scholarly journals Reduced Chemical Kinetic Reaction Mechanism for Dimethyl Ether-Air Combustion

Fuels ◽  
2021 ◽  
Vol 2 (3) ◽  
pp. 323-344
Author(s):  
Niklas Zettervall ◽  
Christer Fureby ◽  
Elna J. K. Nilsson
Keyword(s):  
Experimental Data ◽  
Reaction Mechanism ◽  
Dimethyl Ether ◽  
Burning Velocity ◽  
Negative Temperature ◽  
Chemical Kinetic ◽  
Ignition Delay Times ◽  
Wide Range ◽  
Combustion Simulation ◽  
Base Mechanism

Development and validation of a new reduced dimethyl ether-air (DME) reaction mechanism is presented. The mechanism was developed using a modular approach that has previously been applied to several alkane and alkene fuels, and the present work pioneers the use of the modular methodology, with its underlying H/C1/O base mechanism, on an oxygenated fuel. The development methodology uses a well-characterized H/C1/O base mechanism coupled to a reduced set of fuel and intermediate product submechanisms. The mechanism for DME presented in this work includes 30 species and 69 irreversible reactions. When used in combustion simulation the mechanism accurately reproduced key combustion characteristics and the small size enables use in computationally demanding Large Eddy Simulations (LES) and Direct Numerical Simulations (DNS). It has been developed to accurately predict, among other parameters, laminar burning velocity and ignition delay times, including the negative temperature regime. The evaluation of the mechanism and comparison to experimental data and several detailed and reduced mechanisms covers a wide range of conditions with respect to temperature, pressure and fuel-to-air ratio. There is good agreement with experimental data and the detailed reference mechanisms at all investigated conditions. The mechanism uses fewer reactions than any previously presented DME-air mechanism, without losing in predictability.

Reaction Model Development of Selected Aromatics as Relevant Molecules of a Kerosene Surrogate – The Importance of M-Xylene Within the Combustion of 1,3,5-Trimethylbenzene

2021 ◽  
Author(s):  
Astrid Ramirez Hernandez ◽  
Trupti Kathrotia ◽  
Torsten Methling ◽  
Marina Braun-Unkhoff ◽  
Uwe Riedel
Keyword(s):  
Atmospheric Pressure ◽  
Burning Velocity ◽  
Model Development ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Reaction Model ◽  
Pollutant Emissions ◽  
Similar Species ◽  
Ignition Delay Times ◽  
Wide Range

Abstract The development of advanced reaction models to predict pollutant emissions in aero-engine combustors usually relies on surrogate formulations of a specific jet fuel for mimicking its chemical composition. 1,3,5-trimethylbenzene is one of the suitable components to represent aromatics species in those surrogates. However, a comprehensive reaction model for 1,3,5-trimethylbenzene combustion requires a mechanism to describe the m-xylene oxidation. In this work, the development of a chemical kinetic mechanism for describing the m-xylene combustion in a wide parameter range (i.e. temperature, pressure, and fuel equivalence ratios) is presented. The m-xylene reaction submodel was developed based on existing reaction mechanisms of similar species such as toluene and reaction pathways adapted from literature. The sub-model was integrated into an existing detailed mechanism that contains the kinetics of a wide range of n-paraffins, iso-paraffins, cyclo-paraffins, and aromatics. Simulation results for m-xylene were validated against experimental data available in literature. Results show that the presented m-xylene mechanism correctly predicts ignition delay times at different pressures and temperatures as well as laminar burning velocities at atmospheric pressure and various fuel equivalence ratios. At high pressure, some deviations of the calculated laminar burning velocity and the measured values are obtained at stoichiometric to rich equivalence ratios. Additionally, the model predicts reasonably well concentration profiles of major and intermediate species at different temperatures and atmospheric pressure.

Reaction Model Development of Selected Aromatics as Relevant Molecules of a Kerosene Surrogate - The Importance of M-Xylene within the Combustion of 1,3,5-trimethylbenzene

2021 ◽  
Author(s):  
Astrid Yuliana Ramirez Hernandez ◽  
Trupti Kathrotia ◽  
Torsten Methling ◽  
Marina Braun-Unkhoff ◽  
Uwe Riedel
Keyword(s):  
Atmospheric Pressure ◽  
Burning Velocity ◽  
Model Development ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Reaction Model ◽  
Pollutant Emissions ◽  
Similar Species ◽  
Ignition Delay Times ◽  
Wide Range

Abstract The development of advanced reaction models to predict pollutant emissions in aero-engine combustors usually relies on surrogate formulations of a specific jet fuel for mimicking its chemical composition. 1,3,5-trimethylbenzene is one of the suitable components to represent aromatics species in those surrogates. However, a comprehensive reaction model for 1,3,5-trimethylbenzene combustion requires a mechanism to describe the m-xylene oxidation. In this work, the development of a chemical kinetic mechanism for describing the m-xylene combustion in a wide parameter range (i.e. temperature, pressure, and fuel equivalence ratios) is presented. The m-xylene reaction sub-model was developed based on existing reaction mechanisms of similar species such as toluene and reaction pathways adapted from literature. The sub-model was integrated into an existing detailed mechanism that contains the kinetics of a wide range of n-paraffins, iso-paraffins, cyclo-paraffins, and aromatics. Simulation results for m-xylene were validated against experimental data available in literature. Results show that the presented m-xylene mechanism correctly predicts ignition delay times at different pressures and temperatures as well as laminar burning velocities at atmospheric pressure and various fuel equivalence ratios. At high pressure, some deviations of the calculated laminar burning velocity and the measured values are obtained at stoichiometric to rich equivalence ratios. Additionally, the model predicts reasonably well concentration profiles of major and intermediate species at different temperatures and atmospheric pressure.

Combustion Simulation of Propane/Oxygen (With Nitrogen/Argon) Mixtures Using Rate-Controlled Constrained-Equilibrium

2018 ◽  
Vol 141 (2) ◽  
Author(s):  
Guangying Yu ◽  
Hameed Metghalchi ◽  
Omid Askari ◽  
Ziyu Wang
Keyword(s):  
Experimental Data ◽  
Energy System ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Oxygen Mixture ◽  
Free Valence ◽  
Wide Range ◽  
Constrained Equilibrium ◽  
Rate Controlled ◽  
Good Agreement

The rate-controlled constrained-equilibrium (RCCE), a model order reduction method, has been further developed to simulate the combustion of propane/oxygen mixture diluted with nitrogen or argon. The RCCE method assumes that the nonequilibrium states of a system can be described by a sequence of constrained-equilibrium states subject to a small number of constraints. The developed new RCCE approach is applied to the oxidation of propane in a constant volume, constant internal energy system over a wide range of initial temperatures and pressures. The USC-Mech II (109 species and 781 reactions, without nitrogen chemistry) is chosen as chemical kinetic mechanism for propane oxidation for both detailed kinetic model (DKM) and RCCE method. The derivation for constraints of propane/oxygen mixture starts from the eight universal constraints for carbon-fuel oxidation. The universal constraints are the elements (C, H, O), number of moles, free valence, free oxygen, fuel, and fuel radicals. The full set of constraints contains eight universal constraints and seven additional constraints. The results of RCCE method are compared with the results of DKM to verify the effectiveness of constraints and the efficiency of RCCE. The RCCE results show good agreement with DKM results under different initial temperature and pressures, and RCCE also reduces at least 60% CPU time. Further validation is made by comparing the experimental data; RCCE shows good agreement with shock tube experimental data.

Investigating Trends in Simulated Ignition Timing Across a Wide Range of Conditions Including Fuel Reactivity

2012 ◽  
Author(s):  
Michael V. Johnson ◽  
S. Scott Goldsborough ◽  
Timothy A. Smith ◽  
Steven S. McConnell
Keyword(s):  
Ignition Delay ◽  
Equivalence Ratio ◽  
Computational Cost ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Ignition Timing ◽  
Ignition Delay Times ◽  
Wide Range ◽  
Initial Work ◽  
Ci Engines

Continued interest in kinetically-modulated combustion regimes, such as HCCI and PCCI, poses a significant challenge in controlling the ignition timing due to the lack of direct control of combustion phasing hardware available in traditional SI and CI engines. Chemical kinetic mechanisms, validated based on fundamental data from experiments like rapid compression machines and shock tubes, offer reasonably accurate predictions of ignition timing; however utilizing these requires high computational cost making them impractical for use in engine control schemes. Empirically-derived correlations offer faster control, but are generally not valid beyond the narrow range of conditions over which they were derived. This study discusses initial work in the development of an ignition correlation based on a detailed chemical kinetic mechanism for three component gasoline surrogate, composed of n-heptane, iso-octane and toluene, or toluene reference fuel (TRF). Simulations are conducted over a wide range of conditions including temperature, pressure, equivalence ratio and dilution for a range of tri-component blends in order to produce ignition delay time and investigate trends in ignition as pressure, equivalence ratio, temperature and fuel reactivity are varied. A modified, Arrhenius-based power law formulation will be used in a future study to fit the computed ignition delay times.

Development of a Detailed JP-8/Jet-A Chemical Kinetic Mechanism for High Pressure Conditions in Gas Turbine Combustors

2006 ◽  
Author(s):  
M. A. Mawid ◽  
B. Sekar
Keyword(s):  
High Pressure ◽  
Reaction Mechanism ◽  
Chemical Kinetic ◽  
Reflected Shock Wave ◽  
Kinetic Rate ◽  
Kinetic Reaction ◽  
Reflected Shock ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Pressure Independent

Pressure conditions under which chemical reactions proceed in gas turbine combustors impact the behavior of the combustion process by either increasing or decreasing the reaction rates depending on whether these reactions are unimolecular/recombination or chemically activated bimolecular reactions. Some reactions are pressure independent such as H-abstraction reactions, while others are conditionally pressure independent if they are not at their either low or high limits. The recombination and decomposition of kinetic reactions rate constants change relative to their limiting values as the pressure and/or temperature conditions vary and as a result the reactants concentrations and reactions pathways are also influenced. In this study, pressure-dependent kinetic rate parameters for 39 elementary reactions have been added to our detailed JP-8/Jet-A kinetic reaction mechanism, we have developed [1–3, 23, 58], to model ignition of JP-8 and Jet-A fuels behind a reflected shock wave. The main objective is to develop a detailed chemical kinetic reaction mechanism for low and high pressure combustion conditions, using a 6-component surrogate fuel blend considered to represent the actual (petroleum-derived) JP-8 and Jet-A fuels. The pressure-dependent kinetic rate parameters for 39 reactions have been incorporated into our low pressure detailed JP-8 chemical kinetic reaction mechanism to generate the fall-off curves for the Arrehnius rate parameters required for low and high pressure ignition analysis. The new JP-8 detailed mechanism has been evaluated, using a stoichiometric JP-8/02/N2 and Jet-A/air mixtures, over a temperature range of 968–1639 K and a pressure range of 10 to 34 atmosphere by predicting auto-ignition delay times and comparing them to the shock tube ignition data of Minsk, Sarikovskii, and Hanson [56]. The results indicated that the developed JP-8/Jet-A reaction mechanism is capable of reproducing the qualitative ignition trends of the measured ignition data behind a reflected shock wave. However, the detailed kinetic reaction mechanism overestimated the measured ignition delay times. The results also suggested that additional more reactions are high pressure-dependent under the conditions considered in this study and as such a need still exists for experimentally measured kinetic rate coefficients for high pressure ignition and combustion conditions. This study, therefore, warrants further experiments and detailed kinetic analysis.

scholarly journals Chemical Kinetic Mechanism Study on Premixed Combustion of Ammonia/Hydrogen Fuels for Gas Turbine Use

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Hua Xiao ◽  
Agustin Valera-Medina
Keyword(s):  
Experimental Data ◽  
Gas Turbine ◽  
Ignition Delay ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Sensitivity Analyses ◽  
Mechanism Study ◽  
Combustion Chemistry ◽  
Chemical Mechanisms ◽  
Ignition Delay Times

To explore the potential of ammonia-based fuel as an alternative fuel for future power generation, studies involving robust mathematical, chemical, thermofluidic analyses are required to progress toward industrial implementation. Thus, the aim of this study is to identify reaction mechanisms that accurately represent ammonia kinetics over a large range of conditions, particularly at industrial conditions. To comprehensively evaluate the performance of the chemical mechanisms, 12 mechanisms are tested in terms of flame speed, NOx emissions and ignition delay against the experimental data. Freely propagating flame calculations indicate that Mathieu mechanism yields the best agreement within experimental data range of different ammonia concentrations, equivalence ratios, and pressures. Ignition delay times calculations show that Mathieu mechanism and Tian mechanism yield the best agreement with data from shock tube experiments at pressures up to 30 atm. Sensitivity analyses were performed in order to identify reactions and ranges of conditions that require optimization in future mechanism development. The present study suggests that the Mathieu mechanism and Tian mechanism are the best suited for the further study on ammonia/hydrogen combustion chemistry under practical industrial conditions. The results obtained in this study also allow gas turbine designers and modelers to choose the most suitable mechanism for combustion studies.

Auto Ignition Study of Methane and Bio Alcohol Fuel Blends

2019 ◽  
Vol 141 (12) ◽  
Author(s):  
Xuan Zheng ◽  
Shirin Jouzdani ◽  
Benjamin Akih-Kumgeh
Keyword(s):  
Experimental Data ◽  
Kinetic Models ◽  
Ignition Delay ◽  
Chemical Kinetic ◽  
Dual Fuel ◽  
Fuel Blends ◽  
Ignition Delay Times ◽  
Auto Ignition ◽  
Alcohol Fuel ◽  
Delay Times

Abstract Methane (CH4) and bio alcohols have different ignition properties. These have been extensively studied and the resulting experimental data have been used to validate chemical kinetic models. Methane is the main component of natural gas, which is of interest because of its relative availability and lower emissions compared to other hydrocarbon fuels. Given growing interest in fuel-flexible systems, there can be situations in which the combustion properties of natural gas need to be modified by adding biofuels such as bio alcohols. This can occur in dual-fuel internal combustion engines or gas turbines with dual-fuel capabilities. The combustion behavior of such blends can be understood by studying the auto ignition properties in fundamental combustion experiments. Studies of the ignition of such blends are very limited in the literature. In this work, the auto ignition of methane and bio alcohol fuel blends is investigated using a shock tube facility. The chosen bio alcohols are ethanol (C2H5OH) and n-propanol (NC3H7OH). Experiments are carried out at 3 atm and 10 atm for stoichiometric and lean mixtures of fuel, oxygen, and argon. The ignition delay times of the pure fuels are first established at conditions of constant oxygen concentration and comparable pressures. The ignition delay times of blends with 50% methane are then measured. The pyrolysis kinetics of the blends is further explored by measuring CO formation during pyrolysis of the alcohol and methane–alcohol blends. The resulting experimental data are compared with the predictions of selected chemical kinetic models to establish the ability of these models to predict the disproportionate enhancement of methane ignition by the added alcohol.

Auto Ignition Study of Methane and Bio Alcohol Fuel Blends

2019 ◽  
Author(s):  
Xuan Zheng ◽  
Shirin Jouzdani ◽  
Benjamin Akih-Kumgeh
Keyword(s):  
Experimental Data ◽  
Kinetic Models ◽  
Ignition Delay ◽  
Chemical Kinetic ◽  
Dual Fuel ◽  
Fuel Blends ◽  
Ignition Delay Times ◽  
Auto Ignition ◽  
Alcohol Fuel ◽  
Delay Times

Abstract Methane (CH4) and bio alcohols have different ignition properties. These have been extensively studied and the resulting experimental data have been used to validate chemical kinetic models. Methane is the main component of natural gas, which is of interest because of its relative availability and lower emissions compared to other hydrocarbon fuels. Given growing interest in fuel-flexible systems, there can be situations in which the combustion properties of natural gas need to be modified by adding biofuels, such as bio alcohols. This can occur in dual fuel internal combustion engines or gas turbines with dual fuel capabilities. The combustion behavior of such blends can be understood by studying the auto ignition properties in fundamental combustion experiments. Studies of the ignition of such blends are very limited in the literature. In this work, the auto ignition of methane and bio alcohol fuel blends is investigated using a shock tube facility. The chosen bio alcohols are ethanol (C2H5OH) and n-propanol (NC3H7OH). Experiments are carried out at 3 atm and 10 atm for stoichiometric and lean mixtures of fuel, oxygen, and argon. The ignition delay times of the pure fuels are first established at conditions of constant oxygen concentration and comparable pressures. The ignition delay times of blends with 50% methane are then measured. The pyrolysis kinetics of the blends is further explored by measuring CO formation during pyrolysis of the alcohol and methane-alcohol blends. The resulting experimental data are compared with the predictions of selected chemical kinetic models to establish the ability of these models to predict the disproportionate enhancement of methane ignition by the added alcohol.

Prediction of Premixed Laminar Flame Structure and Burning Velocity of Aviation Fuel-Air Mixtures

2001 ◽  
Author(s):  
A. G. Kyne ◽  
P. M. Patterson ◽  
M. Pourkashanian ◽  
C. W. Wilson ◽  
A. Williams
Keyword(s):  
Reaction Mechanism ◽  
Laminar Flame ◽  
Burning Velocity ◽  
Flame Structure ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Aviation Fuel ◽  
Measured Temperature ◽  
Premixed Laminar ◽  
Increasing Temperature

The structure of a rich burner stabilised kerosene/O2/N2 flame is predicted using a detailed chemical kinetic mechanism where the kerosene is represented by a mixture of n-decane and toluene. The chemical reaction mechanism, consisting of 440 reactions between 84 species, is capable of predicting the experimentally determined flame structure of Douté et al. (1995) with good success using the measured temperature profile as input. Sensitivity and reaction rate analyses are carried out to identify the most significant reactions and based on this the reaction mechanism was reduced to one with only 165 reactions without any loss of accuracy. Burning velocities of kerosene-air mixtures were also determined over an extensive range of equivalence ratios at atmospheric pressure. The initial temperature of the mixture was also varied and burning velocities were found to increase with increasing temperature. Burning velocities calculated using both the detailed and reduced mechanisms were essentially identical.

Theoretical Prediction of Laminar Burning Speed and Ignition Delay of Gas to Liquid Fuel

2016 ◽  
Author(s):  
Guangying Yu ◽  
Omid Askari ◽  
Fatemeh Hadi ◽  
Ziyu Wang ◽  
Hameed Metghalchi ◽  
...  
Keyword(s):  
Chemical Kinetics ◽  
Ignition Delay ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Ignition Delay Times ◽  
Wide Range ◽  
Delay Times ◽  
Chemical Kinetic Mechanism ◽  
Gas To Liquid ◽  
Laminar Burning Speed

Gas to Liquid (GTL), an alternative synthetic jet fuel derived from natural gas has gained significant attention recently due to its cleaner combustion characteristics when compared to conventional counterparts. The effect of chemical composition on key performance aspects such as ignition delay time, laminar burning speed, and emission characteristics have been experimentally studied. However, the development of chemical kinetics mechanism to predict those parameters for GTL fuel is still in its early stage. In this work, a detailed kinetics model (DKM) has been developed based on the chemical kinetics reported for GTL surrogate fuels. The DKM is applied to the chemical kinetic mechanism of 597 species and 3853 reactions. The DKM is employed in a constant internal energy and constant volume reactor to predict the ignition delay times for GTL and its three surrogates over a wide range of initial temperature, pressure and equivalence ratio. The ignition delay times predicted using DKM are validated with those reported in the literature. Furthermore, the CANTERA freely propagating 1D flame code is used in conjunction with the chemical kinetic mechanism to predict the laminar burning speeds for GTL fuel over a wide range of operating conditions.

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