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Soot Formation in Laminar Premixed Ethylene/Air Flames at Atmospheric PressureSoot formation was studied within laminar premixed ethylene/air flames (C/O ratios of 0.78-0.98) stabilized on a flat-flame burner operating at atmospheric pressure. Measurements included soot volume fractions by both laser extinction and gravimetric methods, temperatures by multiline emission, soot structure by thermophoretic sampling and transmission electron microscopy, major gas species concentrations by sampling and gas chromatography, concentrations of condensable hydrocarbons by gravimetric sampling. and velocities by laser velocimetry. These data were used to find soot surface growth rates and primary soot particle nucleation rates along the axes of the flames. Present measurements of soot surface growth rates were correlated successfully by predictions based on typical hydrogen-abstraction/carbon-addition (HACA) mechanisms of Frenklach and co-workers and Colket and Hall. These results suavest that reduced soot surface growth rates with increasing residence time seen in the present and other similar flames were mainly caused by reduced rates of surface activation due to reduced H atom concentrations as temperatures decrease as a result of radiative heat losses. Primary soot particle nucleation rates exhibited variations with temperature and acetylene concentrations that were similar to recent observations for diffusion flames; however, nucleation rates in the premixed flames were significantly lower than in, the diffusion flames for reasons that still must be explained. Finally, predictions of yields of major gas species based on mechanisms from both Frenklach and co-workers and Leung and Lindstedt were in good agreement with present measurements and suggest that H atom concentrations (relevant to HACA mechanisms) approximate estimates based on local thermodynamic equilibrium in the present flames.
Document ID
20020087748
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Xu, F.
(Michigan Univ. Ann Arbor, MI United States)
Sunderland, P. B.
(Michigan Univ. Ann Arbor, MI United States)
Faeth, G. M.
(Michigan Univ. Ann Arbor, MI United States)
Urban, D. L.
Date Acquired
August 20, 2013
Publication Date
December 15, 2001
Publication Information
Publication: Soot Formation in Freely-Propagating Laminar Premixed Flames
ISSN: 0010-2180
Subject Category
Inorganic, Organic And Physical Chemistry
Funding Number(s)
CONTRACT_GRANT: NAG3-1245
CONTRACT_GRANT: N00014-93-0321
Distribution Limits
Public
Copyright
Other

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