Luminescence from hydrogen-fluorine flames, dilute in methane

Journal Article · Fri Nov 01 04:00:00 EST 1991 · Combustion and Flame; (United States)

DOI:https://doi.org/10.1016/0010-2180(91)90163-6· OSTI ID:5272901

Moore, C; Erickson, M; Kaufman, M ^[1]

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1. Dept. of Chemistry, Emory Univ., Atlanta, GA (US)

Besides the inherent interest of fluorine-supported combustion for lasers and advance propulsion systems, such flames are also important for what they can reveal about combustion processes in general. Mechanisms producing luminescence from Ch, C{sub 2} and CHF in Ch{sub 4}-F{sub 2} flames are studied by the method of very dilute flames, whereby small amounts of CH{sub 4} (below 2%) are added to H{sub 2}-F{sub 2} flames. This techniques allows the dependence of the emission intensities on the concentration of CH{sub 4} and carbon-containing radicals to be separated from its dependence on equivalence ratio and pressure, which determines flame temperature and the concentration of hydrogen and fluorine atoms. The most likely mechanism for C{sub 2} emission is the reaction of two CH radicals, while CH emission (both A and B states) and CHF emission probably result from vibration-to-electronic (V-E) energy transfer from vibrationally excited Hf. Experiments using CD{sub 4} and D{sub 2} are in agreement with the mechanism proposed for CH emission. The isotope experiments, as well as laser-induced florescence measurements on CH, indicate that the V-E energy transfer is by a single step, rather than by stepwise excitation up the vibrational ladder of CH(X). In this paper a diagnostics for the (F)/(F{sub 2}) ratio in F{sub 2-H}{sub 2} or F{sub 2}-hydrocarbon combustion is suggested. The mechanisms proposed for CH and C{sub 2} luminescence are different from those generally discussed for the same emissions in oxygen-supported combustion.

• OSTI ID: 5272901
• Journal Information: Combustion and Flame; (United States), Journal Name: Combustion and Flame; (United States) Vol. 87:2; ISSN CBFMA; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

08 HYDROGEN
083000 -- Hydrogen-- Combustion-- (1990-)
09 BIOMASS FUELS
092000 -- Biomass Fuels-- Combustion-- (1990-)
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400800* -- Combustion
Pyrolysis
& High-Temperature Chemistry
ALKANES
CARBON
CHEMICAL REACTION KINETICS
CHEMILUMINESCENCE
COMBUSTION KINETICS
ELEMENTS
EMISSION SPECTRA
EMISSION SPECTROSCOPY
ENERGY TRANSFER
EQUIVALENCE PRINCIPLE
FLAMES
FLUORESCENCE SPECTROSCOPY
FLUORINE
HALOGENS
HYDROCARBONS
HYDROGEN
KINETICS
LUMINESCENCE
METHANE
NONMETALS
ORGANIC COMPOUNDS
REACTION KINETICS
SPECTRA
SPECTROSCOPY
TEMPERATURE GRADIENTS