Chen WT, Jiang Y, Qiu R (2010) Effects of CO Addition on the Lean Premixed CH(4)/Air Flame. Acta Physico-Chimica Sinica 26(6), 1481-1487. [In English]

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Keywords:

CO addition; Laminar burning velocity; NO(x) emission; Extinction strain; rate; burning velocities; diffusion flames; nox emission; methane; combustion; hydrocarbon; extinction; mixtures; ratio

Abstract: A numerical study was carried out to determine the effects of CO addition on the laminar burning velocity, NO(x) emission, and extinction strain rate in a premixed CH(4)/CO/air flame under the lean condition (equivalence ratio of fuel to air phi= 0.60-0.80). When more CO was added to the fuel, the laminar burning velocity decreased, which is different from that observed for H(2) addition. To explain this, we studied the strong correlation between laminar burning velocity and H+OHpeak concentrations. Results showed that the H+ OHpeak concentrations decreased linearly with an increase in CO content. This tendency is in good agreement with that of the laminar burning velocity. For NO(x), we observed that increments in CO addition led to a remarkable reduction in the NO(x) emission. In addition, we investigated the NO formation mechanism and determined the relevant reactions for NO production using a sensitive analysis. The NO concentrations decreased significantly with enrichment by CO and the NO production rate also clearly decreased. We calculated the radial strain rate S(rad) and discussed the influence of strain rate on lean flame stability with regards to the addition of different CO mole fractions to the fuel. The extinction strain rates indicated that the lean flammability limits were extended by CO addition in some way.