Ignition Delay Time and Chemical Kinetic Study of Methane and Nitrous Oxide Mixtures at High Temperatures

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• 作者：Fuquan Deng ; Feiyu Yang ; Peng Zhang ; Youshun Pan ; Yingjia Zhang ; Zuohua Huang
• 刊名：Energy & Fuels
• 出版年：2016
• 出版时间：February 18, 2016
• 年：2016
• 卷：30
• 期：2
• 页码：1415-1427
• 全文大小：1091K
• ISSN：1520-5029

文摘

Ignition delay times of N₂O/CH₄/O₂/Ar mixtures with varying N₂O mixing ratios (N₂O/CH₄ mole blending ratio = 0:100, 30:70, 50:50, and 70:30) were measured behind reflected shock waves at pressures of 1.2–16 atm, equivalence ratios of 0.5–2.0, and temperatures of 1220–2336 K. At currently investigated conditions, the reactivity of methane is significantly promoted by N₂O addition, resulting in an obvious reduction of the ignition delay time, and this effect becomes more pronounced at the fuel-rich condition and high pressure. However, N₂O addition only results in a slight reduction in the global activation energy. To eliminate the effect of different hydrocarbon mechanisms, a widely accepted kinetic mechanism, Aramco Mech 1.3, is used to combine with three available NO_x submodels (Gersen et al., Konnov, and Mathieu et al.) and simulate the measured ignition delay times. Generally, the three assembled models give a similar prediction performance and agree well with the experimental data for a low level of N₂O addition, but they exhibit a discrepancy for a high level of N₂O addition. Sensitivity analysis and radical pool analysis are conducted to interpret the kinetic effect of N₂O addition on methane ignition chemistry. Results indicate that the promoting effect of N₂O addition on methane ignition is mainly attributed to the contribution of the following three reactions: N₂O + M = N₂ + O^• • + M, N₂O + H^• = N₂ + ^•OH, and N₂O + ^•CH₃ = CH₃O^• + N₂, which can significantly increase the concentration of the radical pool and accelerate the peak of the radical pool.