Laminar Flame Velocity of Syngas Fuels

2010 ◽  
Author(s):  
Bidhan Dam ◽  
Vishwanath Ardha ◽  
Ahsan Choudhuri
Keyword(s):  
Laminar Flame ◽  
Burning Velocity ◽  
Flame Velocity ◽  
Laminar Burning Velocity ◽  
Velocity Data ◽  
Flame Propagation Velocity ◽  
Exit Velocity ◽  
Flat Flame ◽  
Burner Exit

The paper presents the experimental measurements of the laminar burning velocity of H2-CO mixtures. Hydrogen (H2) and carbon monoxide (CO) are the two primary constituents of syngas fuels. Three burner systems (nozzle, tubular, and flat flame) are used to quantify the effects of burner exit velocity profiles on the determination of laminar flame propagation velocity. The effects to N2 and CO2 diluents have been investigated as well, and it is observed that the effects of N2 and CO2 on the mixture burning velocity are significantly different. Finally, the burning velocity data of various syngas compositions (brown, bituminous, lignite and coke) are presented.

A Laminar Burning Velocity Correlation for Hydrogen/Air Mixtures Valid at Spark-Ignition Engine Conditions

2003 ◽  
Author(s):  
Sebastian Verhelst ◽  
Roger Sierens
Keyword(s):  
Chemical Kinetics ◽  
Laminar Flame ◽  
Burning Velocity ◽  
Spark Ignition ◽  
Flame Speed ◽  
Spark Ignition Engine ◽  
Laminar Flame Speed ◽  
Spark Ignition Engines ◽  
Laminar Burning Velocity ◽  
Velocity Correlation

During the development of a quasi-dimensional simulation programme for the combustion of hydrogen in spark-ignition engines, the lack of a suitable laminar flame speed formula for hydrogen/air mixtures became apparent. A literature survey shows that none of the existing correlations covers the entire temperature, pressure and mixture composition range as encountered in spark-ignition engines. Moreover, there is ambiguity concerning the pressure dependence of the laminar burning velocity of hydrogen/air mixtures. Finally, no data exists on the influence of residual gases. This paper looks at several reaction mechanisms found in the literature for the kinetics of hydrogen/oxygen mixtures, after which one is selected that corresponds best with available experimental data. An extensive set of simulations with a one-dimensional chemical kinetics code is performed to calculate the laminar flame speed of hydrogen/air mixtures, in a wide range of mixture compositions and initial pressures and temperatures. The use of a chemical kinetics code permits the calculation of any desired set of conditions and enables the estimation of interactions, e.g. between pressure and temperature effects. Finally, a laminar burning velocity correlation is presented, valid for air-to-fuel equivalence ratios λ between 1 and 3 (fuel-to-air equivalence ratio 0.33 < φ < 1), initial pressures between 1 bar and 16 bar, initial temperatures between 300 K and 800 K and residual gas fractions up to 30 vol%. These conditions are sufficient to cover the entire operating range of hydrogen fuelled spark-ignition engines.

scholarly journals EXPERIMENTAL DETERMINATION OF LAMINAR BURNING VELOCITY OF BIOGAS AT PRESSURES UP TO 5 BAR

2018 ◽  
Vol 17 (2) ◽  
pp. 03
Author(s):  
L. Pizzuti ◽  
C. A. Martins ◽  
L. R. Santos
Keyword(s):  
Equivalence Ratio ◽  
Burning Velocity ◽  
Initial Pressure ◽  
Experimental Setup ◽  
Laminar Burning Velocity ◽  
Gaseous Mixtures ◽  
Experimental Procedure ◽  
Constant Volume Combustion Chamber ◽  
Percentage Standard Deviation

This paper presents a very detailed description of a new cylindrical constant volume combustion chamber designed for laminar burning velocity determination of gaseous mixtures at ambient temperature and initial pressure up to 6 bar. The experimental setup, the experimental procedure and the determination of the range of flame radius for laminar burning determination are all described in details. The laminar burning velocity of twelve synthetic biogas mixtures has been studied. Initial pressure varying between 1 and 5 bar, equivalence ratios, f, between 0.7 and 1.1 and percentage dilution, with a mixture of CO2 and N2, between 35 and 55% have been considered. Five experiments were run for each mixture providing a maximum percentage standard deviation of 8.11%. However, for two third of the mixtures this value is lower than 3.55%. A comparison with simulation using PREMIX for both GRI-Mech 3.0 and San Diego mechanisms has provided closer agreement for mixtures with equivalence ratio closer to stoichiometry whereas for f = 0.7 the deviation is larger than 15% for all pressures. Mixtures with lower equivalence ratio, higher dilution percentage and higher initial pressure presents the lower values of laminar burning velocity.

The determination of burning velocities of slow flames

1955 ◽  
Vol 228 (1174) ◽  
pp. 297-322 ◽  
Keyword(s):  
Carbon Monoxide ◽  
Burning Velocity ◽  
Flame Temperature ◽  
Excess Energy ◽  
Flat Flame ◽  
Straight Line ◽  
Flame Burner ◽  
Line Relationship ◽  
Propane Butane

Measurements of the burning velocities of methane, ethane, propane, butane, ethylene, carbon monoxide and cyanogen mixtures with air, in the range about 4 to 8 cm, are made by the flat-flame burner method with an accuracy of 2 to 3%. The results can be represented by a straight-line relationship between composition and burning velocity except for carbon monoxide which is sensitive to the percentage of water vapour present. Extrapolated values agree well with recent measurements of faster flames. Measurements are also made on binary mixtures with air of the gases, including hydrogen. The mixture law holds except with mixtures containing carbon monoxide. Limits of inflammability are also determined and the burning velocities at the limits average 3⋅6 cm/s. The mixtures obey the Le Chatelier rule accurately, except for carbon monoxide mixtures. The burning velocities of the hydrocarbons can be represented approximately by a straight-line relationship with the heat generated and with the maximum flame temperature, but correlation is best when thermal conductivity is introduced. At a given velocity the excess energy maintained by the flame appears to be constant for all the hydrocarbons investigated, except methane, which behaves slightly differently. The burning velocities of the hydrocarbons are controlled by a reaction which provides reasonable values of the activation energies and probably precedes the sudden development of chain branching.

Inhibition of Premixed Methane-Air Flames with CF3I

2009 ◽  
Vol 4 (3) ◽  
Author(s):  
Caimao Luo ◽  
Bogdan Dlugogorski ◽  
Eric Kennedy ◽  
Behdad Moghtaderi
Keyword(s):  
Sensitivity Analysis ◽  
Pathway Analysis ◽  
Laminar Flame ◽  
Computational Study ◽  
Reaction Pathway ◽  
Burning Velocity ◽  
Flame Velocity ◽  
Promoting Effect ◽  
Elementary Reactions ◽  
Reaction Pathway Analysis

This paper presents a systematic computational study of the inhibition of premixed flames of short chain hydrocarbons with CF3I, focusing on sensitivity analysis of the (normalized) burning velocity and reaction pathway analysis using the "iodine-flux" approach. A comprehensive kinetic mechanism was obtained by combining the GRI, hydrofluorocarbon and CF3I sub-mechanisms, and updating the rates of some of the elementary reactions. Calculations were performed using the PREMIX computer code in the CHEMKIN suite of computer codes. The updated mechanism yielded estimates of the normalized laminar burning velocities which concurs closely with published measurements. The sensitivity analysis resulted in a positive coefficient for CF3I + M ? CF3 + I + M, confirming the promoting effect of CF3I on the laminar flame velocity and is consistent with previous studies. Reaction pathways were drawn for stoichiometric, fuel-lean and fuel-rich flames doped with 1 and 2% of CF3I at atmospheric pressure. The reaction pathway analysis served to identify four major inhibition cycles, denoted as HI ? I ? HI, HI ? I ? I2 ? HI, HI ? I ? CH3I ? HI and HI ? I ? C2H5I ? HI. Furthermore, the paper developed a linear expression linking the normalized rate of heat release with the ratio of laminar burning velocities of mitigated and non-mitigated flames, and verified the efficacy of this expression for flames inhibited with CF3I.

Laminar Flame Velocity of Components of Natural Gas

2011 ◽  
Author(s):  
P. Dirrenberger ◽  
P. A. Glaude ◽  
H. Le Gall ◽  
R. Bounaceur ◽  
O. Herbinet ◽  
...  
Keyword(s):  
Heat Flux ◽  
Natural Gas ◽  
Gas Turbines ◽  
Laminar Flame ◽  
Flame Stabilization ◽  
Flame Velocity ◽  
Flux Method ◽  
Radial Temperature ◽  
Flat Flame ◽  
Wide Range

Laminar burning velocities are important parameters in many areas of combustion science such as the design of burners or engines and for the prediction of explosions. They play an essential role in the combustion in gas turbines for the optimization of the nozzles and of the combustion chamber. Adiabatic laminar flame velocities are usually investigated in three types of apparatus which are currently available for that type of measurements: constant volume bombs in which the propagation of a flame is initiated by two electrodes and followed by shadowgraphy, counterflow-flame burners with axial velocity profiles determined by Particle Imaging Velocimetry, and flat flame adiabatic burners which consist of a heated burner head mounted on a plenum chamber with the radial temperature distribution measurement made by a series of thermocouples (used in this work). This last method is based on a balance between the heat loss from the flame to the burner required for the flame stabilization and the convective heat flux from the burner surface to the flame front. It was demonstrated that this heat flux method is suitable for the determination of the adiabatic flame temperature and flame burning velocity. The main hydrocarbon in natural gas is methane, with smaller amounts of heavier compounds, mainly species from C2 to C4. New experimental measurements have been performed by the heat flux method using a newly built flat flame adiabatic burner at atmospheric pressure. These measurements of laminar flame speeds are presented for components of natural gas, methane, ethane, propane and n-butane, as well as for binary and tertiary mixtures of these compounds representative of different natural gases available in the world. Results for pure alkanes were compared successfully to the literature. The composition of the investigated air/hydrocarbon mixtures covers a wide range of equivalence ratios, from 0.6 to 2.1 when it is possible to sufficiently stabilize the flame. Empirical correlations have been derived in order to predict accurately the flame velocity of a natural gas containing C1 up to C4 alkanes as a function of its composition and the equivalence ratio.

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