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

2014 ◽  
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.

Flame Speed and Vapor Pressure of Biojet Fuel Blends

2013 ◽  
Author(s):  
Jeffrey D. Munzar ◽  
Bradley M. Denman ◽  
Rodrigo Jiménez ◽  
Ahmed Zia ◽  
Jeffrey M. Bergthorson
Keyword(s):  
Vapor Pressure ◽  
Alternative Fuels ◽  
Laminar Flame ◽  
Flame Speed ◽  
Aviation Fuel ◽  
Laminar Flame Speed ◽  
Camelina Oil ◽  
Combustion Properties ◽  
Initial Comparison ◽  
Fuel Mixtures

An understanding of the fundamental combustion properties of alternative fuels is essential for their adoption as replacements for non-renewable sources. In this study, three different biojet fuel mixtures are directly compared to conventional Jet A-1 on the basis of laminar flame speed and vapor pressure. The biofuel is derived from camelina oil and hydrotreated to ensure consistent elemental composition with conventional aviation fuel, yielding a bioderived synthetic paraffinic kerosene (Bio-SPK). Two considered blends are biofuel and Jet A-1 mixtures, while the third is a 90% Bio-SPK mixture with 10% aromatic additives. Premixed flame speed measurements are conducted at an unburned temperature of 400K and atmospheric pressure using a jet-wall stagnation flame apparatus. Since the laminar flame speed cannot be studied experimentally, a strained (or reference) flame speed is used as the basis for the initial comparison. Only by using an appropriate surrogate fuel were the reference flame speed measurements extrapolated to zero flame strain, accomplished using a direct comparison of simulations to experiments. This method has been previously shown to yield results consistent with non-linear extrapolations. Vapor pressure measurements of the biojet blends are also made from 25 to 200°C using an isoteniscope. Finally, the biojet blends are compared to the Jet A-1 benchmark on the basis of laminar flame speed at different equivalence ratios, as well as on the basis of vapor pressure over a wide temperature range, and the suitability of a binary laminar flame speed surrogate for these biojet fuels is discussed.

An Experimental and Numerical Study of the Laminar Flame Speed of Jet Fuel Surrogate Blends

2012 ◽  
Author(s):  
Bradley M. Denman ◽  
Jeffrey D. Munzar ◽  
Jeffrey M. Bergthorson
Keyword(s):  
Numerical Simulations ◽  
Laminar Flame ◽  
Velocity Profiles ◽  
Jet Fuel ◽  
Flame Speed ◽  
Aviation Fuel ◽  
Laminar Flame Speed ◽  
Measured Velocity ◽  
Combustion Properties ◽  
Fuel Surrogate

Kerosene-type fuels are the most common aviation fuel, and an understanding of their combustion properties is essential for achieving optimized gas turbine operation. Presently, however, there is lack of experimental flame speed data available by which to validate the chemical kinetic mechanisms necessary for effective computational studies. In this study, premixed jet fuel surrogate blends and commercial kerosene are studied using particle image velocimetry in a stagnation flame geometry. Numerical simulations of each experiment are obtained using the CHEMKIN-PRO software package and the JetSurF 2.0 mechanism. The neat hydrocarbon surrogates investigated include n-decane, methylcyclohexane, and toluene, which represent the alkane, cycloalkane, and aromatic components of conventional aviation fuel, respectively. Two blends are studied in this paper. The first is a binary blend formulated to reproduce the laminar flame speed of aviation fuel using a mixing rule based on the laminar flame speed and adiabatic flame temperature of the hydrocarbon components, weighted by their respective mixture mole fractions. The second blend is a tertiary blend formulated to emulate the hydrogen to carbon ratio of the kerosene studied. All of the considered fuels and blends are studied at three equivalence ratios, corresponding to lean, stoichiometric, and rich conditions, and at several stretch rates. The centreline axial velocity profiles from numerical simulations are directly compared to the measured velocity profiles to validate the mechanism at each condition. The difference between the experimental and simulated reference flame speed is used to infer the true unstretched laminar flame speed of the mixture. These results allow the effectiveness of the different blending methodologies to be assessed.

An experimental and reduced modeling study of the laminar flame speed of jet fuel surrogate components

Fuel ◽  
2013 ◽  
Vol 113 ◽  
pp. 586-597 ◽  
Author(s):  
J.D. Munzar ◽  
B. Akih-Kumgeh ◽  
B.M. Denman ◽  
A. Zia ◽  
J.M. Bergthorson
Keyword(s):  
Laminar Flame ◽  
Jet Fuel ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Reduced Modeling ◽  
Fuel Surrogate ◽  
Modeling Study

scholarly journals The Influence of Diluent Gases on Combustion Properties of Natural Gas: A Combined Experimental and Modeling Study

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Sandra Richter ◽  
Jörn Ermel ◽  
Thomas Kick ◽  
Marina Braun-Unkhoff ◽  
Clemens Naumann ◽  
...  
Keyword(s):  
Power Generation ◽  
Natural Gas ◽  
Laminar Flame ◽  
Ambient Pressure ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Diverse Range ◽  
Combustion Properties ◽  
Modeling Study ◽  
A Share

Currently, new concepts for power generation are discussed, as a response to combat global warming due to CO2 emissions stemming from the combustion of fossil fuels. These concepts include new, low-carbon fuels as well as centralized and decentralized solutions. Thus, a more diverse range of fuel supplies will be used, with (biogenic) low-caloric gases such as syngas and coke oven gas (COG) among them. Typical for theses low-caloric gases is the amount of hydrogen, with a share of 50% and even higher. However, hydrogen mixtures have a higher reactivity than natural gas (NG) mixtures, burned mostly in today's gas turbine combustors. Therefore, in the present work, a combined experimental and modeling study of nitrogen-enriched hydrogen–air mixtures, some of them with a share of methane, to be representative for COG, will be discussed focusing on laminar flame speed data as one of the major combustion properties. Measurements were performed in a burner test rig at ambient pressure and at a preheat temperature T0 of 373 K. Flames were stabilized at fuel–air ratios between about φ = 0.5–2.0 depending on the specific fuel–air mixture. This database was used for the validation of four chemical kinetic reaction models, including an in-house one, and by referring to hydrogen-enriched NG mixtures. The measured laminar flame speed data of nitrogen-enriched methane–hydrogen–air mixtures are much smaller than the ones of nitrogen-enriched hydrogen–air mixtures. The grade of agreement between measured and predicted data depends on the type of flames and the type of reaction model as well as of the fuel–air ratio: a good agreement was found in the fuel lean and slightly fuel-rich regime; a large underprediction of the measured data exists at very fuel-rich ratios (φ > 1.4). From the results of the present work, it is obvious that further investigations should focus on highly nitrogen-enriched methane–air mixtures, in particular for very high fuel–air ratio (φ > 1.4). This knowledge will contribute to a more efficient and a more reliable use of low-caloric gases for power generation.

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.

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

2010 ◽  
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.

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.

Phenomenological Analysis of Combustion of Gaseous Fuels to Measure the Energy Quality and the Capacity to Produce Work in Spark Ignition Engines.

2020 ◽  
Author(s):  
Juan Pablo GOMEZ MONTOYA ◽  
Andres Amell
Keyword(s):  
Energy Density ◽  
Compression Ratio ◽  
Laminar Flame ◽  
Flame Temperature ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Adiabatic Flame Temperature ◽  
Gaseous Fuels ◽  
Combustion Properties ◽  
Si Engines

Abstract Combustion at the knocking threshold was tested using fuels with different methane numbers (MN) in a modified SI engine, with high compression ratio (CR) and high turbulence intensity to the combustion process; fuels were tested in a CFR engine to measure MN and critical compression ratio (CCR); in both engines test were performed just into the knocking threshold. Is proposed that MN to gaseous fuels will be considered in similar way than octane number (ON) to liquid fuels to indicate the energy quality and the capacity to produce work. According to the tests biogas has better combustion properties than the others fuels; biogas is the fuel with the highest knocking resistance; biogas is the fuel with the best energy quality measured with the energy density and combustion temperature; biogas has the highest capacity to produce work in SI engines, because its high MN, low energy density, low laminar flame speed and low adiabatic flame temperature. Fuel combustion phenomenological characteristics were compared using CCR versus: output power, generating efficiency, energy density, laminar flame speed and adiabatic flame temperature. It is suggested that the strategies to suppress knocking are the key to improve the performance of SI engines; knocking is the engine limit to power generation in SI engines and quantum thermal efficiency is defined at this condition.

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

Energies ◽  
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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