Measurement of methane autoignition delays in carbon dioxide and argon diluents at high pressure conditions
Measurement of methane autoignition delays in carbon dioxide and argon diluents at high pressure conditions
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DOI：
10.1016/j.combustflame.2019.03.020
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发表时间：
2019-06
影响因子：
4.4
通讯作者：
M. Karimi;Bradley A. Ochs;Zefang Liu;Devesh Ranjan;Wenting Sun
中科院分区：
文献类型：
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作者：
M. Karimi;Bradley A. Ochs;Zefang Liu;Devesh Ranjan;Wenting Sun
直燃式超临界二氧化碳 (sCO2) 动力循环效率高，同时几乎可以完全捕获二氧化碳 (CO2)。 sCO2动力循环（100-300bar）燃烧室的运行条件与传统燃气轮机燃烧室有很大不同。然而，在这些条件下，诸如自燃延迟等燃烧特性尚不清楚。本研究报告了使用高压激波管在 100 和 200 bar 以及 1139-1433K 温度范围内稀释二氧化碳环境下的甲烷自燃延迟测量。为了研究 CO2 对点火的影响，通过用氩气代替二氧化碳，在 100 和 200bar 下进行了类似的实验。然后将实验数据与使用不同化学动力学模型的计算进行比较。对于本研究的条件，Aramco Mech 2.0 的预测总体上与实验测量结果吻合得最好，而 GRI 3.0 动力学模型的预测与实验的偏差最大（3 倍）。灵敏度和反应途径分析表明，甲基 (CH3) 重组形成乙烷 (C2H6) 和 CH3 氧化形成甲醇盐 (CH3O) 是控制温度高于约 1250K 时点火行为的最重要反应。然而，在温度低于约 1250K 时，发现了甲基自由基的额外反应途径，通过 CH3+O2+M = CH3O2+M 形成甲基二氧己基(CH3O2)。该反应途径在指示较低温度条件下的点火趋势方面发挥着独特的作用。
The directly fired supercritical carbon dioxide (sCO2) power cycle has high efficiency while allowing nearly complete carbon dioxide (CO2) capture. The operating conditions of sCO2power cycle (100–300 bar) combustors are dramatically different from conventional gas turbine combustors. However, combustion properties such as autoignition delay are not well understood at these conditions. This study reports methane autoignition delay measurements for diluted carbon dioxide environments at 100 and 200 bar and at temperatures within the range of 1139–1433 K using a high pressure shock tube. To study the effect of CO2on ignition, similar experiments are conducted at 100 and 200 bar by replacing carbon dioxide with argon. The experimental data is then compared with calculations using different chemical kinetics models. For the conditions of this study, predictions of the Aramco Mech 2.0 show the overall best agreement with experimental measurements, while predictions of the GRI 3.0 kinetic model have the largest (by a factor of 3) deviation with experiments. Sensitivity and reaction pathway analyses reveal that methyl (CH3) recombination to form ethane (C2H6) and oxidation of CH3to form methoxide (CH3O) are the most important reactions controlling the ignition behavior at temperatures greater than approximately 1250 K. However, at temperatures below approximately 1250 K, an additional reaction pathway for methyl radicals is found through CH3+O2+M = CH3O2+M which leads to formation of methyldioxidanyl (CH3O2). This reaction pathway plays a distinct role in dictating the ignition trends at lower temperature conditions.