Suppression of NOx emissions by intensive strain in lean premixed hydrogen flamelets
Suppression of NOx emissions by intensive strain in lean premixed hydrogen flamelets
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DOI：
10.1016/j.ijhydene.2023.08.110
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发表时间：
2023-09
影响因子：
7.2
通讯作者：
Alessandro Porcarelli;B. Kruljević;I. Langella
中科院分区：
文献类型：
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作者：
Alessandro Porcarelli;B. Kruljević;I. Langella
在贫氧条件下，研究了预混、高应变、纯氢空气火炬中NOx的生成。对具有不同应变率的反应物-产物构型进行了详细的化学、一维和二维模拟。结果首次强调，对于稀薄纯氢火炬，NOx排放随着应变率的增加而受到抑制。通过热NOx生成途径观察到的降幅最大。在这里，NOx的抑制是由途径反应中涉及的自由基在火焰面上的重新分布触发的。进一步与甲烷火焰进行了比较，以了解所观察到的应变趋势在多大程度上可以与氢燃烧特征具体联系起来。在压力增加和当量比不同的情况下，也观察到了与应变类似的NOx抑制趋势，尽管下降的速度不同。基于观测结果和进一步的理论考虑，提出了一个关联式，以根据施加的应变率和当量比来预测NOx排放。
NOxformation in premixed, highly-strained, pure hydrogen-air flamelets is investigated at lean conditions. Detailed-chemistry, one-dimensional and two-dimensional simulations are performed on a reactants-to-products configuration with varying applied strain rate. The results highlight for the first time for lean pure-hydrogen flamelets that NOxemissions are suppressed as strain rate is increased. The most substantial decrease is observed across the thermal NOxformation pathway. Here the suppression of NOxis triggered by a redistribution across the flamelet of the radicals involved in the pathway reactions. A comparison with methane flamelets is further performed to understand to what extent the observed trends with strain can be specifically linked to hydrogen burning features. Similar NOxsuppression trends with strain are also observed for increased pressure and different equivalence ratios, although with different rates of decrease. A correlation is proposed based on the observed results and further theoretical considerations, to predict NOxemissions according to applied strain rate and equivalence ratio.