Measurements of Positively Charged Ions in Premixed Methane-Oxygen Atmospheric Flames
Measurements of Positively Charged Ions in Premixed Methane-Oxygen Atmospheric Flames
复制标题
预混合甲烷-氧气大气火焰中带正电离子的测量
DOI：
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发表时间：
2017
期刊：
影响因子：
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通讯作者：
A. Farooq
中科院分区：
文献类型：
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作者：
A. Alquaity;Jie Han;M. Chahine;Hatem Selim;M. Belhi;S. M. Sarathy;F. Bisetti;A. Farooq
在燃烧系统中，阳离子和阴离子是化学电离过程的结果。电场可以通过主动控制燃烧过程来减少排放和提高燃烧效率。需要详细的火焰离子化学模型来理解和预测外电场对燃烧等离子体的影响。在这项工作中，利用分子束质谱仪（MBMS）测量了甲烷-氧-氩气燃烧器稳定大气火焰中的离子浓度分布。考虑了稀薄火焰和化学计量火焰来评估离子化学对火焰化学计量的依赖性。对不同温度下的相对离子浓度曲线与数值模拟结果进行了比较，得到了较好的定性结果。然而，对于稀薄火焰，数值模拟极大地歪曲了所选离子的空间分布。为了增强离子机理，提高实验与模拟的一致性，提出了三种修正方法。前两种修饰包括添加阴离子剥离反应以增加阴离子在低温下的重组。第三种修饰是将分离反应恢复到原来的不可逆形式。据我们所知，这项工作首次详细测量了典型甲烷-氧气-氩气大气扁平火焰中的阳离子和火焰温度。本文报道的正离子谱可能有助于验证和改进甲烷-氧火焰的离子化学模型。
ABSTRACT Cations and anions are formed as a result of chemi-ionization processes in combustion systems. Electric fields can be applied to reduce emissions and improve combustion efficiency by active control of the combustion process. Detailed flame ion chemistry models are needed to understand and predict the effect of external electric fields on combustion plasmas. In this work, a molecular beam mass spectrometer (MBMS) is utilized to measure ion concentration profiles in premixed methane–oxygen argon burner-stabilized atmospheric flames. Lean and stoichiometric flames are considered to assess the dependence of ion chemistry on flame stoichiometry. Relative ion concentration profiles are compared with numerical simulations using various temperature profiles, and good qualitative agreement was observed for the stoichiometric flame. However, for the lean flame, numerical simulations misrepresent the spatial distribution of selected ions greatly. Three modifications are suggested to enhance the ion mechanism and improve the agreement between experiments and simulations. The first two modifications comprise the addition of anion detachment reactions to increase anion recombination at low temperatures. The third modification involves restoring a detachment reaction to its original irreversible form. To our knowledge, this work presents the first detailed measurements of cations and flame temperature in canonical methane–oxygen-argon atmospheric flat flames. The positive ion profiles reported here may be useful to validate and improve ion chemistry models for methane-oxygen flames.