Ignition delay times (IDTs) were measured in a shock tube facility for NH/n-heptane mixtures with NH concentrations in the blending fuel ranging from 0.3 to 0.95 by molar fraction. The measurements were conducted under low pressure of 2 atm and intermediate temperatures of 1350–1500 K at equivalence ratios of 0.5, 1, and 2. With the increase of n-heptane content or equivalence ratio, there is a decrease in the IDTs of NH/n-heptane mixtures at intermediate temperatures. A detailed mechanism was updated in this study based on the mechanism of Dong et al. Subsequently, the proposed mechanism was compared to existing blending mechanisms of ammonia and n-heptane in terms of laminar burning velocities (LBVs), IDTs, and species profiles reported in literature. The present model improved the predictions in reproducing the performed experimental measurements compared to previous mechanisms. Finally, rate of production (ROP), sensitivity analysis, and instantaneous and cumulative reaction path analysis were performed to interpret the experiment observations and deepen the understanding of auto-ignition kinetics of ammonia and n-heptane. The results indicate that intermediate species, such as CH and CH, characterized by long lifespans and high concentrations during n-heptane decomposition, play a crucial role at elevated temperatures, while the significance of n-heptane dehydrogenation by NH diminishes with increasing temperature.

中文翻译：

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氨/正庚烷混合物中温自燃实验及动力学模型研究

在激波管设备中测量了 NH/正庚烷混合物的点火延迟时间 (IDT)，混合燃料中 NH 浓度的摩尔分数范围为 0.3 至 0.95。测量在 2 atm 低压和 1350-1500 K 中温下进行，当量比分别为 0.5、1 和 2。随着正庚烷含量或当量比的增加，NH 的 IDT 降低中间温度下的正庚烷混合物。本研究在Dong等人的机制的基础上更新了详细的机制。随后，将所提出的机制与现有的氨和正庚烷混合机制在层流燃烧速度（LBV）、IDT和文献中报道的物种概况方面进行了比较。与以前的机制相比，本模型改进了再现所进行的实验测量的预测。最后，进行产率（ROP）、灵敏度分析以及瞬时和累积反应路径分析来解释实验观察结果并加深对氨和正庚烷自燃动力学的理解。结果表明，在正庚烷分解过程中，中间体，如CH和CH，具有长寿命和高浓度的特点，在高温下发挥着至关重要的作用，而NH对正庚烷脱氢的重要性随着温度的升高而减弱。