N₂O Consumption by Thermal Decomposition and Reduction with CH₄, C₂H₆ and NH₃

Consumption of nitrous oxide (N₂O) by thermal decomposition and reduction with methane (CH₄), ethane (C₂H₆), and ammonia (NH₃) were investigated using a micro-flow reactor with controlled temperature profile. N₂O mole fractions were measured using a gas chromatograph and mass spectrometers at the maximum wall temperatures from 900 to 1400 K. For N₂O thermal decomposition, the measured N₂O mole fraction was in good agreement with the prediction using the model proposed by Mulvihill, et al. The low-pressure limit of N₂O (+M) = N₂ + O (+M) was dominant and H₂O showed the largest impact on N₂O consumption as a third-body, followed by CO₂ and Ar. New third-body coefficients were proposed from the comparison of measured N₂O mole fractions with model predictions. For N₂O reduction with respective fuels, experiments showed that N₂O consumption became greater in the order of C₂H₆/N₂O/Ar ≈ NH₃/N₂O/Ar > CH₄/N₂O/Ar > N₂O/Ar mixtures. Chemical reaction analyses showed that N₂O + H = N₂ + OH is the dominant reaction for N₂O consumption in all fuel/N₂O cases. In the C₂H₆/N₂O case, high rates of H radical production from the fuel radical (C₂H₅) at a low temperature was identified, resulting in a greater N₂O consumption than the CH₄/N₂O case. In the NH₃/N₂O case, a reaction of N₂O and the fuel radical (NH₂) showed high contribution to N₂O consumption. Additionally, NNH and H₂, the products in N₂H₂ + H = NNH + H₂, produce H radicals through subsequent reactions. These reactions create a cycle of production/consumption of H and OH radicals and promote consumption of NH₃ and N₂O.