Experimental study of the structure of several fuel-rich premixed flames of methane, oxygen, and argon
- Univ. Catholique de Louvain, Louvain la Neuve (Belgium). Lab. de Physico-Chimie de la Combustion
A detailed experimental investigation has been performed on the structures of five low-pressure CH{sub 4}/O{sub 2}/Ar flames at equivalence ratios of 0.92--1.94 (20--60 Torr). Stable compounds, atoms and radicals have been monitored using molecular beam mass spectrometry. The maximum mole fraction of CH{sub 3} radicals is roughly similar in all the flames investigated, whereas those of C{sub 2}H{sub 2}, C{sub 2}H{sub 4}, C{sub 3}H{sub 3}, C{sub 3}H{sub 4} and C{sub 4}H{sub 2} increase strongly with the equivalence ratio. For these species there is a dependence on the equivalence ratio ({Phi}). These results have been supported by a simple kinetic mechanism involving these species. The exponent on {Phi} depends on the species considered and varies as follows: C{sub 4}H{sub 2} > C{sub 2}H{sub 2} >C{sub 3}H{sub 3} > C{sub 3}H{sub 4} > C{sub 2}H{sub 4}. This means that the peak mole fraction of C{sub 4}H{sub 2} increases faster than that of C{sub 3}H{sub 4} with the equivalence ratio. From the net reaction rate of C{sub 2}H{sub 4}, the rate coefficient has been determined for the reaction CH{sub 3} + CH{sub 3} {yields} C{sub 2}H{sub 6}, which is the main process leading to the first C{sub 2} compound. Moreover, it has been established that the formation of C{sub 3}H{sub 4} must proceed through the formation of the propenyl radical C{sub 3}H{sub 5} by reaction between C{sub 2}H{sub 2} and CH{sub 3}. The experimental rate coefficient of this reaction is 5.5 {+-} 2.5 {times} 10{sup 10} cm{sup 3}/mol s at 1,670 K. In addition, disappearance of C{sub 2}H{sub 2}, C{sub 3}H{sub 4} and C{sub 4}H{sub 2} by reaction with H atoms has been examined. The deduced rate coefficients at 1,650 K are 3 {+-} 1 {times} 10{sup 11}, 1.75 {+-} 0.5 {times} 10{sup 12}, 8.1 {+-} 3 {times} cm{sup 3}/mol s, respectively.
- OSTI ID:
- 251082
- Journal Information:
- Combustion and Flame, Vol. 105, Issue 4; Other Information: PBD: Jun 1996
- Country of Publication:
- United States
- Language:
- English
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