Experimental and modeling studies of the micro-structures of opposed flow diffusion flames: Methane

The micro-structure of an atmospheric pressure, opposed flow, methane diffusion flame has been studied using heated micro-probe sampling and chemical kinetic modeling. Mole fraction profiles of major products as well as trace aromatic, substituted aromatic, and polycyclic aromatic hydrocarbons (PAH up to C{sub 16}H{sub 10}, e.g. pyrene) were quantified by direct gas chromatography/mass spectrometry (GC/MS) analysis of samples withdrawn from within the flame without any pre-concentration. Mole fractions range from 0.8 to 1.0 {times} 10{sup {minus}7}. The experimental measurements are compared to results from a newly-developed chemical kinetic model that includes chemistry for the production and consumption of aromatics and PAH species. The model predictions are in reasonable agreement with the experimental data for the major species profiles and for the peak concentrations of many of the trace aromatics and PAH species. 36 refs

Chemical kinetic modeling of a methane opposed flow diffusion flame and comparison to experiments

The chemical structure of an opposed flow, methane diffusion flame is studied using a chemical kinetic model and the results are compared to experimental measurements. The chemical kinetic paths leading to aromatics and polycyclic aromatics hydrocarbons (PAHs) in the diffusion flame are identified. These paths all involve resonantly stabilized radicals which include propargyl, allyl, cyclopentadienyl, and benzyl radicals. The modeling results show reasonable agreement with the experimental measurements for the large hydrocarbon aliphatic compounds, aromatics, and PAHs. the benzene was predicted to be formed primarily by the reaction sequence of Allyl plus Propargyl equals Fulvene plus H plus H followed by fulvene isomerization to benzene. Naphthalene was modeled using the reaction of benzyl with propargyl, while the combination of cyclopentadienyl radicals were shown to be a minor contributor in the diffusion flame. The agreement between the model and experiment for the four-ring PAHs was poor