Experimental and modeling study of the effects of equivalence ratio on the benzene formation chemistry of one-dimensional laminar premixed n-heptane flames

Gen Chen*, Wu Yu, Jin Fu, Zuohua Huang, Jiuzhong Yang, Zhandong Wang, Fei Qi

*Corresponding author for this work

Research output: Contribution to conferencePaperpeer-review

Abstract

In order to gain a better understanding of the soot formation mechanism involved in the combustion process of hydrocarbon fuels, laminar premixed n-heptane flames with different equivalence ratios (1.20, 1.60 and 1.80) are studied by using synchrotron photoionization and molecular-beam mass spectrometry (PI-MBMS) techniques at low pressure(30Torr). To isolate the influence from flame temperature, the composition of unburned mixtures is adjusted such that the temperature profiles are approximately equivalent. Mole fraction profiles of major and intermediate species were derived and compared among different flames. Parallel modeling study based on a modified mechanism is conducted. The predicted mole fraction profiles of concerned species agree reasonably well with experimental measurements. The results show that, as equivalence ratio increases, the equilibrium mole fractions of H2O and CO2 decrease while those of H2 and CO increase, and the concentrations of benzene and toluene and those of C2-C 5 hydrocarbon intermediates increase apparently. The reaction flux analysis indicates that the self-recombination of propargyl radical (C 3H3) and the cross reaction between C3H 3 and allyl radical (a-C3H5) are the dominant pathway leading from small aliphatics to C6H6. The consumption of C6H6 is primarily resulted from the attack by OH and H radicals. The larger amount of C6H6 formed in richer flames should be attributed mainly to the higher concentrations of benzene precursors. In addition, the weakening influence of the OH-attack and O-attack reaction tends to slow down the consumption of C6H 6, which also contributes to the higher C6H6 concentration in the richer flames.

Original languageEnglish (US)
Pages226-231
Number of pages6
StatePublished - Dec 1 2012
Event8th International Conference on Modeling and Diagnostics for Advanced Engine Systems, COMODIA 2012 - Fukuoka, Japan
Duration: Jul 23 2012Jul 26 2012

Other

Other8th International Conference on Modeling and Diagnostics for Advanced Engine Systems, COMODIA 2012
CountryJapan
CityFukuoka
Period07/23/1207/26/12

Keywords

  • Benzene chemistry
  • Kinetic modeling
  • Molecular-beam sampling-mass spectrometry (MBMS)
  • N-heptane premixed flame
  • Tunable synchrotron photoionization

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Modeling and Simulation

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