Kinetic effects of non-equilibrium plasma-assisted methane oxidation on diffusion flame extinction limits
Kinetic effects of non-equilibrium plasma-assisted methane oxidation on diffusion flame extinction limits
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DOI：
10.1016/j.combustflame.2011.07.008
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发表时间：
2012
影响因子：
4.4
通讯作者：
Wenting Sun;M. Uddi;S. Won;T. Ombrello;C. Carter;Y. Ju
中科院分区：
文献类型：
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作者：
Wenting Sun;M. Uddi;S. Won;T. Ombrello;C. Carter;Y. Ju
研究了低温非平衡等离子体辅助ch4氧化在60Torr条件下对部分预混甲烷火焰熄灭的动力学影响。实验表明，非平衡等离子体能显著加速低温下的ch4氧化。等离子体辅助燃烧的ch4快速氧化导致化学热释放速度快，消光极限明显延长。此外，实验结果表明，氧化剂流中的部分燃料混合导致氧浓度急剧下降，因为它在低温下被ch4氧化迅速消耗。采用双光子吸收激光诱导荧光（TALIF）法（用于原子氧）、傅里叶变换红外光谱（FTIR）和气相色谱（GC）对等离子体辅助ch4氧化产物进行了测量。利用产物浓度对等离子体辅助燃烧动力学模型进行了验证。结果表明，动力学模型对CO、H2O和h2浓度的预测过高，对co2浓度的预测过低。通径通量分析表明，等离子体产生的O是消光增强的关键物质。此外，结果表明，O主要通过直接电子冲击离解反应和电子激发分子与O2的碰撞离解反应产生。此外，这些涉及电子冲击和ch4激发态碰撞解离的反应贡献了大约0.1摩尔分数的总自由基生成。本实验获得了低温等离子体辅助燃烧的定量物种和消光数据，以约束等离子体/火焰动力学模型的不确定性。
The kinetic effects of low temperature non-equilibrium plasma assisted CH4oxidation on the extinction of partially premixed methane flames was studied at 60Torr by blending 2% CH4by volume into the oxidizer stream of a counterflow system. The experiments showed that non-equilibrium plasma can dramatically accelerate the CH4oxidation at low temperature. The rapid CH4oxidation via plasma assisted combustion resulted in fast chemical heat release and extended the extinction limits significantly. Furthermore, experimental results showed that partial fuel mixing in the oxidizer stream led to a dramatic decrease of O concentration due to its rapid consumption by CH4oxidation at low temperature. The products of plasma assisted CH4oxidation were measured using the Two-photon Absorption Laser-Induced Fluorescence (TALIF) method (for atomic oxygen, O), Fourier Transform Infrared (FTIR) spectroscopy, and Gas Chromatography (GC). The product concentrations were used to validate the plasma assisted combustion kinetic model. The comparisons showed the kinetic model over-predicted the CO, H2O and H2concentrations and under-predicted CO2concentration. A path flux analysis showed that O generated by the plasma was the critical species for extinction enhancement. In addition, the results showed that O was produced mainly by direct electron impact dissociation reactions and the collisional dissociation reactions of electronically excited molecules with O2. Moreover, these reactions involving electron impact and excited species collisional dissociation of CH4contributed approximately a mole fraction of 0.1 of total radical production. The present experiments produced quantitative species and extinction data of low temperature plasma assisted combustion to constrain the uncertainties in plasma/flame kinetic models.