Ammonia (NH₃) is a promising carbon-free fuel and a hydrogen carrier. In recent years, there has been a large number of experimental and numerical studies to understand the chemical kinetics of NH₃ in moderate to extremely complex systems. This study focused on understanding the chemical kinetics of NH₃ in a simple system (pyrolysis). Shock-tube experiments were performed to monitor the NH₃ time history profiles during pyrolysis, with and without the presence of H₂, using a new laser absorption diagnostic near 10.4 µm. The pyrolysis experiments were conducted for mixtures of ∼ 0.5% NH₃/Ar and ∼ 0.42% NH₃/2% H₂/Ar behind reflected shock waves, near atmospheric pressure, and over a temperature range of 2100–3000 K. Using the data from the present study as a guide, along with NH₃ pyrolysis data from the literature, a detailed chemical kinetics mechanism for NH₃ pyrolysis is proposed herein. This mechanism was assembled using available reaction rate constants from the literature. The mechanism showed excellent agreement with the experimental results, as well as with the literature data. Additionally, an assessment of 15 detailed NH₃ chemical kinetics mechanisms on their capabilities of predicting the new pyrolysis experiments was performed. The assessment showed that these literature mechanisms yield significantly different predictions, with only one model producing acceptable results for the majority of the NH₃ pyrolysis experiments. The effect of pyrolysis reactions on the prediction of oxidation data was investigated by updating the pyrolysis sub-mechanism of selected literature models with the reactions of the present pyrolysis model. The prediction of the updated literature models significantly improved for ignition delay time and flame speed literature data, indicating the importance of pyrolysis reactions for high-temperature oxidation chemistry.

氨（NH ₃）是一种很有前途的无碳燃料和氢载体。近年来，已经有大量的实验和数值研究来了解 NH ₃在中等至极其复杂的系统中的化学动力学。本研究的重点是了解简单系统（热解）中 NH ₃的化学动力学。执行冲击管实验以监测热解过程中的 NH ₃时间历程曲线，无论是否存在 H ₂，使用接近 10.4 µm 的新激光吸收诊断。热解实验是针对约 0.5% NH ₃ /Ar 和约 0.42% NH ₃ /2% H _{2 的}混合物进行的/Ar 位于反射冲击波之后，接近大气压，温度范围为 2100–3000 K。使用本研究的数据作为指导，以及文献中的NH ₃热解数据，NH的详细化学动力学机制₃热解是本文提出的。该机制是使用文献中可用的反应速率常数组装的。该机制与实验结果以及文献数据显示出极好的一致性。此外，对 15 个详细的 NH ₃对其预测新热解实验的能力进行了化学动力学机制研究。评估表明，这些文献机制产生了显着不同的预测，对于大多数 NH ₃热解实验，只有一种模型产生可接受的结果。通过用当前热解模型的反应更新所选文献模型的热解子机制，研究了热解反应对氧化数据预测的影响。更新文献模型的预测显着改善了点火延迟时间和火焰速度文献数据，表明热解反应对高温氧化化学的重要性。