Laminar Flame Speeds of Synthetic Gas Fuel Mixtures

2005 ◽  
Author(s):  
J. Natarajan ◽  
S. Nandula ◽  
T. Lieuwen ◽  
J. Seitzman
Keyword(s):  
Temperature Dependence ◽  
Reaction Mechanisms ◽  
Laminar Flame ◽  
Measured Temperature ◽  
Preheat Temperature ◽  
Significant Difference ◽  
Synthetic Gas ◽  
Co2 Levels ◽  
Gas Fuel ◽  
Fuel Mixtures

Laminar flame speeds of H2/CO/CO2 mixtures have been measured over a range of fuel compositions, lean equivalence ratios, and reactant preheat temperature (up to 700 K). The measurements are compared to numerical flame speed predictions based on two reaction mechanisms: GRI Mech 3.0 and a H2/CO mechanism. For undiluted and nonpreheated mixtures, the current results agree with previous data and the numerical calculations over most of the range tested. The measured flame speeds increase as the H2 content of the fuel rises and for higher equivalence ratios. The most significant difference between the measurements and models is for high CO content fuel with the H2/CO mechanism, and the high H2 content fuel at the leanest conditions with the GRI mechanism. For CO2 diluted fuels, measured flame speeds decrease as predicted. However, agreement between the measurements and predictions worsens with increasing CO2 dilution. Deviations as large as 40% are observed at lean equivalence ratios and 20% CO2 levels. For reactant preheat temperatures below ∼400K, the measured flame speeds generally match the calculated flame speeds within 10%. At higher preheat temperatures, however, the discrepancy between the measurements and the calculations increases, reaching levels of ∼30% at 700 K. The measured temperature dependence is closer to the predictions from GRI Mech 3.0 than from the H2/CO mechanism.

Laminar Flame Speed Measurements of H2/CO/CO2 Mixtures Up to 15 atm and 600 K Preheat Temperature

2008 ◽  
Author(s):  
J. Natarajan ◽  
Y. Kochar ◽  
T. Lieuwen ◽  
J. Seitzman
Keyword(s):  
Temperature Dependence ◽  
Atmospheric Pressure ◽  
Radiation Effects ◽  
Laminar Flame ◽  
Elevated Pressure ◽  
Flame Speed ◽  
Preheat Temperature ◽  
Numerical Predictions ◽  
Kinetic Mechanisms ◽  
Fuel Mixtures

Laminar flame speeds of lean H2/CO/CO2 (syngas) fuel mixtures have been measured for a range of H2 levels (20–90% of the fuel) at pressures and reactant preheat temperatures relevant to gas turbine combustors (up to 15 atm and 600 K). A conical flame stabilized on a contoured nozzle is used for the flame speed measurement, which is based on the reaction zone area calculated from chemiluminescence imaging of the flame. A O2:He mixture (1:9 by volume) is used as the oxidizer, rather than standard air, in order to suppress the hydrodynamic and thermo-diffusive instabilities that become prominent at elevated pressure conditions for lean H2/CO fuel mixtures. All the measurements are compared with numerical predictions based on two leading kinetic mechanisms: the H2/CO mechanism of Davis et al. and the C1 mechanism of Li et al. The results generally agree with the findings of an earlier study at atmospheric pressure: 1) for low H2 content (<40%) fuels, the model predictions are in good agreement with measurements at both 300 K and 600 K preheat temperature; but 2) the models tend to over predict the temperature dependence of the flame speed for medium (∼40–60%) and high (> 60%) H2 content fuels, especially at very lean conditions. The elevated pressure (∼15 atm) results, however, reveal that the effect is less pronounced than at atmospheric pressure. The exaggerated temperature dependence of the current models may be due to errors in the temperature dependence used for so-called “low temperature” reactions that become more important as the preheat temperature is increased. The radiation effects associated with CO2 addition to the fuel (up to 40%) is found to be less important for medium and high H2 content syngas fuels at elevated pressure and preheat temperature.

Reduced Reaction Mechanisms for Methane and Syngas Combustion in Gas Turbines

2005 ◽  
Author(s):  
N. Slavinskaya ◽  
M. Braun-Unkhoff ◽  
P. Frank
Keyword(s):  
Heat Release ◽  
Turbulent Combustion ◽  
Reaction Mechanisms ◽  
Gas Turbines ◽  
Laminar Flame ◽  
Laminar Flame Speed ◽  
Preheat Temperature ◽  
Reduced Mechanism ◽  
Wide Range ◽  
Syngas Combustion

Two reduced reaction mechanisms were established which predict reliably for pressures up to about 20 bar the heat release for different syngas mixtures including initial concentrations of methane. The mechanisms were validated on the base of laminar flame speed data covering a wide range of preheat temperature, pressure and fuel-air mixtures. Additionally, a global reduced mechanism for syngas, which comprises only two steps, was developed and validated, too. This global reduced and validated mechanism can be incorporated into CFD codes for modelling turbulent combustion in stationary gas turbines.

Reduced Reaction Mechanisms for Methane and Syngas Combustion in Gas Turbines

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
N. Slavinskaya ◽  
M. Braun-Unkhoff ◽  
P. Frank
Keyword(s):  
Heat Release ◽  
Turbulent Combustion ◽  
Reaction Mechanisms ◽  
Gas Turbines ◽  
Laminar Flame ◽  
Laminar Flame Speed ◽  
Preheat Temperature ◽  
Reduced Mechanism ◽  
Wide Range ◽  
Syngas Combustion

Two reduced reaction mechanisms were established that predict reliably for pressures up to about 20bar the heat release for different syngas mixtures including initial concentrations of methane. The mechanisms were validated on the base of laminar flame speed data covering a wide range of preheat temperature, pressure, and fuel-air mixtures. Additionally, a global reduced mechanism for syngas, which comprises only two steps, was developed and validated, too. This global reduced and validated mechanism can be incorporated into CFD codes for modeling turbulent combustion in stationary gas turbines.

Laminar Flame Speed Measurements of Synthetic Gas Blends With Hydrocarbon Impurities

2015 ◽  
Author(s):  
Charles L. Keesee ◽  
Eric L. Petersen ◽  
Kuiwen Zhang ◽  
Henry J. Curran
Keyword(s):  
Laminar Flame ◽  
Initial Conditions ◽  
Chemical Kinetic ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Coal Syngas ◽  
Chemical Kinetic Model ◽  
Wide Range ◽  
Synthetic Gas ◽  
Fuel Mixtures

New Laminar Flame Speed measurements have been taken for a wide range of syngas mixtures containing hydrocarbon impurities. These experiments began with two baseline syngas mixtures. The first of these baseline mixtures was a bio-syngas with a 50/50 H2/CO split, and the second baseline mixture was a coal syngas with a 40/60 H2/CO split. Experiments were conducted over a range of equivalence ratios from ϕ = 0.5 to 3 at initial conditions of 1 atm and 300 K. Upon completion of the baseline experiments, two different hydrocarbons were added to the fuel mixtures at levels ranging from 0.8 to 15% by volume, keeping the H2/CO ratio locked for the bio-syngas and coal syngas mixtures. The addition of these light hydrocarbons, namely CH4 and C2H6, had been shown in recent calculations by the authors to have significant impacts on the laminar flame speed, and the present experiments validated the suspected trends. For example, a 7% addition of methane to the coal-syngas blend decreased the peak flame speed by about 25% and shifted it from ϕ = 2.2 to a leaner value near ϕ = 1.5. Also, the addition of ethane at 1.7% reduced the mixture flame speed more than a similar addition of methane (1.6%). In general, the authors’ chemical kinetic model over predicted the laminar flame speed by about 10–20% for the mixtures containing the hydrocarbons. The decrease in laminar flame speed with the addition of the hydrocarbons can be explained by the increased importance of the inhibiting reaction CH3 + H (+M) ↔ CH4 (+M), which also explains the enhanced effect of C2H6 compared to CH4, where the former produces more CH3 radicals, particularly at fuel rich conditions.

scholarly journals Surface Tension and Density of Liquid Hot Work Tool Steel W360 by voestalpine BÖHLER Edelstahl GmbH & Co KG Measured with an Electromagnetic Levitation Apparatus

2020 ◽  
Vol 42 (2) ◽  
Author(s):  
Thomas Leitner ◽  
Anna Werkovits ◽  
Siegfried Kleber ◽  
Gernot Pottlacher
Keyword(s):  
Surface Tension ◽  
Temperature Dependence ◽  
Linear Model ◽  
Tool Steel ◽  
Pure Iron ◽  
Electromagnetic Levitation ◽  
Liquid Density ◽  
Hot Work Tool Steel ◽  
Significant Difference ◽  
Main Component

AbstractW360 is a hot work tool steel produced by voestalpine BÖHLER Edelstahl GmbH & Co KG, a special steel producer located in Styria, Austria. Surface tension and density of liquid W360 were studied as a function of temperature in a non-contact, containerless fashion using the oscillating drop method inside an electromagnetic levitation setup. For both, surface tension and density, a linear model was adapted to present the temperature dependence of these measures, including values for the uncertainties of the fit parameters found. The data obtained are compared to pure iron (with 91 wt% the main component of W360), showing an overlap for the liquid density while there is a significant difference in surface tension (− 5.8 % at the melting temperature of pure iron of 1811 K).

Silver Self-Diffusion in Al2O3/QE22 Magnesium Alloy Matrix Composite

2009 ◽  
Vol 283-286 ◽  
pp. 155-160
Author(s):  
Ivo Stloukal ◽  
Jiří Čermák
Keyword(s):  
Magnesium Alloy ◽  
Temperature Dependence ◽  
Temperature Interval ◽  
Matrix Composite ◽  
Diffusion Coefficients ◽  
Volume Diffusion ◽  
Effective Diffusion ◽  
Measured Temperature ◽  
Alloy Matrix ◽  
Self Diffusion

Self-diffusion of 110mAg has been investigated in fiber reinforced QE22 magnesium alloy matrix composite. Short Saffil fibers (97% -Al2O3 + 3% SiO2) were used as reinforcement. The diffusion measurements were carried out in the temperature interval 648 – 728 K by serial sectioning method. The volume diffusion coefficients Dv (alloy without reinforcement) and the effective diffusion coefficients Deff (alloy with reinforcement) were obtained by analysis of the penetration curves. The silver diffusion coefficient in the interface boundary matrix/Saffil Di was also estimated. The temperature dependence of volume diffusion coefficients Dv was compared with previous data measured using 65Zn in the same alloy and with literature data for Zn impurity diffusion in Mg single crystal. It was observed, that the temperature dependence of both Deff and Di was significantly non-linear in the measured temperature interval. This behavior supports previous observations with zinc diffusion in the same alloy.

Laminar Flame Speeds and Strain Sensitivities of Mixtures of H2∕O2∕N2 at Elevated Preheat Temperatures

2008 ◽  
Vol 130 (6) ◽  
Author(s):  
J. Natarajan ◽  
T. Lieuwen ◽  
J. Seitzman
Keyword(s):  
Kinetic Model ◽  
Temperature Dependence ◽  
Reasonable Agreement ◽  
Room Temperature ◽  
Laminar Flame ◽  
Flame Speed ◽  
Numerical Predictions ◽  
Hydrogen Flame ◽  
Measured Strain ◽  
Lean Conditions

Laminar flame speeds and strain sensitivities of mixtures of H2 and air or air highly diluted with N2 (O2:N2 1:9) have been measured for a range of equivalence ratios at high preheat conditions (∼700K) using a nozzle generated, 1D, laminar, wall stagnation flame. The measurements are compared with numerical predictions based on three detailed kinetic models (GRIMECH 3.0, a H2∕CO mechanism from Davis et al. (2004, “An Optimized Kinetic Model of H2∕CO Combustion,” Proc. Combust. Inst., 30, pp. 1283–1292) and a H2 mechanism from Li et al. (2004, “An Updated Comprehensive Kinetic Model of Hydrogen Combustion,” Int. J. Chem. Kinet., 36, pp. 566–575)). Sensitivity of the measurements to uncertainties in boundary conditions, e.g., wall temperature and nozzle velocity profile (plug or potential), is investigated through detailed numerical simulations and shown to be small. The flame speeds and strain sensitivities predicted by the models for preheated reactants are in reasonable agreement with the measurements for mixtures of H2 and standard air at very lean conditions. For H2 and N2 diluted air, however, all three mechanisms significantly overpredict the measurements, and the overprediction increases for leaner mixtures. In contrast, the models underpredict flame speeds for room temperature mixtures of H2 with both standard and N2 diluted air, based on comparisons with measurements in literature. Thus, we find that the temperature dependence of the hydrogen flame speed as predicted by all the models is greater than the actual temperature dependence (for both standard and diluted air). Finally, the models are found to underpredict the measured strain sensitivity of the flame speed for H2 burning in N2 diluted air, especially away from stoichiometric conditions.

Measurements of Laminar Flame Speeds of Alternative Gaseous Fuel Mixtures

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Ahmed S. Ibrahim ◽  
Samer F. Ahmed
Keyword(s):  
Carbon Dioxide ◽  
Alternative Fuels ◽  
Laminar Flame ◽  
Engine Performance ◽  
Fuel Mixture ◽  
Gaseous Fuel ◽  
Combustion Engines ◽  
Liquefied Petroleum Gas ◽  
Ambient Conditions ◽  
Fuel Mixtures

Global warming and the ever increasing emission levels of combustion engines have forced the engine manufacturers to look for alternative fuels for high engine performance and low emissions. Gaseous fuel mixtures such as biogas, syngas, and liquefied petroleum gas (LPG) are new alternative fuels that have great potential to be used with combustion engines. In the present work, laminar flame speeds (SL) of alternative fuel mixtures, mainly LPG (60% butane, 20% isobutane, and 20% propane) and methane have been studies using the tube method at ambient conditions. In addition, the effect of adding other fuels and gases such as hydrogen, oxygen, carbon dioxide, and nitrogen on SL has also been investigated. The results show that any change in the fuel mixture composition directly affects SL. Measurements of SL of CH4/LPG–air mixtures have found to be about 56 cm/s at ø = 1.1 with 60% LPG in the mixture, which is higher than SL of both pure fuels at the same ø. Moreover, the addition of H2 and O2 to the fuel mixtures increases SL notably, while the addition of CO2/N2 mixture to the fuel mixture, to simulate the EGR effect, decreases SL of CH4/LPG–air mixtures.

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