The Role of Energy-Releasing Kinetics in NOxFormation: Fuel-Lean, Jet-Stirred CO-Air Combustion

Abstract

Oxides of nitrogen concentrations, temperatures and mass flow rates near reactor blowout have been measured for chemically rate-limited, fuel-lean combustion of carbon monoxide with moist air in a jet-stirred reactor at 0.5 and 1 atmosphere. Comparisons with predictions obtained by modeling the jet-stirred reactor as a micromixed perfectly stirred reactor are used to examine the detailed influences of energy-releasing kinetic processes on NO_x formation. Reaction radical intermediates and, in particular, oxygen atoms are shown to play a key role in this influence. For fuel-lean combustion, under conditions of intense turbulence and backmixing, super-equilibrium concentrations of oxygen atoms cause N₂ O to act as an important intermediate leading to NO_x formation. Measurements indicating the influence of finite mixing on experimental reactor performance and NO_x emissions are presented as well.