Reduced Reaction Mechanisms for Ammonia Oxidation in Premixed Laminar Flames

Abstract Reduced reaction mechanisms are essential for the inclusion of direct kinetic effects into turbulent flame computations for practical problems. In the present paper reduced seven step, five step and four step reaction mechanisms for ammonia oxidation have been developed by the study ofpremixed laminar flames. A systematic reduction technique using steady state assumptions for intermediaries and radicals has been used to obtain the reduced schemes from a comprehensive detailed kinetic mechanism. Special emphasis has been given to the formation and destruction of NO and N2O The reduced mechanisms have been tested by comparing calculations performed with the reduced mechanisms and the detailed starting mechanism. Results for an extensive set of flat laminar premixed H2/O2 flames doped with ammonia or ammonia and nitric oxide diluted with argon and NH3/O2 flames are presented. The reduced mechanisms generally provide excellent agreement with the temperature, major species and nitric-oxide profiles for all flame conditions covered in the present study. However, the 4-step mechanism is not recommended for calculations where accurate N2O profiles arc required, as the steady state approximation for N2O is not well founded.