Cool diffusion flames of butane isomers activated by ozone in the counterflow
Cool diffusion flames of butane isomers activated by ozone in the counterflow
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DOI：
10.1016/j.combustflame.2017.12.034
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发表时间：
2018-05-01
影响因子：
4.4
通讯作者：
Sarathy, S. Mani
中科院分区：
文献类型：
--
作者：
Alfazazi, Adamu;Al-Omier, Abdullah;Sarathy, S. Mani
低温燃烧发动机中的点火由低温氧化动力学和扩散传输之间的耦合控制。因此，详细了解冷火焰中的热释放、低温氧化化学和分子输运的耦合效应对于推进新的燃烧概念是必要的。本研究提供了一个理解的低温冷火焰行为丁烷异构体在逆流配置通过添加臭氧。研究了不同应变率下丁烷异构体冷火焰的起燃极限和熄灭极限。结果表明，在低应变率和中等应变率下，加入臭氧，丁烷冷扩散火焰的建立是成功的。异丁烷具有比正丁烷更低反应性，如冷却火焰引发所需的更高燃料摩尔分数和更低的熄灭应变速率极限所示。臭氧的加入对冷扩散火焰的形成和维持有显著影响;由于丁烷异构体的无臭氧冷扩散火焰即使在高燃料摩尔分数下也不能建立。利用飞行时间质谱仪对正丁烷冷扩散火焰的结构进行了定性研究。采用详细的化学动力学模型和分子输运进行了数值模拟，以模拟测试燃料的冷扩散火焰的熄灭极限。该模型定性地捕捉到了燃料和臭氧水平的实验趋势，但过度预测了火焰的熄灭极限。涉及低温物种的反应主要控制冷火焰的熄灭极限。模拟结果被用来了解甲基支化对正丁烷和异丁烷冷扩散火焰行为的影响。(C)2018燃烧研究所爱思唯尔公司出版All rights reserved.
Ignition in low temperature combustion engines is governed by a coupling between low-temperature oxidation kinetics and diffusive transport. Therefore, a detailed understanding of the coupled effects of heat release, low-temperature oxidation chemistry, and molecular transport in cool flames is imperative to the advancement of new combustion concepts. This study provides an understanding of the low temperature cool flame behavior of butane isomers in the counterflow configuration through the addition of ozone. The initiation and extinction limits of butane isomers' cool flames have been investigated under a variety of strain rates. Results revealed that, with ozone addition, establishment of butane cool diffusion flames was successful at low and moderate strain rates. iso-Butane has lower reactivity than n-butane, as shown by higher fuel mole fractions needed for cool flame initiation and lower extinction strain rate limits. Ozone addition showed a significant influence on the initiation and sustenance of cool diffusion flames; as ozone-less cool diffusion flame of butane isomers could not be established even at high fuel mole fractions. The structure of a stable n-butane cool diffusion flame was qualitatively examined using a time of flight mass spectrometer. Numerical simulations were performed using a detailed chemical kinetic model and molecular transport to simulate the extinction limits of the cool diffusion flames of the tested fuels. The model qualitatively captured experimental trends for both fuels and ozone levels, but over-predicted extinction limits of the flames. Reactions involving low-temperature species predominantly govern extinction limits of cool flames. The simulations were used to understand the effects of methyl branching on the behavior of n-butane and iso-butane cool diffusion flames. (C) 2018 The Combustion Institute. Published by Elsevier Inc. All rights reserved.