OH* chemiluminescence in the H2NO2 and H2N2O systems
OH* chemiluminescence in the H2NO2 and H2N2O systems
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DOI：
10.1016/j.combustflame.2019.11.010
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发表时间：
2020-03
影响因子：
4.4
通讯作者：
C. Mulvihill;E. Petersen
中科院分区：
文献类型：
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作者：
C. Mulvihill;E. Petersen
激波管实验在1535和2003 K之间、接近1.1 atm的0.222% H 2/0.392% NO 2/Ar的混合物中进行。当仅包括 OH* 形成反应 N 2 O+ H⇆ N 2+ OH*(R2) 和 O+ H (+ M)⇆ OH*(+ M)(R3) 时，记录了 307 nm 附近 A→ X 波段 OH* 化学发光的时程，结果与最近的碳氢化合物/NO x 模型的预测表现出较差的一致性。由于化学发光与放热密切相关，并且已知反应NO 2+ H⇆ NO+ OH是H 2 单键NO 2 氧化过程中放热的主要原因，因此首次提出了化学发光反应NO 2+ H⇆ NO+ OH*(R1)。通过拟合实验 OH* 数据，获得最佳拟合速率常数为 k 1= 7.0× 10 13 exp (− 27, 680/T)，k 1 单位为 cm 3 mol− 1 s− 1，T 单位为 K。k 1 的该表达式在 1535 至 2003 K 的实验温度范围内有效。拟合的 k 1 值取决于所使用的基本 NOx 机制。还在 1448 至 1776 K 之间、接近 1.1 atm 的 0.333% H 2/0.666% N 2 O/Ar 混合物中获得了 OH* 分布。将新反应R1引入机理中对新获得的H 2 单键N 2 O OH*数据或之前文献中的H 2 单键N 2 O OH*数据的建模没有影响。最后，R1 和 R2 违反了长期以来关于此类反应放热性的假设，这表明在未来的研究中可以放宽用于评估潜在化学发光反应的放热性标准。相反，可以采用基于反应焓和反应熵的新方法来识别新的化学发光反应。据作者所知，这是对 H 2 单键NO 2 系统中 OH* 化学发光动力学的首次详细研究。
Shock-tube experiments were performed in a mixture of 0.222% H 2/0.392% NO 2/Ar between 1535 and 2003 K near 1.1 atm. Time histories of OH* chemiluminescence from the A→ X band near 307 nm were recorded and showed poor agreement with predictions from a recent hydrocarbon/NO x model when only the OH*-forming reactions N 2 O+ H⇆ N 2+ OH*(R2) and O+ H (+ M)⇆ OH*(+ M)(R3) were included. Since chemiluminescence is strongly correlated with heat release and since the reaction NO 2+ H⇆ NO+ OH is known to be primarily responsible for heat release during H 2 single bondNO 2 oxidation, the chemiluminescent reaction NO 2+ H⇆ NO+ OH*(R1) was proposed for the first time. By fitting the experimental OH* data, a best-fit rate constant was obtained as k 1= 7.0× 10 13 exp (− 27, 680/T), with k 1 in cm 3 mol− 1 s− 1 and T in K. This expression for k 1 is valid in the experimental temperature range of 1535 to 2003 K. The fitted k 1 value is dependent on the base NOx mechanism used. OH* profiles were also acquired in a mixture of 0.333% H 2/0.666% N 2 O/Ar between 1448 and 1776 K near 1.1 atm. The introduction of the new reaction R1 into the mechanism had no effect on the modeling of either the newly acquired H 2 single bondN 2 O OH* data or previous H 2 single bondN 2 O OH* data from the literature. Finally, R1 and R2 violate a long-held assumption concerning the exothermicity of such reactions, suggesting that the exothermicity criteria used to evaluate potential chemiluminescent reactions could be relaxed in future studies. Instead, a new methodology based on both the enthalpy of reaction and the entropy of reaction could be employed to identify new chemiluminescent reactions. To the best of the authors’ knowledge, this is the first detailed study of OH* chemiluminescence kinetics in the H 2 single bondNO 2 system.