Study on pressure dependences of ethanol oxidation by separated weak flames in a micro flow reactor with a controlled temperature profile
Study on pressure dependences of ethanol oxidation by separated weak flames in a micro flow reactor with a controlled temperature profile
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DOI：
10.1016/j.proci.2012.06.101
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
H. Nakamura;A. Yamamoto;M. Hori;T. Tezuka;S. Hasegawa;K. Maruta
中科院分区：
文献类型：
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作者：
H. Nakamura;A. Yamamoto;M. Hori;T. Tezuka;S. Hasegawa;K. Maruta
在微流反应器中，采用分离弱火焰技术，研究了化学计量比的乙醇/空气混合物的氧化过程及其压力依赖性。随着压力的增加，稳定在低温侧的第一弱火焰向低温侧移动，亮度峰值增大。第二个弱火焰的光度峰值在P=1 ~ 2atm时增大，在P=2 ~ 5atm时减小，并稳定在高温侧。由Saxena和威廉姆斯提出的详细的乙醇机制（UCSD机制）计算的热释放率（HRR）分布的压力依赖性与实验的光度分布一致。研究了基元反应对分离弱火焰HRR峰值的贡献。结果表明，第一弱火焰以燃料氧化为CO为特征，第二弱火焰以CO氧化和氢氧反应为特征。反应路径分析表明，在第一个弱火焰阶段，HO 2生成反应、H+O2（+M）惠HO 2（+M）反应、CH 3CHO氧化反应以及C2 H4和C2 H5之间的反应主要表现为压力依赖性。用Marinov机理（LLNL机理）进行了计算，虽然质量燃烧速度和点火延迟时间的压力依赖性与UCSD机理的结果一致，但HRR曲线的压力依赖性与UCSD机理的结果不一致。这两种机制的HRR曲线的压力依赖性的差异主要是由于HO 2形成反应的不同压力依赖性。UCSD机理高估了高压条件下第一个弱火焰处反应性的增加，而LLNL机理低估了第一个弱火焰处反应性的增加。
Detailed oxidation process of a stoichiometric ethanol/air mixture and its pressure dependence were examined based on separated weak flames in a micro flow reactor with a controlled temperature profile. With the increase of pressure, the first weak flame, which is stabilized at the lower temperature side, shifted to the low temperature side, and the peak value of its luminosity increased. The peak value of luminosity at the second weak flame, which is stabilized at the higher temperature side, increased from P=1 to 2atm, then decreased from P=2 to 5atm. Pressure dependences of the computed heat release rate (HRR) profiles with detailed ethanol mechanism developed by Saxena and Williams (UCSD mechanism) agreed with those of the experimental luminosity profiles. The contributions of elementary reactions to the peak values of HRR at the separated weak flames were investigated. Results showed that the first weak flame was characterized by the oxidation from the fuel to CO and the second weak flame was characterized by the CO oxidation and hydrogen-oxygen reactions. Reaction path analysis was conducted and the HO2formation reaction, H+O2(+M)⇔HO2(+M), CH3CHO oxidation reactions, and reactions between C2H4and C2H5showed main pressure dependences at the first weak flame. Computation with Marinov’s mechanism (LLNL mechanism) was conducted and pressure dependences of the HRR profiles did not agree with those obtained with UCSD mechanism, although pressure dependences of mass burning velocities and ignition delay times by these two mechanisms agreed well. The difference in the pressure dependences of the HRR profiles by these two mechanisms would be mainly due to the different pressure dependence of the HO2formation reaction. The increase of reactivity at the first weak flame in elevated pressure condition was overestimated in UCSD mechanism, while it was underestimated in LLNL mechanism.