CO and H2O Time-Histories in Shock-Heated Blends of Methane and Ethane for Assessment of a Chemical Kinetics Model

2017 ◽  
Author(s):  
O. Mathieu ◽  
C. Mulvihill ◽  
E. L. Petersen ◽  
Y. Zhang ◽  
H. J. Curran
Keyword(s):  
Gas Turbine ◽  
Chemical Kinetics ◽  
Laminar Flame ◽  
Combustion Process ◽  
Practical Interest ◽  
Time History ◽  
Good Marker ◽  
Ignition Delay Times ◽  
Time Histories ◽  
Detailed Kinetics

Methane and ethane are the two main components of natural gas and typically constitute more than 95% of it. In this study, a mixture of 90% CH4 /10% C2H6 diluted in 99% Ar was studied at fuel lean (ϕ = 0.5) conditions, for pressures around 1, 4, and 10 atm. Using laser absorption diagnostics, the time histories of CO and H2O were recorded between 1400 and 1800 K. Water is a final product from hydrocarbon combustion, and following its formation is a good marker of the completion of the combustion process. Carbon monoxide is an intermediate combustion species, a good marker of incomplete/inefficient combustion, as well as a regulated pollutant for the gas turbine industry. Measurements such as these species time histories are important for validating and assessing chemical kinetics models beyond just ignition delay times and laminar flame speeds. Time-history profiles for these two molecules measured herein were compared to a modern, state-of-the-art detailed kinetics mechanism as well as to the well-established GRI 3.0 mechanism. Results show that the H2O profile is accurately reproduced by both models. However, discrepancies are observed for the CO profiles. Under the conditions of this study, the measured CO profiles typically increase rapidly after an induction time, reach a maximum and then decrease. This maximum CO mole fraction is often largely over-predicted by the models, whereas the depletion rate of CO past this peak is often over-estimated by the models for pressures above 1 atm. This study demonstrates the need to improve on the accuracy of the HCCO reactions involved in CO formation for pressures of practical interest for the gas turbine industry.

CO and H2O Time-Histories in Shock-Heated Blends of Methane and Ethane for Assessment of a Chemical Kinetics Model

2017 ◽  
Vol 139 (12) ◽  
Author(s):  
O. Mathieu ◽  
C. R. Mulvihill ◽  
E. L. Petersen ◽  
Y. Zhang ◽  
H. J. Curran
Keyword(s):  
Chemical Kinetics ◽  
Laminar Flame ◽  
Combustion Process ◽  
Time History ◽  
Good Marker ◽  
Ignition Delay Times ◽  
Depletion Rate ◽  
Time Histories ◽  
Main Components ◽  
Detailed Kinetics

Methane and ethane are the two main components of natural gas and typically constitute more than 95% of it. In this study, a mixture of 90% CH4/10% C2H6 diluted in 99% Ar was studied at fuel lean (equiv. ratio = 0.5) conditions, for pressures around 1, 4, and 10 atm. Using laser absorption diagnostics, the time histories of CO and H2O were recorded between 1400 and 1800 K. Water is a final product from combustion, and its formation is a good marker of the completion of the combustion process. Carbon monoxide is an intermediate combustion species, a good marker of incomplete/inefficient combustion, as well as a regulated pollutant for the gas turbine industry. Measurements such as these species time histories are important for validating and assessing chemical kinetics models beyond just ignition delay times and laminar flame speeds. Time-history profiles for these two molecules were compared to a state-of-the-art detailed kinetics mechanism as well as to the well-established GRI 3.0 mechanism. Results show that the H2O profile is accurately reproduced by both models. However, discrepancies are observed for the CO profiles. Under the conditions of this study, the CO profiles typically increase rapidly after an induction time, reach a maximum, and then decrease. This maximum CO mole fraction is often largely over-predicted by the models, whereas the depletion rate of CO past this peak is often over-estimated for pressures above 1 atm.

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 Evaluation of Reduced Kinetics in Simulation of Gasified Biomass Gas Combustion

2013 ◽  
Author(s):  
Xiaoxiang Zhang ◽  
Nur Farizan Munjat ◽  
Jeevan Jayasuriya ◽  
Reza Fakhrai ◽  
Torsten Fransson
Keyword(s):  
Gas Turbine ◽  
Chemical Kinetics ◽  
Cfd Simulation ◽  
Laminar Flame ◽  
Turbulent Flame ◽  
Flame Speed ◽  
Turbulent Flame Speed ◽  
Operation Conditions ◽  
Simulation Results ◽  
Gas Turbine Combustion

It is essentially important to use appropriate chemical kinetic models in the simulation process of gas turbine combustion. To integrate the detailed kinetics into complex combustion simulations has proven to be a computationally expensive task with tens to thousands of elementary reaction steps. It has been suggested that an appropriate simplified kinetics which are computationally efficient could be used instead. Therefore reduced kinetics are often used in CFD simulation of gas turbine combustion. At the same time, simplified kinetics for specific fuels and operation conditions need to be carefully selected to fulfill the accuracy requirements. The applicability of several simplified kinetics for premixed Gasified Biomass Gas (GBG) and air combustion are evaluated in this paper. The current work is motivated by the growing demand of gasified biomass gas (GBG) fueled combustion. Even though simplified kinetic schemes developed for hydrocarbon combustions are published by various researchers, there is little research has been found in literature to evaluate the ability of the simplified chemical kinetics for the GBG combustion. The numerical Simulation tool “CANTERA” is used in the current study for the comparison of both detailed and simplified chemical kinetics. A simulated gas mixture of CO/H2/CH4/CO2/N2 is used for the current evaluation, since the fluctuation of GBG components may have an unpredictable influence on the simulation results. The laminar flame speed has an important influence with flame stability, extinction limits and turbulent flame speed, here it is chosen as an indicator for validation. The simulation results are compared with the experimental data from the previous study [1] which is done by our colleagues. Water vapour which has shown a dilution effect in the experimental study are also put into concern for further validation. As the results indicate, the reduced kinetics which are developed for hydrocarbon or hydrogen combustion need to be highly optimized before using them for GBG combustion. Further optimization of the reduced kinetics is done for GBG and moderate results are achieved using the optimized kinetics compared with the detailed combustion kinetics.

Biogas Combustion and Chemical Kinetics for Gas Turbine Applications

2008 ◽  
Author(s):  
Saeed Jahangirian ◽  
Abraham Engeda
Keyword(s):  
Gas Turbine ◽  
Chemical Kinetics ◽  
Laminar Flame ◽  
Biogas Production ◽  
Agricultural Waste ◽  
Detailed Chemical Kinetics ◽  
Fuel Blends ◽  
Reduced Mechanism ◽  
Turbine Design ◽  
Detailed Chemical

Biogas is produced from anaerobic digestion of biodegradable materials such as agricultural waste, animal waste, and municipal solid waste and its main constituents are CH4 and CO2. A review of biogas production and benefits as well as its combustion as an alternative gas turbine fuel is presented. To further understand the characteristics of biogas combustion, a detailed chemical kinetics study of biogas is conducted using the GRI-Mech 3.0 and the San Diego detailed mechanisms and a reduced mechanism in a counterflow configuration. Ignition delays and laminar flame speeds of some gaseous fuel blends which simulate biogas are calculated. Effects of the concentration of each species in the blend are discussed as well as its chemical contribution in the biogas combustion. Approximate analytical correlations are extracted from these results for quantitative predictions. Results of this study will provide valuable data both for gas turbine manufacturers and for biogas producers to modify the gas turbine design for biogas and to figure out how much cleaning and upgrading is required for biogas turbines.

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.

Ignition delay times, laminar flame speeds, and species time-histories in the H2S/CH4 system at atmospheric pressure

2019 ◽  
Vol 37 (1) ◽  
pp. 735-742 ◽  
Author(s):  
Clayton R. Mulvihill ◽  
Charles L. Keesee ◽  
Travis Sikes ◽  
Rodolfo S. Teixeira ◽  
Olivier Mathieu ◽  
...  
Keyword(s):  
Ignition Delay ◽  
Atmospheric Pressure ◽  
Laminar Flame ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Time Histories

Numerical Investigation of Combustion Instability in a V-Gutter Stabilized Combustor

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
S. Soma Sundaram ◽  
V. Babu
Keyword(s):  
Heat Release ◽  
Combustion Process ◽  
Symmetry Plane ◽  
Time History ◽  
Dominant Mode ◽  
Mode Shapes ◽  
Computational Domain ◽  
Frequency Spectra ◽  
Time Histories ◽  
Rayleigh Index

The stability of the combustion process in a V-gutter stabilized combustor is numerically investigated. To this end, 3D compressible turbulent and unsteady reacting flow calculations have been carried out using LES. The time history of the pressure at several locations is used to determine the frequency and amplitude of the oscillations along with the mode shapes. A shift in the dominant mode of the frequency spectra from the acoustic mode to the hydrodynamic mode is observed. A POD analysis of pressure time histories on the symmetry plane also corroborates this trend. The computational domain is divided into several subvolumes in the wake region of the V-gutter and the time histories of pressure, temperature, and heat release are collected in the individual volumes. It is seen that the fluctuation of pressure and heat release tend to oscillate from being in phase to out of phase over a time period. Unstable regions predicted by the Rayleigh index across a plane are shown to be different from those predicted in a volume owing to the three dimensionality of the flame. Quite interestingly, the calculated values of the indices show the combustor to be most unstable for an equivalence ratio of 0.1665 which is not the leanest one considered here. The global Rayleigh index is shown to correlate well with the amplitude of the dominant mode.

Syngas Laminar Flame Speed Computation and its Application to Gaseous Fueled Spark Ignited Engines Performance Prediction

2016 ◽  
Author(s):  
Hui Xu ◽  
Leon A. LaPointe ◽  
Robin J. Bremmer
Keyword(s):  
Natural Gas ◽  
Chemical Kinetics ◽  
Laminar Flame ◽  
Combustion Process ◽  
Engine Performance ◽  
Ambient Conditions ◽  
Piston Engine ◽  
Natural Gas Engines ◽  
Gaseous Fuels ◽  
Engine Combustion

Gaseous fueled spark ignited (SI) engines are often developed using pipeline quality natural gas as the fuel. However, natural gas engines are occasionally expected by customers to accommodate different fuel compositions when deployed in the field. Depending on the source or production processing of the fuel and the ambient conditions, gaseous fuels can have different levels of heavy hydrocarbons and/or significant levels of diluents when compared to natural gas. In recent years, there are increasing interests in using synthesis gas (syngas) from renewable sources in gaseous fueled spark ignition engines. This work investigated syngas compositions from different production processes and describes a methodology to predict engine performance using syngas. Syngas composition variations can provide different laminar flame speeds (LFS), which can result in changes in combustion burn rate, heat release rate and knock likelihood, if the engine combustion process is not optimized appropriately. It is challenging to obtain LFS data at the high pressure and temperature conditions that are characteristic of the piston engine combustion process. It has proven to be effective to employ a chemical kinetics solver using an appropriate chemical kinetics mechanism to obtain LFS values under piston engine combustion conditions. Alternative chemical kinetics mechanisms were investigated to identify one which best characterized combustion performance relative to detailed rig and engine measurements. With this appropriate chemical kinetics mechanism, LFS results are now used to guide natural gas engine combustion tuning when using syngas as a fuel. Engine performance is predicted in terms of NOx emissions and knock likelihood using the in-house developed methodology.

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.

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