In situ species diagnostics and kinetic study of plasma activated ethylene dissociation and oxidation in a low temperature flow reactor
In situ species diagnostics and kinetic study of plasma activated ethylene dissociation and oxidation in a low temperature flow reactor
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DOI：
10.1016/j.proci.2014.08.001
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发表时间：
2015
影响因子：
9.4
通讯作者：
J. Lefkowitz;M. Uddi;B. Windom;G. Lou;Y. Ju
中科院分区：
文献类型：
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作者：
J. Lefkowitz;M. Uddi;B. Windom;G. Lou;Y. Ju
在低温流动反应器（低于500 K）中，采用中红外激光吸收光谱法，对纳秒重复脉冲等离子体激活的C_2H_4/Ar解离和C_2H_4/O_2/Ar氧化过程进行了原位测量，测量压力为60 Torr，脉冲放电模式为连续放电模式和脉冲放电模式，脉冲数为150。在连续放电模式下，通过气相色谱法验证和补充原位诊断的测量结果。组装了一个新近发展起来的等离子体活化C2 H4氧化反应动力学机理（HP-Mech-Plasma）。等离子体活化解离实验表明，电子直接碰撞解离生成乙炔和激发电离氩碰撞反应解离生成乙炔是等离子体活化解离的主要燃料消耗途径。等离子体活化C2 H4氧化实验表明，存在三种燃料消耗途径：（1）通过O2加成反应的等离子体活化低温燃料氧化途径;（2）通过电子、离子和电子激发分子碰撞解离的直接裂解途径;（3）通过等离子体产生的自由基的直接氧化途径。结果发现，等离子体活化的低温氧化途径是占主导地位的，并导致大量的甲醛形成与较少的乙炔和可忽略不计的大烃分子相比，解离实验。结果还表明，后两种燃料消耗途径强烈依赖于O2和Ar浓度，由于它们的原子氧和激发Ar的产生的影响。虽然目前的模型提高了整体预测USC-Mech II等离子体活化解离和氧化，这两种模型都未能定量预测H2O和CH 4的形成。目前的数据提供了很好的目标，为未来的模型开发等离子体辅助燃烧。
In situmeasurements by mid-IR laser absorption spectroscopy of C2H4/Ar dissociation and C2H4/O2/Ar oxidation activated by a nanosecond repetitively pulsed plasma have been conducted in a low temperature flow reactor (below 500 K) at a pressure of 60 Torr for both a continuously pulsed plasma discharge mode and a burst mode with 150 pulses. The measurements of thein situdiagnostics are validated and complemented by gas chromatography in the continuous discharge mode. A recently developed kinetic mechanism (HP-Mech-Plasma) for plasma activated C2H4oxidation is assembled. The experiments of plasma activated dissociation show that the formation of acetylene by direct electron impact dissociation and dissociation by excited and ionized argon collision reactions is the major fuel consumption pathway. Plasma activated C2H4oxidation experiments show that there exist three fuel consumption pathways, (1) a plasma activated low temperature fuel oxidation pathway via O2addition reactions; (2) a direct fragmentation pathway via collisional dissociation by electrons, ions, and electronically excited molecules; and (3) a direct oxidation pathway by plasma generated radicals. It is found that the plasma activated low temperature oxidation pathway is dominant and leads to a large amount of formaldehyde formation with less acetylene and negligible large hydrocarbon molecules as compared to the dissociation experiment. The results also indicate that the latter two fuel consumption pathways are strongly dependent on O2and Ar concentrations due to their effect on the production of atomic oxygen and excited Ar. Although the current model improves the overall prediction over USC-Mech II for plasma activated dissociation and oxidation, both models fail to predict quantitatively the H2O and CH4formation. The present data provide good targets for future model development in plasma-assisted combustion.