Experimental and modeling study of the oxidation of natural gas in a premixed flame, shock tube, and jet-stirred reactor

Abstract

New experimental results have been obtained for the oxidation of a stoichiometric premixed synthetic natural gas flame at low pressure (10.6 kPa). Mole fraction profiles of stable and reactive species and temperature were measured using molecular beam/mass spectrometry, gas chromatography, and thermocouple techniques. A detailed reaction mechanism has been evaluated by comparison of computed and measured species mole fraction profiles. Good agreement was obtained for most molecular species (reactants, intermediate species, and final products). The proposed mechanism was also validated by modeling the laminar flame speeds of methane/air, ethane/air, and propane/air flames reported in the literature over a wide range of equivalence ratios. The model reproduces correctly the experimental values. The model was also used to simulate new experimental results obtained in a jet-stirred reactor (JSR) at atmospheric pressure and variable equivalence ratio ( Φ=0.75:1.0:1.5) for the oxidation of methane–ethane mixtures representative of natural gas. The ignition delays of methane–oxygen–argon and methane–ethane–oxygen were modeled. Sensitivity analyses and reaction path analyses, based on species rates of reaction, were used to interpret the results, especially the effect of higher alkanes on the oxidation of natural gas.