Multi-speciation in shock-heated H2−N2OO2 mixtures: Investigation on N2O reduction

Mitigating greenhouse gas emissions and addressing safety concerns in combustion systems are critical for advancing sustainable energy technologies. Using state-of-the-art multi-species laser absorption techniques, we conducted a comprehensive experimental investigation of the chemical interactions between nitrous oxide (N₂O) and hydrogen (H₂) with and without oxygen (O₂) behind reflected shock waves. Speciation time-histories of N₂O, NO, H₂O, and OH, as well as ignition delay times, were measured over a temperature range of 890–1936 K and pressures of 1.16–2.19 bar. These measurements offer a comprehensive understanding of reactants, major pollutants, radicals, and final products for N₂OH₂−O₂ system. Our proposed chemical kinetic model, featuring an updated N₂OH₂ subset, provides enhanced predictability and highlights the interaction chemistry involving N₂O and H₂. In contrast, literature models exhibit significant discrepancies, particularly in predicting NO profiles and ignition delay times below 940 K. The experimental data and kinetic analysis reveal distinct reaction regimes characterized by the interplay of radical species (e.g., OH, O and NH) and highlights the pivotal role of N₂OH₂ interaction chemistry in influencing ignition and reaction dynamics. The hydrogen oxidation chemistry under oxidizer-tailored conditions reveals distinct temperature-dependent behavior. Above 1100 K, ignition is promoted by both the N₂O + H reactions and the thermal decomposition of N₂O. In contrast, within the 850–1000 K range, the recombination of N₂O with H atoms to form HNNO slightly suppresses ignition. By bridging critical knowledge gaps, the findings advance both the fundamental understanding of N₂OH₂ systems and the development of sustainable energy strategies.