Plasma-assisted Ammonia Combustion: The Effect of Equivalence Ratio on NO Emissions

As a carbon-free fuel and hydrogen carrier, ammonia has gained increasing attention in the combustion community to support the global decarbonisation efforts. However, it has unfavorable flame properties and emissions characteristics such as low flammability and intrinsic trade-off between nitric oxide emissions and slip ammonia that hinders its widespread integration to the heat and power sectors. As a promising technology, non-thermal plasma has already presented the potential to assist swirling ammonia flames with significant improvements in NOX abatement and flammability, while eliminating the need for blending with other reactive fuels such as hydrogen and methane. For this study, a plasma burner was designed to explore plasma discharge interaction with a highly swirling premixed ammonia flame over a range of equivalence ratios, and its effect on NO emissions. The results revealed that average plasma power varied with the equivalence ratio and the reduced electric field affected the NO emissions characteristics of premixed ammonia flames.