Flammability limit and limit-temperature of counterflow lean methane-air flames

Journal Article · Sat Jul 01 04:00:00 EDT 1995 · Combustion and Flame

DOI:https://doi.org/10.1016/0010-2180(95)00028-5· OSTI ID:89636

Chen, Z H; Sohrab, S H ^[1]

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1. Northwestern Univ., Evanston, IL (United States). Dept. of Mechanical Engineering

The temperatures of the symmetric counterflow lean methane premixed flames as a function of the fuel mole fraction were measured for four different mean nozzle velocities. The experimental procedure resulted in twin flames that are further separated from each other thereby reducing the effects of incomplete combustion of carbon monoxide induced by downstream diffusional interaction of CO concentration profiles prior to the flame extinction. The limit concentration of fuel for counterflow twin lean methane-air flames was found to be 4.5% instead of the 4.8% obtained from prior investigations. Also, a procedure was described for evaluation of the limit temperature of counterflow lean methane-air flames. The resulting limit temperature of about T{sub f} = 855 C instead of 1,120 C was found to be in closer agreement with the critical crossover temperature of about {Tc} = 780 C at which the rates of certain important chain-branching and chain-terminating reactions become equal to each other. The findings support the idea that the chemical-kinetic mechanisms in terms of competition between certain important chain-branching and chain-terminating reaction steps are of primary importance in defining the critical limit temperature at the lean flammability limit of methane-air premixed flames.

• OSTI ID: 89636
• Journal Information: Combustion and Flame, Journal Name: Combustion and Flame Journal Issue: 1-2 Vol. 102; ISSN CBFMAO; ISSN 0010-2180
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
COMBUSTION KINETICS
DETONATION LIMITS
EXPERIMENTAL DATA
FLAMES
FUEL-AIR RATIO
INHIBITION
METHANE
TEMPERATURE MEASUREMENT