Nitric Oxide Emissions from Laminar Diffusion Flames: Effects of Air-Side versus Fuel-Side Diluent Addition

摘要: Abstract Flue gas recirculation (FGR) is a well-known method used to control oxides of nitrogen (NO x ) in industrial burner applications. Recent small- and large-scale experiments have shown that introducing the recirculated flue gases with fuel results much greater reduction NO , per unit mass recirculated, compared combustion air. At present, however, there no definitive understanding why more effective than conventional FGR. The objective present investigation ascertain what degree chemical kinetics and/or molecular transport effects can explain differences observed between fuel-side air-side introduction by studying laminar diffusion flames. Numerical simulations counterflow flames using full were performed emission indices calculated for various conditions. Studies conducted which N 2 diluent was added either on fuel- or flame conditions fixed initial velocities flux. Results from these simulation studies indicate major factor effectiveness differential effect zone residence times associated versus dilution. Experiments jet air stream diluted . showed dilution somewhat higher temperatures measured appear be principal cause emissions. both numerical suggest that, although kinetic phenomena are affected location addition depending flow conditions, dramatically over practical applications likely also turbulent mixing heat transfer.