A model for the laminar flame speed of binary fuel blends and its application to methane/hydrogen mixtures

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.

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Flashback Limits of Premixed H2/CH4 Flames in a Swirl-Stabilized Combustor

Volume 2: Combustion, Fuels and Emissions, Parts A and B ◽

10.1115/gt2010-23623 ◽

2010 ◽

Cited By ~ 1

Author(s):

Nasser Shelil ◽

Anthony Griffiths ◽

Audrius Bagdanavicius ◽

Nick Syred

Keyword(s):

Atmospheric Pressure ◽

Laminar Flame ◽

Flame Speed ◽

Cfd Modeling ◽

Pure Hydrogen ◽

Laminar Flame Speed ◽

Operating Pressure ◽

Mixture Ratio ◽

Fuel Blends ◽

Pure Methane

CFD modeling is used to simulate the combustion and flashback behavior of H2/CH4 fuel blends with air in a premixed swirl burner using a three dimensional–finite volume model. Preliminary work was performed to calculate the laminar flame speed for H2/CH4 blends from pure methane up to pure hydrogen at various pressures, temperatures and equivalence ratios by using CHEMKIN, for pure fuels, and a new approximation based on the gravimetric mixture ratio, for the fuel blends. Then, the numerical values for laminar flame speed were fed to a FLUENT CFD model to create a PDF table for turbulent premixed combustion calculations and flashback studies. Flashback limits were defined and determined for H2/CH4 blends ranging from 0% (pure methane) up to 100% (pure hydrogen) based on the volumetric composition at atmospheric pressure and 300K for various equivalence ratios. The simulations were compared with experimental measurements at atmospheric pressure for two fuel blends with γ of 0.15 and 0.3 and showed best fit for equivalence ratios less than 0.75 to 0.8. The work was then extended to include simulation studies to investigate the effect of operating pressure and raw gases temperature on flame stability and showed a high dependence on both operating pressure and raw gases temperature.

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

Volume 2: Combustion, Fuels and Emissions, Parts A and B ◽

10.1115/gt2011-45122 ◽

2011 ◽

Cited By ~ 17

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.

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Comparison of Laminar Flame Speeds, Extinction Stretch Rates and Vapor Pressures of Jet A-1/HRJ Biojet Fuel Blends

Volume 3A: Coal, Biomass and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration ◽

10.1115/gt2014-25951 ◽

2014 ◽

Cited By ~ 3

Author(s):

Jeffrey D. Munzar ◽

Ahmed Zia ◽

Philippe Versailles ◽

Rodrigo Jiménez ◽

Jeffrey M. Bergthorson ◽

...

Keyword(s):

Vapor Pressure ◽

Laminar Flame ◽

Alternative Fuel ◽

Jet Fuel ◽

Flame Speed ◽

Aviation Industry ◽

Laminar Flame Speed ◽

Vapor Pressures ◽

Fuel Blends ◽

Combustion Properties

An emerging goal within the aviation industry is to replace conventional jet fuel with biologically-derived alternative fuel sources. However, the combustion properties of these potential fuels must be thoroughly characterized before they can be considered as replacements in turbomachinery applications. In this study, seven candidate alternative fuel blends, derived from two biological feedstocks and blended in different quantities with Jet A-1, are considered. For each blend, the laminar flame speed, non-premixed extinction stretch rate, and vapor pressure are experimentally determined and compared to numerical simulations and to Jet A-1 data. Hydrodynamically-stretched flame speeds are determined by applying particle image velocimetry (PIV) to an atmospheric pressure, preheated jet-wall stagnation flame, and the unstretched laminar flame speed is inferred using a direct comparison method in conjunction with a binary jet-fuel surrogate, with results spanning a wide equivalence ratio range. Extinction stretch rates were measured using particle tracking velocimetry (PTV) in a non-premixed counterflow diffusion flame, over a range of fuel mass fractions diluted in nitrogen carrier gas. Finally, the vapor pressure of the seven biojet/Jet A-1 fuel blends was measured using an isoteniscope over a wide temperature range. The results of this study indicate that moderate blends of hydrotreated renewable jet (HRJ) fuel with Jet A-1 have similar combustion properties to conventional jet fuel, highlighting their suitability as drop-in replacements, while higher blend levels of HRJ fuel, regardless of the crop source, lead to definitive changes in the combustion parameters investigated here.

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Dual Fuel Reaction Mechanism 2.0 including NOx Formation and Laminar Flame Speed Calculations Using Methane/Propane/n-Heptane Fuel Blends

Energies ◽

10.3390/en13040778 ◽

2020 ◽

Vol 13 (4) ◽

pp. 778

Author(s):

Sebastian Schuh ◽

Franz Winter

Keyword(s):

San Diego ◽

Laminar Flame ◽

Flame Speed ◽

Rate Coefficients ◽

Dual Fuel ◽

Laminar Flame Speed ◽

Nox Formation ◽

Fuel Blends ◽

Start Of Injection ◽

Ignition And Combustion

This study presents the further development of the TU Wien dual fuel mechanism, which was optimized for simulating ignition and combustion in a rapid compression expansion machine (RCEM) in dual fuel mode using diesel and natural gas at pressures higher than 60 bar at the start of injection. The mechanism is based on the Complete San Diego mechanism with n-heptane extension and was attuned to the RCEM measurements to achieve high agreement between experiments and simulation. This resulted in a specific application area. To obtain a mechanism for a wider parameter range, the Arrhenius parameter changes performed were analyzed and updated. Furthermore, the San Diego nitrogen sub-mechanism was added to consider NOx formation. The ignition delay time-reducing effect of propane addition to methane was closely examined and improved. To investigate the propagation of the flame front, the laminar flame speed of methane–air mixtures was simulated and compared with measured values from literature. Deviations at stoichiometric and fuel-rich conditions were found and by further mechanism optimization reduced significantly. To be able to justify the parameter changes performed, the resulting reaction rate coefficients were compared with data from the National Institute of Standards and Technology chemical kinetics database.

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Effect of methane-dimethyl ether fuel blends on flame stability, laminar flame speed, and Markstein length

Proceedings of the Combustion Institute ◽

10.1016/j.proci.2010.05.042 ◽

2011 ◽

Vol 33 (1) ◽

pp. 929-937 ◽

Cited By ~ 32

Author(s):

W.B. Lowry ◽

Z. Serinyel ◽

M.C. Krejci ◽

H.J. Curran ◽

G. Bourque ◽

...

Keyword(s):

Dimethyl Ether ◽

Laminar Flame ◽

Flame Speed ◽

Flame Stability ◽

Laminar Flame Speed ◽

Markstein Length ◽

Fuel Blends

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Effect of Steam Dilution on Laminar Flame Speeds of Syngas Fuel Blends at Elevated Pressures and Temperatures

Volume 3: Coal, Biomass, Hydrogen, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems ◽

10.1115/gt2019-90570 ◽

2019 ◽

Author(s):

Michael C. Krejci ◽

Charles L. Keesee ◽

Andrew J. Vissotski ◽

Sankaranarayanan Ravi ◽

Eric L. Petersen

Keyword(s):

Gas Turbine ◽

Laminar Flame ◽

Flame Structure ◽

Industrial Process ◽

Flame Speed ◽

Laminar Flame Speed ◽

Limited Information ◽

Fuel Blends ◽

Elevated Pressures ◽

Negative Effect

Abstract Synthetic gas, syngas, is a popular alternative fuel for the gas turbine industry. However, the composition of syngas can contain different types and amounts of contaminates, such as carbon dioxide, moisture, and nitrogen, depending on the industrial process involved in its manufacturing. The presence of steam in syngas blends is of particular interest from a thermo-chemical perspective as there is limited information available in the literature. This study investigated the effect of moisture content (0–15% by volume), temperature (323–423 K), and pressure (1–10 atm) on syngas mixtures by measuring the laminar flame speed in a constant-volume, heated experimental facility. A design-of-experiments methodology was applied to these variables to efficiently cover the widest range of conditions that are relevant to the gas turbine industry. The experimental flame speed data were compared to a recent chemical kinetics model showing good agreement. Also, the measured Markstein lengths of atmospheric mixtures were compared and demonstrate that temperature and steam dilution have weak impacts on the sensitivity to stretch in comparison with an increase of carbon monoxide concentration. Mixtures with high levels of CO stabilize the flame structure of thermal-diffusive instability. The increase of steam dilution has only a small effect on the laminar flame speed of high-CO mixtures, while more hydrogen-dominated mixtures demonstrate a much larger and negative effect of increasing water content on the laminar flame speed.

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A Numerical Study on the Reactivity of Biogas/Reformed-Gas/Air and Methane/Reformed-Gas/Air Mixtures at Gas Turbine Relevant Conditions

Volume 3: Coal, Biomass and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems ◽

10.1115/gt2016-56655 ◽

2016 ◽

Cited By ~ 3

Author(s):

Pablo Diaz Gomez Maqueo ◽

Philippe Versailles ◽

Gilles Bourque ◽

Jeffrey M. Bergthorson

Keyword(s):

Gas Turbine ◽

Laminar Flame ◽

Numerical Study ◽

Flame Temperature ◽

Flame Speed ◽

Flame Stability ◽

Laminar Flame Speed ◽

Fuel Reforming ◽

Numerical Work ◽

Chemical Effects

This study investigates the increase in methane and biogas flame reactivity enabled by the addition of syngas produced through fuel reforming. To isolate thermodynamic and chemical effects on the reactivity of the mixture, the burner simulations are performed with a constant adiabatic flame temperature of 1800 K. Compositions and temperatures are calculated with the chemical equilibrium solver of CANTERA® and the reactivity of the mixture is quantified using the adiabatic, freely-propagating premixed flame, and perfectly-stirred reactors of the CHEMKIN-Pro® software package. The results show that the produced syngas has a content of up to 30 % H2 with a temperature up to 950 K. When added to the fuel, it increases the laminar flame speed while maintaining a burning temperature of 1800 K. Even when cooled to 300 K, the laminar flame speed increases up to 30 % from the baseline of pure biogas. Hence, a system can be developed that controls and improves biogas flame stability under low reactivity conditions by varying the fraction of added syngas to the mixture. This motivates future experimental work on reforming technologies coupled with gas turbine exhausts to validate this numerical work.

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