanism ◽  
Rapid Compression

In any theoretical investigation of ignition processes in natural gas reciprocating engines, physical and chemical mechanisms must be adequately modeled and validated in an independent manner. The Rapid Compression Machine (RCM) has been used in the past as a tool to validate both autoignition models as well as turbulent mixing effects. In this study, two experimental cases were examined. In the first experimental case, the experimental measurements of Lee and Hochgreb (1998a) were chosen to validate the simulation results. In their experiments, hydrogen/oxygen/argon mixtures were used as reactants. In the simulations, a reduced chemical kinetic mechanism consisting of 10 species and 19 elementary reactions coupled to a CFD software, Fluent 6, was used to simulate the autoignition. The ignition delay from the simulation agreed very well with that from the experimental data of Lee and Hochgreb, (1998b). In the second case, experimental data derived from an RCM with two opposed, pneumatically driven pistons (Brett et al., 2001) were used to study the autoignition of methane/oxygen/argon mixtures. The reduced chemical kinetic mechanism DRM22, derived from the GRI-Mech reaction scheme coupled to Fluent 6, was applied in the simulations. The DRM22 scheme included 22 species and 104 reactions. When methane/oxygen/argon mixture were simulated for the RCM, the ignition delay deviated about 15% from the experimental results. The simulation approaches as well as the validation results are discussed in detail in this paper. The paper also discusses an evaluation of reduced reaction models available in the literature for subsequent Fluent modeling.

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