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Title: Absolute CH radical concentrations in rich low-pressure methane-oxygen-argon flames via cavity ringdown spectroscopy of the A{sup 2}{Delta}-X{sup 2}II transition

Abstract

The authors measure absolute methylidyne (CH) radical concentrations in a series of rich 31.0 Torr (4.13 kPa) methane-oxygen-argon flames using cavity ringdown spectroscopy. Probing via the CH A{sup 2}{Delta}-X{sup 2}II transition near 430 nm gives a sensitivity of 3 x 10{sup 9 cm{sup {minus}3}} for experimental conditions, yielding a signal-to-noise ratio greater than 1,000 for the strongest transitions observed. The authors measure profiles of CH mole fraction as a function of height above a flat-flame burner for rich flames with equivalence ratios of 1.0, 1.2, 1.4, and 1.6. These flames are modeled using the following mechanisms: (1) the GRI Mech 2.11, (2) a mechanism by Prada and miller, (3) a modified GRI 2.11 mechanism, which employs a more realistic increased CH + O{sub 2} rate coefficient, and (4) the new GRI Mech 3.0. Generally good agreement between the models and the data is found, with the GRI 3.0 and modified 2.11 mechanisms best reproducing the data. The greatest discrepancies are observed at the richest stoichiometry, where all of the models predict a wider CH profile shifted further from the burner than experimentally observed.

Authors:
;
Publication Date:
Research Org.:
Williams Coll., Williamstown, MA (US)
Sponsoring Org.:
USDOE
OSTI Identifier:
20075884
Resource Type:
Journal Article
Journal Name:
Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory
Additional Journal Information:
Journal Volume: 104; Journal Issue: 21; Other Information: PBD: 1 Jun 2000; Journal ID: ISSN 1089-5639
Country of Publication:
United States
Language:
English
Subject:
03 NATURAL GAS; RADICALS; ABUNDANCE; METHANE; OXYGEN; ARGON; COMBUSTION KINETICS; ENERGY-LEVEL TRANSITIONS; REACTION INTERMEDIATES

Citation Formats

Thoman, J.W. Jr., and McIlroy, A. Absolute CH radical concentrations in rich low-pressure methane-oxygen-argon flames via cavity ringdown spectroscopy of the A{sup 2}{Delta}-X{sup 2}II transition. United States: N. p., 2000. Web. doi:10.1021/jp0001687.
Thoman, J.W. Jr., & McIlroy, A. Absolute CH radical concentrations in rich low-pressure methane-oxygen-argon flames via cavity ringdown spectroscopy of the A{sup 2}{Delta}-X{sup 2}II transition. United States. doi:10.1021/jp0001687.
Thoman, J.W. Jr., and McIlroy, A. Thu . "Absolute CH radical concentrations in rich low-pressure methane-oxygen-argon flames via cavity ringdown spectroscopy of the A{sup 2}{Delta}-X{sup 2}II transition". United States. doi:10.1021/jp0001687.
@article{osti_20075884,
title = {Absolute CH radical concentrations in rich low-pressure methane-oxygen-argon flames via cavity ringdown spectroscopy of the A{sup 2}{Delta}-X{sup 2}II transition},
author = {Thoman, J.W. Jr. and McIlroy, A.},
abstractNote = {The authors measure absolute methylidyne (CH) radical concentrations in a series of rich 31.0 Torr (4.13 kPa) methane-oxygen-argon flames using cavity ringdown spectroscopy. Probing via the CH A{sup 2}{Delta}-X{sup 2}II transition near 430 nm gives a sensitivity of 3 x 10{sup 9 cm{sup {minus}3}} for experimental conditions, yielding a signal-to-noise ratio greater than 1,000 for the strongest transitions observed. The authors measure profiles of CH mole fraction as a function of height above a flat-flame burner for rich flames with equivalence ratios of 1.0, 1.2, 1.4, and 1.6. These flames are modeled using the following mechanisms: (1) the GRI Mech 2.11, (2) a mechanism by Prada and miller, (3) a modified GRI 2.11 mechanism, which employs a more realistic increased CH + O{sub 2} rate coefficient, and (4) the new GRI Mech 3.0. Generally good agreement between the models and the data is found, with the GRI 3.0 and modified 2.11 mechanisms best reproducing the data. The greatest discrepancies are observed at the richest stoichiometry, where all of the models predict a wider CH profile shifted further from the burner than experimentally observed.},
doi = {10.1021/jp0001687},
journal = {Journal of Physical Chemistry A: Molecules, Spectroscopy, Kinetics, Environment, amp General Theory},
issn = {1089-5639},
number = 21,
volume = 104,
place = {United States},
year = {2000},
month = {6}
}