Fundamental Combustion Characteristics of Lean and Stoichiometric Hydrogen Laminar Premixed Flames Diluted With Nitrogen or Carbon Dioxide

2016 ◽  
Vol 138 (11) ◽  
Author(s):  
Hong-Meng Li ◽  
Guo-Xiu Li ◽  
Zuo-Yu Sun ◽  
Zi-Hang Zhou ◽  
Yuan Li ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Equivalence Ratio ◽  
Burning Velocity ◽  
Flame Temperature ◽  
Premixed Flames ◽  
Combustion Characteristics ◽  
Inert Gas ◽  
Chemical Effect ◽  
Laminar Burning Velocity ◽  
Suppression Effect

In this work, the laminar combustion characteristics of H2/N2/air (H2/CO2/air) were systematically investigated under different hydrogen ratios (40–100%) and equivalence ratios (0.4–1.0) in a closed combustion vessel using the spherical expanding flame method associated with Schlieren technology. The unstretched laminar burning velocities were compared with data from previous study, and the result indicates that excellent agreements are obtained. Numerical simulations were also conducted using GRI3.0 and USC II mechanisms to compare with the present experimental results. The Markstein length for H2/inert gas can be decreased by decreasing the equivalence ratio and hydrogen ratio. The results indicate that the H2/inert gas premixed flames tend to be more unstable with the decrease of equivalence ratio and hydrogen ratio. For H2/N2 mixture, the suppression effect on laminar burning velocity is caused by modified specific heat of mixtures and decreased heat release, which result in a decreased flame temperature. For H2/CO2 mixture, the carbon dioxide has stronger dilution effect than nitrogen in reducing laminar burning velocity owing to both thermal effect and chemical effect.

Effects of N2 dilution on laminar burning velocity, combustion characteristics and NOx emissions of rich CH4–air premixed flames

Fuel ◽  
2021 ◽  
Vol 284 ◽  
pp. 119017 ◽  
Author(s):  
Huaqiang Chu ◽  
Longkai Xiang ◽  
Shun Meng ◽  
Wenlong Dong ◽  
Mingyan Gu ◽  
...  
Keyword(s):  
Burning Velocity ◽  
Premixed Flames ◽  
Combustion Characteristics ◽  
Nox Emissions ◽  
Laminar Burning Velocity

Characteristics of Ammonia-Nitric Oxide Combustion

2003 ◽  
Author(s):  
Rui Liu ◽  
David S.-K. Ting ◽  
M. David Checkel
Keyword(s):  
Nitric Oxide ◽  
Reaction Mechanisms ◽  
Equivalence Ratio ◽  
Burning Velocity ◽  
Flame Temperature ◽  
Laminar Burning Velocity ◽  
Flammability Limits ◽  
Constant Volume Combustion Chamber ◽  
Experimental Values ◽  
Peak Value

The combustion characteristics of premixed ammonia-nitric oxide mixtures at atmospheric and elevated conditions were numerically examined. The laminar burning velocity, flame temperature and flammability limits were determined using the GRI 3.0 and the Miller-Bowman 1989 reaction mechanisms in CHEMKIN. A freely propagating adiabatic flame was assumed to facilitate the investigation. The laminar burning velocities and the flammability limits predicted with the two mechanisms were compared with experimental values measured in a constant volume combustion chamber. The predicted flammability limits are at ammonia-nitric oxide equivalence ratios of 0.2 and 3.5. The predicted laminar burning velocity increases with the unburnt mixture temperature and decreases with the pressure with a peak value at ammonia-nitric oxide equivalence ratio of 0.9. The Miller-Bowman 1989 mechanism predicts results closer to the measured values than the GRI 3.0 mechanism when the laminar burning velocity is concerned. For the adiabatic flame temperature, the predictions from both mechanisms agree well with each other.

The Effect of Impurities in Fuel Grade Dimethyl-Ether on Combustion Characteristics

2004 ◽  
Author(s):  
Kimihito Narukawa ◽  
Hiromi Koizumi ◽  
Hiroshi Inoue ◽  
Nariyoshi Kobayashi
Keyword(s):  
Dimethyl Ether ◽  
Diffusion Flame ◽  
High Purity ◽  
Burning Velocity ◽  
Flame Temperature ◽  
Combustion Characteristics ◽  
Nox Emissions ◽  
Laminar Burning Velocity ◽  
Gas Turbine Combustor ◽  
Effect Of Impurities

In order to investigate the effect of impurities contained in fuel grade dimethyl-ether on combustion characteristics, laminar burning velocity tests and diffusion flame combustor tests were carried out with various contents of impurities in fuel grade dimethyl-ether (with about 0–9wt% methanol and 0–10wt% moisture). From the laminar burning velocity tests, it was found that the burning velocity of fuel grade dimethyl-ether was slightly slower than that of high purity dimethyl-ether and it was faster than that of methane. This indicates that fuel grade dimethyl-ether has a high potential of flash back, like high purity dimethyl-ether. Moreover, the diffusion flame combustor tests showed that NOx emission decreased when the impurities contained in fuel grade dimethyl-ether were increased, however CO emissions were almost constant, irrespective of the content of impurities. Further, by comparing NOx emissions with various contents of impurities in fuel grade dimethyl-ether, it was clear that NOx emissions could be estimated from the adiabatic flame temperature. From these results, a lot of valuable data regarding impurities content has been obtained, which will assist in the development of a gas turbine combustor for fuel grade dimethyl-ether.

Experimental and Numerical Study on Diluted Premixed Laminar Dimethyl Ether-Air Flames

2013 ◽  
Vol 732-733 ◽  
pp. 18-22
Author(s):  
Zhao Yang Chen ◽  
Chong Long Tang
Keyword(s):  
Carbon Dioxide ◽  
Dimethyl Ether ◽  
Laminar Flame ◽  
Numerical Study ◽  
Burning Velocity ◽  
Direct Reaction ◽  
Laminar Burning Velocity ◽  
Suppression Effect ◽  
Premixed Laminar ◽  
Good Agreement

Effects of diluents on premixed laminar dimethyl ether (DME)/air flames were studied experimentally and numerically. The results show that measurements and predictions in laminar burning velocities are in reasonably good agreement. Laminar flame speeds of DME mixtures decrease with the increase of dilution ratio. For a specific diluent ratio, suppression effect of diluent decreases in the order of carbon dioxide, nitrogen and argon. Influences of argon and nitrogen are mainly due to the increase of specific heat of the non-fuel gases in the mixture, and that of carbon dioxide is resulted from the combination effect of dilution and direct reaction. CO2 participating reaction, CO+OHCO2+H, competes for H radical in the chain branching reaction H+O2 O+OH. This competition decreases concentration of the radicals like H, O and OH, leading to a significant reduction in laminar burning velocity.

Numerical Analysis of Equivalence Ratio Fluctuations in a Partially Premixed Gas Turbine Combustor Using Large Eddy Simulations

2018 ◽  
Vol 141 (4) ◽  
Author(s):  
Ping Wang ◽  
Qian Yu ◽  
Prashant Shrotriya ◽  
Mingmin Chen
Keyword(s):  
Reaction Mechanism ◽  
Equivalence Ratio ◽  
Flame Temperature ◽  
Premixed Flames ◽  
Large Eddy Simulations ◽  
Combustion Model ◽  
Inlet Channel ◽  
Large Eddy ◽  
Partially Premixed Flames ◽  
Partially Premixed

In the present work, the fluctuations of equivalence ratio in the PRECCINSTA combustor are investigated via large eddy simulations (LES). Four isothermal flow cases with different combinations of global equivalence ratios (0.7 or 0.83) and grids (1.2 or 1.8 million cells) are simulated to study the mixing process of air with methane, which is injected into the inlet channel through small holes. It is shown that the fluctuations of equivalence ratio are very large, and their ranges are [0.4, 1.3] and [0.3, 1.2] for cases 0.83 and 0.7, respectively. For simulating turbulent partially premixed flames in this burner with the well-known dynamically thickened flame (DTF) combustion model, a suitable multistep reaction mechanism should be chosen aforehand. To do that, laminar premixed flames of 15 different equivalence ratios are calculated using three different methane/air reaction mechanisms: 2S_CH4_BFER, 2sCM2 reduced mechanisms and GRI-Mech 3.0 detailed reaction mechanism. The variations of flame temperature, flame speed and thickness of the laminar flames with the equivalence ratios are compared in detail. It is demonstrated that the applicative equivalence ratio range for the 2S_CH4_BFER mechanism is [0.5, 1.3], which is larger than that of the 2sCM2 mechanism [0.5, 1.2]. Therefore, it is recommended to use the 2S_CH4_BFER scheme to simulate the partially premixed flames in the PRECCINSTA combustion chamber.

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