Reduced NO formation models for CFD simulations of MILD combustion

• Reduced kinetic schemes including thermal, N2O, NNH and HNO/NO2 intermediate routes.
• Rate of production analysis in MILD combustion conditions.
• Comparison with other schemes from literature and experimental NO.
• Strong impact of NNH intermediate route.

Two reduced kinetic models, incorporating thermal, N2O, NNH as well as HNO/NO2 intermediate routes, are proposed for the quick evaluation of NO emissions from MILD combustion of H2-enriched fuels through post-processing of Computational Fluid Dynamics simulations. The models were derived from a Rate Of Production Analysis carried out with two different detailed kinetic schemes. The models were tested using data from the Adelaide Jet in Hot Coflow burner fed with CH4/H2 mixture and operated with three different O2 contents. Very satisfactory predictions of in-flame NO measurements were achieved for the three cases, indicating a good applicability of the models across a wide range of MILD combustion conditions. Significant impact of the NNH intermediate path was observed.