Kinetics of plasma assisted pyrolysis and oxidation of ethylene. Part 2: Kinetic modeling studies
Kinetics of plasma assisted pyrolysis and oxidation of ethylene. Part 2: Kinetic modeling studies
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DOI：
10.1016/j.combustflame.2016.10.023
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发表时间：
2017-02
影响因子：
4.4
通讯作者：
N. Tsolas;R. Yetter;I. Adamovich
中科院分区：
文献类型：
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作者：
N. Tsolas;R. Yetter;I. Adamovich
对等离子体辅助下乙烯裂解和氧化反应动力学进行了数值模拟研究。将等离子体化学过程（包括电子碰撞反应和电子激发态反应）与综合燃烧机理相结合，建立了等离子体辅助乙烯热解氧化反应的动力学机理。为了测试所构建的机制的准确性，数值计算结果进行了比较，在等离子体流反应器中获得的实验数据，在高度稀释的条件下，在氩气中，在1个大气压的压力，温度范围从520 K至1250 K。等离子体辅助热解结果的比较表明，模型和实验之间的差异不大。电子激发的氩气的直接碰撞淬火乙烯是负责低温等离子体辅助热解实验中看到的燃料消耗的增强。烃自由基通常经历加成和重组反应以产生几种C3和C4烃中间体。随着温度的升高，等离子体效应减弱，反应被热解取代。等离子体辅助氧化乙烯的实验和模拟结果的比较表明，相对较好的协议，大多数主要和次要物种。然而，当T < 750 K时，乙烯和乙醛的一致性较差.在氧化系统中，O2对激发态氩的碰撞猝灭产生了O原子自由基池，补充了等离子体特有的燃料解离反应。发现等离子体在不同温度下对氧化动力学有不同的影响。在低温下，R+ O2型化学反应（R是烃基）促进含氧物质的形成，以增强甲醛的氧化作用。在中间温度下，烃和醇中间体的形成相对于低温减慢了氧化过程。最后，在高温下，等离子体化学反应不能与主导和控制整个氧化过程的中性化学的高温支链反应竞争。
The kinetics of plasma-assisted pyrolysis and oxidation of ethylene have been numerically investigated. Combining plasma chemistry processes including electron-impact reactions, and reactions of electronically excited species with a comprehensive combustion mechanism, a plasma-assisted kinetic mechanism of ethylene pyrolysis and oxidation has been constructed. To test the accuracy of the constructed mechanism, numerical results were compared to experimental data obtained in a plasma flow reactor, performed under highly diluted conditions in argon at a pressure of 1 atm for temperatures ranging from 520 K to 1250 K. Comparison of plasma-assisted pyrolysis results indicates little discrepancy between the model and experiments. Direct collisional quenching of electronically excited argon by ethylene is responsible for the low temperature enhancement of fuel consumption seen in the plasma-assisted pyrolysis experiments. Hydrocarbon radicals generally undergo addition and recombination reactions to yield several C3and C4hydrocarbon intermediates. As temperature increases, the plasma effects diminish and the reaction is overtaken by thermal pyrolysis. Comparison of experimental and modeling results for plasma-assisted oxidation of ethylene demonstrated relatively good agreement for most major and minor species. However, poor agreement was found for ethylene and acetaldehyde forT< 750 K. In the oxidation system, collisional quenching of excited argon by O2to generate the O-atom radical pool complemented the plasma-specific fuel dissociation reactions. The plasma was found to have different effects on the oxidation kinetics at different temperatures. At low temperatures, R+O2type chemistry (R being a hydrocarbon radical) facilitates the formation of oxygenated species to enhance oxidation by way of formaldehyde. At intermediate temperatures, the formation of hydrocarbon and alcohol intermediates slows the oxidation process relative to the low temperatures. Finally, at high temperatures, plasma chemical reactions are unable to compete against the high temperature chain-branching reactions of the neutral chemistry that dominate and control the overall oxidation process.