The effects of nitrogen and argon dilution on NO X emission of turbulent propane-air non-premixed flame in a furnace are experimentally investigated. Dilution is an effective process in reducing NO X emission, since diluents cause an increase in the mass flow of the fuel, and consequently the temperature in the combustion chamber and NO X emission decreases. We measured NO X emission and temperature for a wide range of dilution and equivalence ratios. The results show that nitrogen dilution is more effective than argon dilution in reducing NO X emission. In addition, both dilutions caused the yellow color of the non-premixed flame to turn blue, which indicates more complete combustion and better mixing of fuel and oxidant.

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