The combustion with oxygen enriched air has a potential of the fuel savings and the consequent reduction of carbon dioxide emission. The fuel savings were examined by the enthalpy of equilibrium state in case of oxygen enriched combustion. The fuel consumption in case of 30-40% oxygen enriched air is reduced by 20-30% as compared with the case of 21% oxygen air. However, NO emission increases with the enrichment of oxygen in the air. The effect of oxygen enriched air on NO emission in the methane premix flame was numerically analyzed with detailed chemistry for the equivalent ratio of 0.5-2.0 The results revealed that the low NOx combustion with 30% oxygen enriched air can be achieved in case of the fuel lean (φ<0.6) or fuel rich (φ>1.5) condition. It was also shown that the burning velocity with oxygen enriched air is considerably high even at the fuel lean and fuel rich condition.

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The combustion with oxygen enriched air has a potential of the fuel savings and the consequent reduction of carbon dioxide emission. The fuel savings were examined by the enthalpy of equilibrium state in case of oxygen enriched combustion. The fuel consumption in case of 30-40% oxygen enriched air is reduced by 5.9-9.1% as compared with the case of 21% oxygen air at exhaust temperature 773K after whichsensible heat of exhaust gas exchange the sensible heat of combustion air. However, NO emission increases with the enrichment of oxygen in the air and the increase of initial temperature. The effect of oxygen enriched air and initial temperature on NO emissions in the methane premix flame was numerically analyzed with detailed chemistry for the equivalent ratio of 0.5-2.0. The results revealed that the low NOx combustion with 30% oxygen enriched air can be achieved in case of the fuel rich (φ>2.0) condition. Furthermore, the effect of oxygen enriched air and entrainment of exhaust gas was analyzed numerically. The low NOx combustion with 30% oxygen enriched air and initial temperature 798K can be achieved in case of the fuel lean (φ<0.5) or fuel rich (φ>1.5) condition and mixing ratio 0.5 which is expressed that the ratio mole of exhaust gas against the mole of fuel and oxygen enriched air.

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