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Radical species profiles in low-pressure methane flames containing fuel nitrogen compounds

Journal Article · · Combustion and Flame
;  [1]
  1. Naval Research Lab., Washington, DC (United States). Chemistry Div.
Relative concentration profiles of CN, NH, NCO, NH{sub 2}, and NO are recorded for a 10 torr, premixed CH{sub 4}O{sub 2}Ar flame doped with the following compounds: 0.35% NH{sub 3}, CH{sub 3}NH{sub 2}, and CH{sub 3}CN, and 0.86% NO. Profiles were measured by laser-induced fluorescence and compared between the different dopants. The experimental data are compared to detailed kinetic calculations based on the Gas Research Institute Mechanism 2.11 for the NH{sub 3} and NO dopants, with added submechanisms for CH{sub 3}CH and CH{sub 3}NH{sub 2}. The kinetic model underpredicts the amount of CN and NCO formed from the ammonia dopant; if the authors postulate a reaction between CH{sub 3} and NH, these discrepancies are largely resolved. Comparison of CN and NCO profiles between the NO and NH{sub 3} dopants indicates that HCN is the primary product of the CH + NOO reaction. Extrapolation of measured rates for CH{sub 3}CN destruction reactions to combustion temperatures predicts a rate of CH{sub 3}CN removal which is far too slow. Previously published mechanisms for methylamine combustion overpredict the amount of NH{sub 2} produced, indicating that cleavage of the C-N bond is less likely in the initial attack than the kinetic mechanisms predict. The authors propose modifications to the CH{sub 3}CN and CH{sub 3}NH{sub 2} submechanisms which correct these deficiencies and lead to good agreement with the measured intermediate profiles for all dopants.
OSTI ID:
543425
Journal Information:
Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 1-2 Vol. 110; ISSN CBFMAO; ISSN 0010-2180
Country of Publication:
United States
Language:
English