scholarly journals Comparative Study on Chemical Kinetics Mechanisms for Methane-Based Fuel Mixtures under Engine-Relevant Conditions

Energies ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2834
Author(s):  
Amin Paykani
Keyword(s):  
Experimental Data ◽  
Natural Gas ◽  
Chemical Kinetics ◽  
Ignition Delay ◽  
High Pressures ◽  
Laminar Flame ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Si Engine ◽  
Fuel Blends

The use of natural gas in pure or in a blended form with hydrogen and syngas in spark ignition (SI) engines has received much attention in recent years. They have higher diffusion coefficient and laminar flame speed, a small quenching distance and wider flammability limit which compensate the demerits of the lean-burn natural gas combustion. Therefore, a careful examination of the chemical kinetics of combustion of gaseous fuel blends is of great importance. In this paper, performance of the various chemical kinetics mechanisms is compared against experimental data, accumulated for methane-based fuel blends under engine-relevant conditions to find the most appropriate mechanism in engine simulations. Pure methane, methane/syngas, and methane/propane blends are mainly studied at various temperatures, pressures, and equivalence ratios. The ignition delay time and laminar flame speed are used as quantitative metrics to compare the simulation results with the data from experiments. The mechanisms were shown to be mainly consistent with the experimental data of lean and stoichiometric mixtures at high pressures. It was also shown that the GRI-3.0 and 290Rxn mechanisms have high compatibility with the ignition delay times and laminar flame speed at high pressures and lean conditions, and they can be utilized for simulations of SI engine combustion due to their lower computational cost. The results of present research provide an important contribution to the methane-based fuel blends combustion simulation under SI engine-relevant conditions.

Ignition Delay Time and Laminar Flame Speed Calculations for Natural Gas/Hydrogen Blends at Elevated Pressures

2012 ◽  
Author(s):  
Marissa Brower ◽  
Eric Petersen ◽  
Wayne Metcalfe ◽  
Henry J. Curran ◽  
Marc Füri ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Chemical Kinetics ◽  
Ignition Delay ◽  
Ignition Delay Time ◽  
Laminar Flame ◽  
Turbulent Flame ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Hydrogen Addition

Applications of natural gas and hydrogen co-firing have received increased attention in the gas turbine market, which aims at higher flexibility due to concerns over the availability of fuels. While much work has been done in the development of a fuels database and corresponding chemical kinetics mechanism for natural gas mixtures, there are nonetheless few if any data for mixtures with high levels of hydrogen at conditions of interest to gas turbines. The focus of the present paper is on gas turbine engines with primary and secondary reaction zones as represented in the Alstom and Rolls Royce product portfolio. The present effort includes a parametric study, a gas turbine model study, and turbulent flame speed predictions. Using a highly optimized chemical kinetics mechanism, ignition delay times and laminar burning velocities were calculated for fuels from pure methane to pure hydrogen and with natural gas/hydrogen mixtures. A wide range of engine-relevant conditions were studied: pressures from 1 to 30 atm, flame temperatures from 1600 to 2200 K, primary combustor inlet temperature from 300 to 900 K, and secondary combustor inlet temperatures from 900 to 1400 K. Hydrogen addition was found to increase the reactivity of hydrocarbon fuels at all conditions by increasing the laminar flame speed and decreasing the ignition delay time. Predictions of turbulent flame speeds from the laminar flame speeds show that hydrogen addition affects the reactivity more when turbulence is considered. This combined effort of industrial and university partners brings together the know-how of applied, as well as experimental and theoretical disciplines.

scholarly journals Investigation of the Effect of Hydrogen and Methane on Combustion of Multicomponent Syngas Mixtures using a Constructed Reduced Chemical Kinetics Mechanism

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2442 ◽  
Author(s):  
Nearchos Stylianidis ◽  
Ulugbek Azimov ◽  
Martin Birkett
Keyword(s):  
Chemical Kinetics ◽  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
High Pressures ◽  
Laminar Flame ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
The Difference ◽  
Rich Mixtures

This study investigated the effects of H2 and CH4 concentrations on the ignition delay time and laminar flame speed during the combustion of CH4/H2 and multicomponent syngas mixtures using a novel constructed reduced syngas chemical kinetics mechanism. The results were compared with experiments and GRI Mech 3.0 mechanism. It was found that mixture reactivity decreases and increases when higher concentrations of CH4 and H2 were used, respectively. With higher H2 concentration in the mixture, the formation of OH is faster, leading to higher laminar flame speed and shorter ignition delay time. CH4 and H2 concentrations were calculated at different pressures and equivalence ratios, showing that at high pressures CH4 is consumed slower, and, at different equivalence ratios CH4 reacts at different temperatures. In the presence of H2, CH4 was consumed faster. In the conducted two-stage sensitivity analysis, the first analysis showed that H2/CH4/CO mixture combustion is driven by H2-based reactions related to the consumption/formation of OH and CH4 recombination reactions are responsible for CH4 oxidation. The second analysis showed that similar CH4-based and H2 -based reactions were sensitive in both, methane- and hydrogen-rich H2/CH4 mixtures. The difference was observed for reactions CH2O + OH = HCO + H2O and CH4 + HO2 = CH3 + H2O2, which were found to be important for CH4-rich mixtures, while reactions OH + HO2 = H2O + O2 and HO2 + H = OH + OH were found to be important for H2-rich mixtures.

Ignition Delay Time and Laminar Flame Speed Calculations for Natural Gas/Hydrogen Blends at Elevated Pressures

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Marissa Brower ◽  
Eric L. Petersen ◽  
Wayne Metcalfe ◽  
Henry J. Curran ◽  
Marc Füri ◽  
...  
Keyword(s):  
Natural Gas ◽  
Gas Turbine ◽  
Chemical Kinetics ◽  
Ignition Delay ◽  
Ignition Delay Time ◽  
Laminar Flame ◽  
Turbulent Flame ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Hydrogen Addition

Applications of natural gas and hydrogen co-firing have received increased attention in the gas turbine market, which aims at higher flexibility due to concerns over the availability of fuels. While much work has been done in the development of a fuels database and corresponding chemical kinetics mechanism for natural gas mixtures, there are nonetheless few if any data for mixtures with high levels of hydrogen at conditions of interest to gas turbines. The focus of the present paper is on gas turbine engines with primary and secondary reaction zones as represented in the Alstom and Rolls Royce product portfolio. The present effort includes a parametric study, a gas turbine model study, and turbulent flame speed predictions. Using a highly optimized chemical kinetics mechanism, ignition delay times and laminar burning velocities were calculated for fuels from pure methane to pure hydrogen and with natural gas/hydrogen mixtures. A wide range of engine-relevant conditions were studied: pressures from 1 to 30 atm, flame temperatures from 1600 to 2200 K, primary combustor inlet temperature from 300 to 900 K, and secondary combustor inlet temperatures from 900 to 1400 K. Hydrogen addition was found to increase the reactivity of hydrocarbon fuels at all conditions by increasing the laminar flame speed and decreasing the ignition delay time. Predictions of turbulent flame speeds from the laminar flame speeds show that hydrogen addition affects the reactivity more when turbulence is considered. This combined effort of industrial and university partners brings together the know-how of applied as well as experimental and theoretical disciplines.

Laminar Flame Speed and Ignition Delay Time Data for the Kinetic Modeling of Hydrogen and Syngas Fuel Blends

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Michael C. Krejci ◽  
Olivier Mathieu ◽  
Andrew J. Vissotski ◽  
Sankaranarayanan Ravi ◽  
Travis G. Sikes ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Chemical Kinetics ◽  
Ignition Delay ◽  
Laminar Flame ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Elevated Pressures ◽  
Ignition Delay Times ◽  
Wide Range ◽  
Delay Times

Laminar flame speeds and ignition delay times have been measured for hydrogen and various compositions of H2/CO (syngas) at elevated pressures and elevated temperatures. Two constant-volume cylindrical vessels were used to visualize the spherical growth of the flame through the use of a schlieren optical setup to measure the laminar flame speed of the mixture. Hydrogen experiments were performed at initial pressures up to 10 atm and initial temperatures up to 443 K. A syngas composition of 50/50 by volume was chosen to demonstrate the effect of carbon monoxide on H2-O2 chemical kinetics at standard temperature and pressures up to 10 atm. All atmospheric mixtures were diluted with standard air, while all elevated-pressure experiments were diluted with a He:O2 ratio of 7:1 to minimize instabilities. The laminar flame speed measurements of hydrogen and syngas are compared to available literature data over a wide range of equivalence ratios, where good agreement can be seen with several data sets. Additionally, an improved chemical kinetics model is shown for all conditions within the current study. The model and the data presented herein agree well, which demonstrates the continual, improved accuracy of the chemical kinetics model. A high-pressure shock tube was used to measure ignition delay times for several baseline compositions of syngas at three pressures across a wide range of temperatures. The compositions of syngas (H2/CO) by volume presented in this study included 80/20, 50/50, 40/60, 20/80, and 10/90, all of which are compared to previously published ignition delay times from a hydrogen-oxygen mixture to demonstrate the effect of carbon monoxide addition. Generally, an increase in carbon monoxide increases the ignition delay time, but there does seem to be a pressure dependency. At low temperatures and pressures higher than about 12 atm, the ignition delay times appear to be indistinguishable with an increase in carbon monoxide. However, at high temperatures the relative composition of H2 and CO has a strong influence on ignition delay times. Model agreement is good across the range of the study, particularly at the elevated pressures.

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.

scholarly journals Effects of oil and water contamination on natural gas engine combustion processes

2017 ◽  
Author(s):  
Shyam Menon ◽  
Himakar Ganti ◽  
Kyle Evan Niemeyer ◽  
Christopher Hagen
Keyword(s):  
Natural Gas ◽  
Ignition Delay ◽  
Laminar Flame ◽  
Combustion Process ◽  
Flame Speed ◽  
Slight Reduction ◽  
Laminar Flame Speed ◽  
Autoignition Temperature ◽  
Engine Combustion ◽  
Combustion Processes

Abundant availability and potential for lower emissions are drivers for increased utilization of natural gas in automotive engines for transportation applications. A novel bimodal engine has been developed that allows on-board refueling of natural gas by utilizing the engine as a compressor. Engine compression however, results in altering the initial state of the natural gas. Increase in temperature and addition of oil are two key effects attributed to the onboard refueling process. A secondary effect is the presence of water in the natural gas supply line. This study investigates the effect of upstream conditions of natural gas on three parameters: autoignition temperature, ignition delay, and laminar flame speed. These parameters play key roles in the engine combustion process. Parametric studies are conducted by varying the initial mixture temperature, water, and oil content in the fuel. The studies utilize numerical simulations conducted with detailed chemistry for natural gas with n-heptane used as a surrogate for oil. Water addition to natural gas at 1–5% by volume did not result in any major changes in the combustion processes, other than a slight reduction in laminar flame speeds. Oil addition of 1–5% by volume reduced autoignition temperature by 5–10% and ignition delay by 27–95% depending on the initial temperature. Sensitivity analysis showed that this was likely due to decrease in the sensitivity of two recombination reactions with oil addition. Evolution profiles of key radical species also showed increasing mole fraction of the hydroperoxy radical at lower temperature that likely aids in reducing the ignition delay. Oil addition resulted in a relatively small increase in the laminar flame speed of 1.7% along with an increase in the adiabatic flame temperature. These results help inform the combustion process and performance to be expected from the bimodal engine.

Laminar Flame Speed Measurements and Modeling of Alkane Blends at Elevated Pressures With Various Diluents

2011 ◽  
Author(s):  
Yash Kochar ◽  
Jerry Seitzman ◽  
Timothy Lieuwen ◽  
Wayne Metcalfe ◽  
Sine´ad Burke ◽  
...  
Keyword(s):  
Chemical Kinetics ◽  
Laminar Flame ◽  
Initial Pressure ◽  
Elevated Pressure ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Fuel Blends ◽  
Elevated Pressures ◽  
Flame Method ◽  
The Stability

Laminar flame speeds at elevated pressure for methane-based fuel blends are important for refining the chemical kinetics that are relevant at engine conditions. The present paper builds on earlier measurements and modeling by the authors by extending the validity of a chemical kinetics mechanism to laminar flame speed measurements obtained in mixtures containing significant levels of helium. Such mixtures increase the stability of the experimental flames at elevated pressures and extend the range of laminar flame speeds. Two experimental techniques were utilized, namely a Bunsen burner method and an expanding spherical flame method. Pressures up to 10 atm were studied, and the mixtures ranged from pure methane to binary blends of CH4/C2H6 and CH4/C3H8. In the Bunsen flames, the data include elevated initial temperatures up to 650 K. There is generally good agreement between model and experiment, although some discrepancies still exist with respect to equivalence ratio for certain cases. A significant result of the present study is that the effect of mixture composition on flame speed is well captured by the mechanism over the extreme ranges of initial pressure and temperature covered herein. Similarly, the mechanism does an excellent job at modeling the effect of initial temperature for methane-based mixtures up to at least 650 K.

Estimating Laminar Flame Speed and Ignition Delay for a Series of Natural Gas Mixtures at IC Engine-Relevant Conditions

2019 ◽  
Vol 142 (6) ◽  
Author(s):  
Kelsey Fieseler ◽  
Taylor Linker ◽  
Mark Patterson ◽  
Daniel Rem ◽  
Timothy J. Jacobs
Keyword(s):  
Natural Gas ◽  
Ignition Delay ◽  
Laminar Flame ◽  
Initial Conditions ◽  
Initial Pressure ◽  
Fuel Mixture ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Ic Engine ◽  
The Impact

Abstract Two equations are developed to estimate laminar flame speed and ignition delay for different alkane mixtures at a range of engine-relevant conditions. Fuel mixtures of methane, ethane, propane, butane, and pentane were selected by analyzing the natural gas composition in a natural gas pipeline located in the Midwestern United States. The laminar flame speed and ignition delay were calculated for each mixture at each set of conditions using Cantera, a chemical kinetics solver. The range of initial conditions for laminar flame speed includes temperatures from 300 to 700 K, pressures from 1 to 40 bar, equivalence ratios from 0.4 to 1.2, and residual fractions from 0% to 20%. These data were then fit to a non-linear regression. The range of initial conditions for the ignition delay equation includes temperatures from 1100 to 2000 K, pressures from 1 to 40 bar, equivalence ratios from 0.4 to 1.15, and residual fractions from 0% to 20%. These data were fit to a previously developed equation. Sensitivity studies were conducted on each equation to quantify the impact of the independent variables on the target variable. This showed that, for laminar flame speed, the initial pressure, temperature, and equivalence ratio had the largest impact, with fuel composition having a lesser impact. For ignition delay, the temperature and pressure were shown to have the largest impact. There is a room for improvement, namely, increasing the fuel mixture variability and range of initial conditions, and developing a better fit to the data.

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

2009 ◽  
Vol 132 (2) ◽  
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 K 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 at rich conditions.

The Influence of Singlet Oxygen and Ozone on the Combustion in Methane-Air Mixture

2013 ◽  
Vol 699 ◽  
pp. 111-118
Author(s):  
Rui Shi ◽  
Chang Hui Wang ◽  
Yan Nan Chang
Keyword(s):  
Singlet Oxygen ◽  
Chemical Kinetics ◽  
Mole Fraction ◽  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Laminar Flame ◽  
Combustion Products ◽  
Flame Speed ◽  
Air Mixing

Based on GRI3.0, we study the main chemical kinetics process about reactions of singlet oxygen O2(a1Δg) and ozone O3 with methane-air combustion products, inherit and further develop research in chemical kinetics process with enhancement effects on methane-air mixed combustion by these two molecules. In addition, influence of these two molecules on ignition delay time and flame speed of laminar mixture are considered in our numerical simulation research. This study validates the calculation of this model which cotains these two active molecules by using experimental data of ignition delay time and the speed of laminar flame propagation. In CH4-air mixing laminar combustion under fuel-lean condition(ф=0.5), flame speed will be increased, and singlet oxygen with 10% of mole fraction increases it by 80.34%, while ozone with 10% mole fraction increase it by 127.96%. It mainly because active atoms and groups(O, H, OH, CH3, CH2O, CH3O, etc) will be increased a lot after adding active molecules in the initial stage, and chain reaction be reacted greatly, inducing shortening of reaction time and accelerating of flame speed. Under fuel rich(ф=1.5), accelerating of flame speed will be weakened slightly, singlet oxygen with 10% in molecular oxygen increase it by 48.93%, while ozone with 10% increase it by 70.25%.

Sign in / Sign up

Export Citation Format

Share Document