Methyl formate oxidation: Speciation data, laminar burning velocities, ignition delay times, and a validated chemical kinetic model

2010 ◽  
Vol 42 (9) ◽  
pp. 527-549 ◽  
Author(s):  
S. Dooley ◽  
M. P. Burke ◽  
M. Chaos ◽  
Y. Stein ◽  
F. L. Dryer ◽  
...  
Keyword(s):  
Kinetic Model ◽  
Ignition Delay ◽  
Methyl Formate ◽  
Chemical Kinetic ◽  
Chemical Kinetic Model ◽  
Formate Oxidation ◽  
Ignition Delay Times ◽  
Delay Times

Reduced Chemical Kinetic Models of C1 - C4 Alcohols Using the Alternate Species Elimination Approach

2019 ◽  
Author(s):  
Apeng Zhou ◽  
Shirin Jouzdani ◽  
Ben Akih-Kumgeh
Keyword(s):  
Kinetic Models ◽  
Ignition Delay ◽  
Chemical Kinetic ◽  
Chemical Kinetic Model ◽  
Detailed Model ◽  
Elementary Reactions ◽  
Reduced Models ◽  
Ignition Delay Times ◽  
Combustion Properties ◽  
Delay Times

Abstract This study presents four separate reduced chemical kinetic models of methanol/ethanol, propanol isomers, n- and iso-butanol, and n- and s-butanol isomers, derived from a comprehensive chemical kinetic model of C1-C5 alcohols using the Alternate Species Elimination approach. It is motivated by complexity of the detailed model (comprising 600 species and 4100 elementary reactions) and the need for simpler kinetic models for analysis of combustion of smaller alcohols. The reduced models are obtained on the basis of ignition delay time simulations with imposed thresholds on the resulting normalized changes in ignition delay times. The following reduced models are obtained: methanol/ethanol: 38 species and 197 reactions; propanol isomers: 68 species and 419 reactions; n- and iso-butanol: 140 species and 745 reactions; and n- and s-butanol: 134 species and 739 reactions. Predictions of ignition delay times by the reduced models are found to be in good with the detailed models. The reduced models are further tested against other relevant combustion properties. These properties include burning velocities of laminar premixed flames, global pyrolysis time scales, and heat release timing in Homogeneous Charge Compression Ignition engines. This verification shows that reduced models can replace the comprehensive model in combustion analysis without loss of predictive performance. The reduced models can also serve as starting models for developing combined chemical kinetic models of gasoline/diesel and alcohol blends.

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.

Experimental Study on Ethane Ignition Delay Times and Evaluation of Chemical Kinetic Models

2015 ◽  
Vol 29 (7) ◽  
pp. 4557-4566 ◽  
Author(s):  
Erjiang Hu ◽  
Yizhen Chen ◽  
Zihang Zhang ◽  
Xiaotian Li ◽  
Yu Cheng ◽  
...  
Keyword(s):  
Experimental Study ◽  
Kinetic Models ◽  
Ignition Delay ◽  
Chemical Kinetic ◽  
Ignition Delay Times ◽  
Delay Times

scholarly journals Alternative Fuels Based on Biomass: An Experimental and Modeling Study of Ethanol Cofiring to Natural Gas

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Marina Braun-Unkhoff ◽  
Jens Dembowski ◽  
Jürgen Herzler ◽  
Jürgen Karle ◽  
Clemens Naumann ◽  
...  
Keyword(s):  
Power Generation ◽  
Natural Gas ◽  
Gas Turbine ◽  
Kinetic Modeling ◽  
Ignition Delay ◽  
Chemical Kinetic ◽  
Parameter Range ◽  
Ignition Delay Times ◽  
Combustion Properties ◽  
Delay Times

In response to the limited resources of fossil fuels as well as to their combustion contributing to global warming through CO2 emissions, it is currently discussed to which extent future energy demands can be satisfied by using biomass and biogenic by-products, e.g., by cofiring. However, new concepts and new unconventional fuels for electric power generation require a re-investigation of at least the gas turbine burner if not the gas turbine itself to ensure a safe operation and a maximum range in tolerating fuel variations and combustion conditions. Within this context, alcohols, in particular, ethanol, are of high interest as alternative fuel. Presently, the use of ethanol for power generation—in decentralized (microgas turbines) or centralized gas turbine units, neat, or cofired with gaseous fuels like natural gas (NG) and biogas—is discussed. Chemical kinetic modeling has become an important tool for interpreting and understanding the combustion phenomena observed, for example, focusing on heat release (burning velocities) and reactivity (ignition delay times). Furthermore, a chemical kinetic reaction model validated by relevant experiments performed within a large parameter range allows a more sophisticated computer assisted design of burners as well as of combustion chambers, when used within computational fluid dynamics (CFD) codes. Therefore, a detailed experimental and modeling study of ethanol cofiring to NG will be presented focusing on two major combustion properties within a relevant parameter range: (i) ignition delay times measured in a shock tube device, at ambient (p = 1 bar) and elevated (p = 4 bar) pressures, for lean (φ = 0.5) and stoichiometric fuel–air mixtures, and (ii) laminar flame speed data at several preheat temperatures, also for ambient and elevated pressure, gathered from literature. Chemical kinetic modeling will be used for an in-depth characterization of ignition delays and flame speeds at technical relevant conditions. An extensive database will be presented identifying the characteristic differences of the combustion properties of NG, ethanol, and ethanol cofired to NG.

Ignition and Flame Speed Kinetics of Two Natural Gas Blends With High Levels of Heavier Hydrocarbons

2008 ◽  
Author(s):  
Gilles Bourque ◽  
Darren Healy ◽  
Henry Curran ◽  
Christopher Zinner ◽  
Danielle Kalitan ◽  
...  
Keyword(s):  
High Pressure ◽  
Chemical Kinetics ◽  
Ignition Delay ◽  
Laminar Flame ◽  
Flame Speed ◽  
Data Set ◽  
Chemical Kinetic Model ◽  
Fuel Blends ◽  
Ignition Delay Times ◽  
Delay Times

High-pressure experiments and chemical kinetics modeling were performed to generate a database and a chemical kinetic model that can characterize the combustion chemistry of methane-based fuel blends containing significant levels of heavy hydrocarbons (up to 37.5% by volume). Ignition delay times were measured in two different shock tubes and in a rapid compression machine at pressures up to 34 atm and temperatures from 740 to 1660 K. Laminar flame speeds were also measured at pressures up to 4 atm using a high-pressure vessel with optical access. Two different fuel blends containing ethane, propane, n-butane, and n-pentane added to methane were studied at equivalence ratios varying from lean (0.3) to rich (2.0). This paper represents the most comprehensive set of experimental ignition and laminar flame speed data available in the open literature for CH4/C2H6/C3H8/C4H10/C5H12 fuel blends with significant levels of C2+ hydrocarbons. Using these data, a detailed chemical kinetics model, based on current and recent work by the authors, was compiled and refined. The predictions of the model are very good over the entire range of ignition delay times, considering the fact that the data set is so thorough. Nonetheless, some improvements to the model can still be made with respect to ignition times at the lowest temperatures and for the laminar flame speeds at pressures above 1 atm and rich conditions.

Investigation of Chemical Kinetic Model for Hypergolic Propellant of Monomethylhydrazine and Nitrogen Tetroxide

2020 ◽  
Vol 143 (6) ◽  
Author(s):  
Hu Hong-bo ◽  
Chen Hong-yu ◽  
Yan Yu ◽  
Zhang Feng ◽  
Yin Ji-Hui ◽  
...  
Keyword(s):  
Ignition Delay ◽  
Flame Temperature ◽  
Chemical Kinetic ◽  
Chemical Mechanism ◽  
Chamber Pressure ◽  
Nitrogen Tetroxide ◽  
Combustion Flame ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Calculation Results

Abstract Hypergolic bipropellant of monomethylhydrazine (MMH) and nitrogen tetroxide (NTO) is extensively used in spacecraft propulsion applications and rocket engines. But studies on the chemical kinetic mechanism of MMH/NTO are limited. So, in this study by integrating the submechanisms of MMH decomposition, NTO thermal decomposition, MMH/NTO and intermediates, and small hydrocarbons, the comprehensive chemical mechanism of MMH/NTO bipropellant is proposed. The present chemical mechanism consists of 72 species and 406 elementary reactions. In two respects of ignition delay times and combustion flame temperatures, the present model has been validated against the theoretical calculation results and also compared with other kinetic models in the literature. The validations show that the predicted ignition delay times by the present kinetic model are highly consistent with the theoretical data and well describe the pressure-dependent characteristic. For combustion flame temperature, the present model also exhibits better predictions to the theoretical calculation results, which are also the same as the predictions by the MMH-RFNA model. Furthermore, the influences of initial temperature, chamber pressure, and NTO/HHM mass ratio (O/F) on the ignition delay time and combustion flame temperature are investigated. The auto-ignition behavior of MMH/NTO propellant is sensitive to initial temperature and chamber pressure, and the combustion flame temperature is more sensitive to the O/F. This study provides a detail chemical kinetics model for further mechanism simplification and combustion numerical simulation.

CO Time-Histories During Oxy-Methane Combustion in a CO2 Environment

2019 ◽  
Author(s):  
Owen M. Pryor ◽  
Erik Ninnemann ◽  
Subith Vasu
Keyword(s):  
Carbon Monoxide ◽  
Ignition Delay ◽  
Methane Combustion ◽  
Chemical Kinetic ◽  
Tunable Diode Laser ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Kinetic Mechanisms ◽  
Time Histories ◽  
The Impact

Abstract Carbon monoxide time-histories and ignition delay times were measured in carbon dioxide diluted methane mixtures behind reflected shockwaves. Experiments were performed around 2 atm for a temperature range between 1650–2000 K. The experiments were performed for a mixture of XCH4 = 0.5%, XO2 = 1.0%, XCO2 = 8.5%, XAr = 90.0%. The mixture was chosen to minimize energy release during the experiment and a minimum of 2 ms was recorded for all experiments. The carbon monoxide time-histories were measured using a tunable diode laser absorption spectroscopy technique and measuring the absorbance at two different wavelengths to isolate the impact of carbon monoxide on the absorbance. Carbon monoxide was measured at a wavelength of 4886.94 nm while the interfering species was measured at 4891.17 nm. Each experiment was performed twice, with the pressure and temperature before combustion being matched to within the experimental uncertainty of the two experiments. The ignition delay times were measured using OH* radical emission to determine the time-scales of the experiments. All experiments were compared to detailed chemical kinetic mechanisms that can be found in the literature. The experimental results show that the detailed mechanisms from the literature were able to accurately predict the general profile of the carbon monoxide time-histories but under-predicted maximum concentration of CO being formed at these conditions.

Ignition Delay Times of Syngas and Methane in sCO2 Diluted Mixtures for Direct-Fired Cycles

2019 ◽  
Author(s):  
Samuel Barak ◽  
Owen Pryor ◽  
Erik Ninnemann ◽  
Sneha Neupane ◽  
Xijia Lu ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Ignition Delay ◽  
High Pressures ◽  
Chemical Kinetic ◽  
Time Data ◽  
Fuel Loading ◽  
Supercritical Regime ◽  
Reflected Shock ◽  
Ignition Delay Times ◽  
Delay Times

Abstract In this study, a shock tube is used to investigate combustion tendencies of several fuel mixtures under high carbon dioxide dilution and high fuel loading. Individual mixtures of oxy-syngas and oxy-methane fuels were added to CO2 bath gas environments and ignition delay time data was recorded. Reflected shock pressures maxed around 100 atm, which is above the critical pressure of carbon dioxide in to the supercritical regime. In total, five mixtures were investigated within a temperature range of 1050–1350K. Ignition delay times of all mixtures were compared with predictions of two leading chemical kinetic computer mechanisms for accuracy. The mixtures included four oxy-syngas and one oxy-methane combinations. The experimental data tended to show good agreement with the predictions of literature models for the methane mixture. For all syngas mixtures though the models performed reasonably well at some conditions, predictions were not able to accurately capture the overall behavior. For this reason, there is a need to further investigate the discrepancies in predictions. Additionally, more data must be collected at high pressures to fully understand the chemical kinetic behavior of these mixtures to enable the supercritical CO2 power cycle development.

Chemical Kinetic Model Reduction and Analysis of Tetrahydrofuran Combustion Using Stochastic Species Elimination

2020 ◽  
Author(s):  
Mazen A. Eldeeb ◽  
Malshana Wadugurunnehalage
Keyword(s):  
Kinetic Model ◽  
Model Reduction ◽  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Laminar Flame ◽  
Chemical Kinetic ◽  
Reduced Model ◽  
Chemical Kinetic Model ◽  
Parameter Modification

Abstract In this work, a chemical kinetic modeling study of the high-temperature ignition and laminar flame behavior of Tetrahydrofuran (THF), a promising second-generation transportation biofuel, is presented. Stochastic Species Elimination (SSE) model reduction approach (Eldeeb and Akih-Kumgeh, Proceedings of ASME Power Conference 2018) is implemented to develop multiple skeletal versions of a detailed chemical kinetic model of THF (Fenard et al., Combustion and Flame, 2018) based on ignition delay time simulations at various pressures and temperature ranges. The detailed THF model contains 467 species and 2390 reactions. The developed skeletal versions are combined into an overall reduced model of THF, consisting of 193 species and 1151 reactions. Ignition delay time simulations are performed using detailed and reduced models, with varying levels of agreement observed at most conditions. Sensitivity analysis is then performed to identify the most important reactions responsible for the observed performance of the reduced model. Reaction rate parameter modification is performed for such reactions in order to improve the agreement of detailed and reduced model predictions with literature experimental ignition data. The work contributes toward improved understanding and modeling of the oxidation kinetics of potential transportation biofuels, especially cyclic ethers.

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