Experimental study of the structure of several fuel-rich premixed flames of methane, oxygen, and argon

✍ Scribed by M. Musick; P.J. Van Tiggelen; J. Vandooren

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 1022 KB
• Volume: 105
• Category: Article
• ISSN: 0010-2180
• DOI: 10.1016/0010-2180(95)00228-6

✦ Synopsis

A detailed experimental investigation has been performed on the structures of five low-pressure CH4/O2/Ar flames at equivalence ratios of . Stable compounds, atoms and radicals have been monitored using molecular beam mass spectrometry (MBMS). The maximum mole fraction of CH 3 radicals is roughly similar in all the flames investigated, whereas those of C2H 2, C2H4, C3H3, C3H 4 and C4H 2 increase strongly with the equivalence ratio. For these species there is a dependence on the equivalence ratio (~) in the form (Xi)max = aitYPn' over the equivalence ratios investigated. These results have been supported by a simple kinetic mechanism involving these species. The exponent ni on q~ depends on the species considered and varies as follows: C4H 2 > C2H 2 > C3H 3 > C3H 4 > C2H 4. This means that the peak mole fraction of C4H2 increases faster than that of C3H 4 with the equivalence ratio. From the net reaction rate of C2H4, the rate coefficient has been determined for the reaction CH 3 + CH 3 --+ C2H6, which is the main process leading to the first C 2 compound. Moreover, it has been established that the formation of C3H 4 must proceed through the formation of the propenyl radical C3H5 by reaction between C2H 2 and CH 3. The experimental rate coefficient of this reaction is 5.5 + 2.5 × 10 t° cm 3 mol -~ s -~ at 1670 K. In addition, disappearance of C2H 2, C3H 4 and C4H 2 by reaction with H atoms has been examined. The deduced rate coefficients at 1650 K are 3 + 1 x 101~, 1.75 + 0.5 × 10 ~2, 8.1 + 3 × 10 N cm 3 mol -~ s -I, respectively. This work provides experimental information for further comparison with modeling.