N2O reduction with selective excitation of species by non-equilibrium plasma in an NH3/air mixture

Non-equilibrium plasma can enhance NH 3 combustion and simultaneously decrease N 2 O/NO x emissions at low temperatures. This study proposes a method of selective excitation of specific species in an NH 3 /air mixture, such as O 2 , N 2 , air, or NH 3 , to assess the effects for decreasing N 2 O concentrations in the non-equilibrium plasma-assisted NH 3 oxidation via numerical modeling . The selective excitation is realized by removing the electron impact reactions and chemical reactions involving excited species apart from the target species. The results demonstrate that the selective excitation of specific species can significantly reduce N 2 O concentrations compared with plasma-excited NH 3 /air mixtures at low temperatures. Specifically, the optimal N 2 O emission reduction at 800 K is achieved with plasma excitation of O 2 . Due to the absence of interactions between NH 3 and electron/electronically excited state species N 2 * and N( 2 D), the concentrations of NH/NH 2 radicals contributing to N 2 O production dramatically decrease. Meanwhile, the primary N 2 O consumption pathway becomes more prominent due to the efficient production of O( 1 D). The reaction rate of the main N 2 O production pathway is 1–2 orders of magnitude lower than that of the NH 3 /air mixture. This work offers valuable insight and guidance for combustor design in advanced engines to effectively reduce N 2 O emissions by using non-equilibrium plasma.