Stability Enhancement of Ozone-Assisted Laminar Premixed Bunsen Flames in Nitrogen Co-Flow
Stability Enhancement of Ozone-Assisted Laminar Premixed Bunsen Flames in Nitrogen Co-Flow
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DOI：
10.1016/j.combustflame.2013.09.023
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发表时间：
2014-04
影响因子：
4.4
通讯作者：
T. Vu;S. Won;T. Ombrello;M. Cha
中科院分区：
文献类型：
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作者：
T. Vu;S. Won;T. Ombrello;M. Cha
臭氧（O3）被认为是最强的氧化剂之一，因此被广泛应用于许多领域。通常在燃烧领域，非热等离子体和燃烧系统的组合已经被研究，重点是臭氧对火焰传播速度和点火特性的影响。在此，我们利用共流燃烧器和介质阻挡放电，在室温和常压下，实验研究了臭氧对甲烷/空气和丙烷/空气预混火焰在全范围等效比下喷出的影响。结果表明，在臭氧条件下，喷管喷焰时刻的出口射流速度（喷焰速度）显著提高，同时提高了贫油和富油混合气的可燃性极限。臭氧对非化学计量混合物的喷射速度有更强的百分比增强作用，而在化学计量条件下，两种燃料的最小增强作用与臭氧浓度测试范围呈线性正相关，最高可达3810 ppm。通过化学动力学模拟，确定了由于层流燃烧速度的改变，实验观察到的放空速度增强的趋势。O3+ N2→O + O2+ N2和O3+ H→O2+ OH两条臭氧分解路径是最具控制性的步骤。这些反应，再加上每种燃料的燃料消耗特性，决定了层流燃烧速度的促进程度，支持了臭氧添加后排气速度的实验观察。
Ozone (O3) is known as one of the strongest oxidizers and therefore is widely used in many applications. Typically in the combustion field, a combination of non-thermal plasma and combustion systems have been studied focusing on the effects of ozone on flame propagation speeds and ignition characteristics. Here, we experimentally investigated the effects of ozone on blowoff of premixed methane/air and propane/air flames over a full range of equivalence ratios at room temperature and atmospheric pressure by using a co-flow burner and a dielectric barrier discharge. The results with ozone showed that a nozzle exit jet velocity at the moment of flame blowoff (blowoff velocity) significantly increased, and flammability limits for both fuel-lean and rich mixtures were also extended. Ozone had stronger effects of percent enhancement in the blowoff velocity for off-stoichiometric mixtures, while minimum enhancements could be observed around stoichiometric conditions for both fuels showing linear positive dependence on a tested range of ozone concentration up to 3810 ppm. Through chemical kinetic simulations, the experimentally observed trends of the enhancement in blowoff velocity were identified as a result of the modification of the laminar burning velocity. Two ozone decomposition pathways of O3+ N2→ O + O2+ N2and O3+ H → O2+ OH were identified as the most controlling steps. These reactions, coupled with fuel consumption characteristics of each fuel determined the degree of promotion in laminar burning velocities, supporting experimental observations on blowoff velocities with ozone addition.