Laminar flame speeds of primary reference fuels and reformer gas mixtures

Huang, Yimin; Sung, Chih-Jen; Eng, J. A.

doi:10.1016/j.combustflame.2004.08.011

Cited by 238 publications

(112 citation statements)

References 22 publications

(52 reference statements)

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“…To assess the accuracy of the chemistry representation, the detailed reaction mechanism is used to estimate flame speeds for n-heptane/air mixtures at different equivalence ratios and unburned gas temperatures at which experimental data are available from the literature (Davis & Law 1998a;Huang, Sung & Eng 2004;Kumar et al 2007;Ji et al 2010;Kelley et al 2011;Van Lipzig et al 2011). The agreement between experiments and simulations is excellent for lean and stoichiometric mixtures as shown in figure 2(a).…”

Section: Reaction Mechanismmentioning

confidence: 70%

Cyclic flame propagation in premixed combustion

et al. 2013

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In experiments of hot surface ignition and subsequent flame propagation, a puffing flame instability is observed in mixtures that are stagnant and premixed prior to ignition. By varying the size of the hot surface, power input, and combustion vessel volume, it was determined that the instability is a function of the interaction of the flame, with the fluid flow induced by the combustion products rather than the initial plume established by the hot surface. Pressure ranges from 25 to 100 kPa and mixtures of n-hexane/air with equivalence ratios between φ = 0.58 and 3.0 at room temperature were investigated. Equivalence ratios between φ = 2.15 and 2.5 exhibited multiple flame and equivalence ratios above φ = 2.5 resulted in puffing flames at atmospheric pressure. The phenomenon is accurately reproduced in numerical simulations and a detailed flow field analysis revealed competition between the inflow velocity at the base of the flame and the flame propagation speed. The increasing inflow velocity, which exceeds the flame propagation speed, is ultimately responsible for creating a puff. The puff is then accelerated upward, allowing for the creation of the subsequent instabilities. The frequency of the puff is proportional to the gravitational acceleration and inversely proportional to the flame speed. A scaling relationship describes the dependence of the frequency on gravitational acceleration, hot surface diameter, and flame speed. This relation shows good agreement for rich n-hexane/air and lean hydrogen/air flames, as well as lean hexane/hydrogen/air mixtures.

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Section: Reaction Mechanismmentioning

confidence: 70%

Cyclic flame propagation in premixed combustion

et al. 2013

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“…In this section, predictions obtained using the mechanism described above are compared against a wide range of experimental data, including shock tube studies [1][2][3][4][5][6][7][8], premixed flames [9][10][11], and species profiles obtained in a variable pressure flow reactor (VPFR) [12,13] and a jet-stirred reactor (JSR) [14,15]. For shock tube ignition delay simulations, the systems were modeled assuming isochoric, homogeneous, and adiabatic conditions.…”

Section: Validationmentioning

confidence: 99%

“…These studies comprise shock tube ignition delays [1][2][3][4][5][6][7][8], premixed laminar-burning velocities [9][10][11], and product speciation in adiabatic plug-flow [12,13], and jet-stirred [14,15] reactors. The systems studied focus primarily on near-stoichiometric conditions and moderate pressures and provide valuable validation data for chemical mechanisms relevant to gasoline SI engines.…”

Section: Introductionmentioning

confidence: 99%

A high‐temperature chemical kinetic model for primary reference fuels

Chaos

Kazakov

Zhao

et al. 2007

Int J of Chemical Kinetics

174

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A chemical kinetic mechanism has been developed to describe the hightemperature oxidation and pyrolysis of n-heptane, iso-octane, and their mixtures. An approach previously developed by this laboratory was used here to partially reduce the mechanism while maintaining a desired level of detailed reaction information. The relevant mechanism involves 107 species undergoing 723 reactions and has been validated against an extensive set of experimental data gathered from the literature that includes shock tube ignition delay measurements, premixed laminar-burning velocities, variable pressure flow reactor, and jetstirred reactor species profiles. The modeled experiments treat dynamic systems with pressures up to 15 atm, temperatures above 950 K, and equivalence ratios less than approximately 2.5. Given the stringent and comprehensive set of experimental conditions against which the model is tested, remarkably good agreement is obtained between experimental and model results.

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“…Therefore, development of coalderived syngas-based combustors is an essential step toward the clean coal technology of IGCC. In addition, reformer gas (H 2 /CO/N 2 mixture) obtained from reforming of hydrocarbon fuels has been proposed as a means of reducing cold start emission of an SI engine [2][3][4]. In view of the above, improvement in overall understanding of H 2 /CO and H 2 combustion and availability of the associated comprehensive kinetic mechanism under extensive parametric variations are expected to represent a significant advance.…”

Section: Introductionmentioning

confidence: 99%

Autoignition of H₂/CO at elevated pressures in a rapid compression machine

Mittal

Sung

Yetter

2006

Int J of Chemical Kinetics

122

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Autoignition of H 2 /O 2 and H 2 /CO/O 2 mixtures has been studied in a rapid compression machine at pressures from 15 to 50 bar, temperatures from 950 to 1100 K, and equivalence ratios from 0.36 to 1.6. In addition, the effect of change in relative concentrations of H 2 and CO is investigated by replacing H 2 with CO, while keeping the total fuel mole fraction of the combined H 2 /CO fuel constant. Under the experimental conditions of intermediate temperature and high pressure, reactions involving formation and consumption of HO 2 and H 2 O 2 are important. Results show that for H 2 autoignition, the mechanism of O'Conaire et al. agrees well with the experimental data, although some improvements can still be made. At all the pressures investigated, replacement of some amount of H 2 by CO in a reacting mixture leads to an increase in ignition delay, even with small amounts of CO addition. The inhibition effect of CO addition is also observed to be much more pronounced with increasing pressure. For H 2 /CO mixtures, the existing mechanisms of Li et al., Davis et al., and GRI-Mech 3.0 fail to describe the experimental trend of ignition delay. At a pressure of 50 bar, ignition delays are seen to decrease monotonically with O 2 addition, although such an effect is rather weak. Kinetic analysis further demonstrates that under the present experimental conditions, CO + HO 2 = CO 2 + OH is the primary reaction responsible for the mismatch of experimental and calculated ignition delays. Significant improvements in the ignition delay predictions can be made by reducing this reaction rate.

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Laminar flame speeds of primary reference fuels and reformer gas mixtures

Cited by 238 publications

References 22 publications

Cyclic flame propagation in premixed combustion

Cyclic flame propagation in premixed combustion

A high‐temperature chemical kinetic model for primary reference fuels

Autoignition of H₂/CO at elevated pressures in a rapid compression machine

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Laminar flame speeds of primary reference fuels and reformer gas mixtures

Cited by 238 publications

References 22 publications

Cyclic flame propagation in premixed combustion

Cyclic flame propagation in premixed combustion

A high‐temperature chemical kinetic model for primary reference fuels

Autoignition of H2/CO at elevated pressures in a rapid compression machine

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Product

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Autoignition of H₂/CO at elevated pressures in a rapid compression machine