NH3 oxidation by NO2 in a jet-stirred reactor: The effect of significant uncertainties in H2NO kinetics
NH3 oxidation by NO2 in a jet-stirred reactor: The effect of significant uncertainties in H2NO kinetics
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DOI：
10.1016/j.jaecs.2022.100095
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发表时间：
2022-11
影响因子：
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通讯作者：
Rodger E. Cornell;M. Barbet;Joe Lee;M. P. Burke
中科院分区：
文献类型：
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作者：
Rodger E. Cornell;M. Barbet;Joe Lee;M. P. Burke
了解氨(NH3)的动力学对于越来越多的应用正变得越来越重要--从它作为NOx还原剂的作用，到生物质和含能材料(特别是绿色推进剂)燃烧过程中的关键中间体，以及潜在的无碳能源载体和存储介质。这种广泛的应用需要全面的NH3动力学模型，在广泛的温度、压力和混合物范围内都是可靠的。然而，许多人仍然认为目前对其动力学的理解是不完整的。例如，很少有关于含氮物种氧化NH3的实验研究，这些研究提供了探索相对未经测试的反应(或其组合)的机会，以便能够更全面地了解NH3动力学。为了弥补这一差距，我们在中温范围(700-1100K)进行了NO2氧化NH3的喷射搅拌反应器实验。用气相色谱、化学发光和红外吸收相结合的方法测定了NH3、NO2、NO和O2的摩尔分数。不同诊断方法之间的一致性(NH3的≤为4%，NO2的≤为7%)和出色的实验重复性确保了对所有物种测量的高度置信度。物种测量与模型预测的比较表明，最近的动力学模型存在缺陷，特别是在高温(≥900K)下NH3消耗和NO生成的问题。不确定度加权动力学分析指出了生成(NH2+NO2)和消耗(H2 NO+NO2，H2 NO+OH)H2 NO的反应的重要性，这两个反应在本体系(以及许多其他NH3氧化体系)中都是不确定和有影响的。这些反应和本数据集中强调的其他反应也是NH3/空气着火和N2O形成的关键反应，这两个反应仍然是发动机NH3燃烧的突出挑战。因此，解决在本数据集观察到的建模缺陷对于能够使用NH3作为燃料的预测模型显得尤为重要。
Understanding the kinetics of ammonia (NH 3) is becoming increasingly important to a growing variety of applications—ranging from its role as a NO x reduction agent, a key intermediate during combustion of biomass and energetic materials (especially green propellants), and a potential carbon-free energy carrier and storage medium. This wide variety of applications calls for comprehensive NH 3 kinetic models that are reliable over wide ranges of temperatures, pressures, and mixtures. Yet, many still consider the present understanding of its kinetics to be incomplete. For example, there are few experimental studies of NH 3 oxidation by nitrogen-containing species, which offer the opportunity to probe relatively untested reactions (or combinations thereof) to enable a more comprehensive understanding of NH 3 kinetics. To address this gap, we perform jet-stirred reactor experiments of NH 3 oxidation by NO 2 over an intermediate temperature range (700–1100 K). The mole fractions of NH 3, NO 2, NO, and O 2 are measured through a combination of gas chromatography, chemiluminescence, and infrared absorption. Agreement among different diagnostics (≤ 4% for NH 3 and≤ 7% for NO 2) and excellent experimental repeatability ensure high confidence in all species measurements. Comparisons of species measurements to model predictions revealed deficiencies in recent kinetic models, particularly for NH 3 consumption and NO formation at elevated temperatures (≥ 900 K). Uncertainty-weighted kinetic analyses point to the importance of reactions that form (NH2+ NO 2) and consume (H 2 NO+ NO 2, H 2 NO+ OH) H 2 NO, both of which are uncertain and influential in this system (and many other NH 3 oxidation systems). These and other reactions accentuated in the present dataset are also key reactions in NH 3/air ignition and N 2 O formation, both of which remain outstanding challenges for NH 3 combustion in engines. Consequently, resolving the modeling deficiencies observed for the present dataset appears especially important to predictive models to enable the use of NH 3 as a fuel.