Fuel injection effects on distribution reaction in a high intensity combustor

• Colorless distributed combustion.
• Dual location fuel injection.
• NO∗-OH∗ chemiluminescence.
• Ultra-low NO-CO emissions.

The role of dual location fuel injection (versus single injection) is examined for improved mixture preparation with enhanced reaction distribution in the combustor that offers reduced emissions. A cylindrical combustor was used at a combustion intensity of 36 MW/m3 atm and heat load of 6.25 kW. Three different configurations were examined for the effect of dual location fuel injection using methane as the fuel. NO reduction of 48% was achieved with fuel injected at two locations versus single location at an overall equivalence ratio of 0.7. The OH∗ Chemiluminescence intensity distribution with dual location fuel injection showed the reaction zone to shift further downstream that provided longer fuel mixture preparation time prior to ignition under favorable fuel distribution conditions. The longer mixing time helped to improve mixture preparation with lower emissions. The NO∗ chemiluminescence signatures supported the results obtained on reduced NO emission. Mean to maximum OH∗ signal showed that dual location fuel injection enhanced distributed reaction at certain fuel distributions between the two locations (fuel injection ratio lower than 70%) for all the three configurations examined. Increase in air injection velocity from 46 m/s to 102 m/s showed up to 85% NO reduction utilizing dual location fuel injection without any increase in CO emission. Increase in air preheats from 300 K to 600 K reduced the extent of NO reduction. Dual location fuel injection provided improved reaction zone distribution in the combustor for all the experimental conditions reported here. Correlations are provided that describes the NOX emission as function of fuel injection ratio.