Negative pressure dependence of mass burning rates of H2/CO/O2/diluent flames at low flame temperatures
Negative pressure dependence of mass burning rates of H2/CO/O2/diluent flames at low flame temperatures
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DOI：
10.1016/j.combustflame.2009.08.009
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发表时间：
2010-04-01
影响因子：
4.4
通讯作者：
Ju, Yiguang
中科院分区：
文献类型：
--
作者：
Burke, Michael P.;Chaos, Marcos;Ju, Yiguang
实验测量了H-2/CO/O-2/稀释剂火焰的燃烧速率，分析了关键反应和动力学路径，并对多种条件进行了模拟研究：当量比为0.85~2.5，火焰温度为1500~1800K，压力为1~25atm，CO燃料馏分为0~0.9，稀释剂He浓度为0.8，Ar浓度为0.6，CO2浓度为0.4。实验数据表明，对于所有当量比和CO分数高达0.5的情况，高压、低火焰温度条件下的燃速与压力负相关。与相同火焰温度的Ar稀释火焰相比，用CO2稀释可以增强压力和温度的依赖性。将实验研究的条件扩展到整体气化联合循环过程中燃气轮机燃烧的典型条件，包括预热混合物和其他稀释剂，如N-2和H 2O，观察到文献模型预测与实验数据之间以及模型预测本身之间的实质性差异-在高压下最高可达三倍。目前的研究结果表明，当前氢气模型中的反应需要几次速率常数的修正，并对最新氢气模型中氢气反应集的充分性提出了质疑，以预测与燃气轮机燃烧中控制NO_2排放相关的高压火焰条件。例如，反应O+OH+M=HO2+M不包括在大多数氢模型中，但这里证明了在其不确定范围内使用速率对稀薄高压火焰的预测有显著影响。需要进一步研究，以减少在纯和混合浴气中H+O-2(+M)=HO2(+M)的第三体碰撞效率和衰减行为的不确定性，在较高温度下HO2与其他自由基物种反应的速率常数的不确定性，以及在目前条件下变得重要的O+OH+M反应的速率常数的不确定性，以便适当地描述高压H-2或H-2/CO火焰的动力学和预测全球行为。(C)2009年，燃烧研究所。爱思唯尔公司出版，版权所有。
Experimental measurements of burning rates, analysis of the key reactions and kinetic pathways, and modeling studies were performed for H-2/CO/O-2/diluent flames spanning a wide range of conditions: equivalence ratios from 0.85 to 2.5, flame temperatures from 1500 to 1800 K, pressures from 1 to 25 atm, CO fuel fractions from 0 to 0.9, and dilution concentrations of He up to 0.8, Ar up to 0.6, and CO2 up to 0.4. The experimental data show negative pressure dependence of burning rate at high pressure, low flame temperature conditions for all equivalence ratios and CO fractions as high as 0.5. Dilution with CO2 was observed to Strengthen the pressure and temperature dependence compared to Ar-diluted flames of the same flame temperature. Simulations were performed to extend the experimentally studied conditions to conditions typical of gas turbine combustion in Integrated Gasification Combined Cycle processes, including preheated mixtures and other diluents such as N-2 and H2O.Substantial differences are observed between literature model predictions and the experimental data as well as among model predictions themselves - up to a factor of three at high pressures. The present findings suggest the need for several rate constant modifications of reactions in the current hydrogen models and raise questions about the sufficiency of the set of hydrogen reactions in most recent hydrogen models to predict high pressure flame conditions relevant to controlling NO, emissions in gas turbine combustion. For example, the reaction O + OH + M = HO2 + M is not included in most hydrogen models but is demonstrated here to significantly impact predictions of lean high pressure flames using rates within its uncertainty limits. Further studies are required to reduce uncertainties in third body collision efficiencies for and fall-off behavior of H + O-2(+M) = HO2(+M) in both pure and mixed bath gases, in rate constants for HO2 reactions with other radical species at higher temperatures, and in rate constants for reactions such as O + OH + M that become important under the present conditions in order to properly characterize the kinetics and predict global behavior of high-pressure H-2 or H-2/CO flames. (c) 2009 The Combustion Institute. Published by Elsevier Inc. All rights reserved.