Study on cetane number dependence of diesel surrogates/air weak flames in a micro flow reactor with a controlled temperature profile
Study on cetane number dependence of diesel surrogates/air weak flames in a micro flow reactor with a controlled temperature profile
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DOI：
10.1016/j.proci.2012.06.162
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发表时间：
2013
期刊：
影响因子：
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通讯作者：
Satoshi Suzuki;M. Hori;H. Nakamura;T. Tezuka;S. Hasegawa;K. Maruta
中科院分区：
文献类型：
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作者：
Satoshi Suzuki;M. Hori;H. Nakamura;T. Tezuka;S. Hasegawa;K. Maruta
采用微流控反应器研究了化学计量比柴油替代物/空气混合气的着火和燃烧特性。五种柴油替代物（正十六烷、正癸烷、正庚烷、异十六烷和α-甲基萘）具有低蒸气压，被用作微流反应器的燃料。通过改变反应器入口混合气流速，观察到三种火焰。在低速区，燃料的多级氧化过程（弱火焰）可以观察到分离的多个稳定火焰。在780 K附近的弱火焰中，当使用大的正构烷烃作为燃料时，观察到冷火焰作为第一阶段氧化。着重于这种流速条件下，弱火焰响应十六烷值的变化进行了检查，在大气压下。通过改变正十六烷和异十六烷的混合比（柴油PRF）或使用具有不同十六烷值的纯燃料两种方式来改变十六烷值。两种情况下不同十六烷值下所观察到的弱火焰的变化趋势表明，随着十六烷值的降低，第一次氧化（冷火焰）的光度变弱，第一次和第三次反应向高温区移动。本反应器的一般点火和各种低蒸气压燃料的特性的检查能力进行了论证。对正十六烷和异十六烷进行了气体取样和分析。根据CH_2O浓度分布，证实了正十六烷弱火焰的火焰结构与正庚烷的火焰结构相似。一维稳态模拟的详细反应动力学的预测与多阶段氧化过程的趋势和CH 2 O的轮廓除了异十六烷的情况下同意。异十六烷的测量曲线表明，CH 2 O在远高于预测的温度下开始增加，并且所采用的异十六烷化学模型高估了低温反应。
Ignition and combustion characteristics of a stoichiometric gaseous diesel surrogates/air mixtures were investigated using a micro flow reactor with a controlled temperature profile. Five diesel surrogates (n-cetane, n-decane, n-heptane, iso-cetane, and α-methylnaphthalene), which have low vapor pressures, were applied as fuels to the micro flow reactor. Three kinds of flames were observed by changing the mixture flow velocity at the inlet of the reactor. At the low velocity region, multi-stage oxidation process of the fuel (weak flames) can be observed as separated multiple stationary flames. A cool flame was observed as first-stage oxidation in the weak flames around 780K, when applying large n-alkanes as fuel. Focusing on this flow velocity condition, weak flame responses to cetane number variations were examined at atmospheric pressure. The cetane number was varied by two ways; changing mixing ratio of n-cetane and iso-cetane (diesel PRF); or using pure fuels with different cetane numbers. Trends of the observed weak flames at different cetane number in both cases showed that luminosity from the first oxidation (cool flame) became weaker, and the first and third reactions shift to high temperature region with the decrease of the cetane number. The capability of the present reactor for examination of the general ignition and characteristics of various low-vapor-pressure fuels was demonstrated. Gas sampling and analysis were conducted for n-cetane and iso-cetane. According to CH2O concentration profile, it was confirmed that the flame structure of n-cetane weak flame was similar to that of n-heptane. The predictions of 1D steady simulations with detailed reaction kinetics agreed with the trends of the multi-stage oxidation processes and the CH2O profiles except the iso-cetane case. Measured profile of iso-cetane showed that CH2O started increasing in the temperature much higher than the prediction and that the employed chemical model for iso-cetane overestimated the low temperature reaction.