Which Fluent combustion model is most appropriate for the natural gas combustion in the high power burners used in the big industrial glass melting furnaces? The gas consist mainly of the methane. The fuel economy of the gas is about 0,5kg.s-1 per burner. The exit temperature of the pollution is expected to be 2200K but I can't get less than 2800? I tried to set Cp temp. dependent and different radiation models but it didn't decrease the temperature. What radiation model is suitable? How high is the emisivity of the average flame? What else maybe should i set?

use flamelet model to start and EDC is best for natural gases.