Evaluation of Combustion Mechanisms Using Global Uncertainty and Sensitivity Analyses: A Case Study for Low‐Temperature Dimethyl Ether Oxidation
Evaluation of Combustion Mechanisms Using Global Uncertainty and Sensitivity Analyses: A Case Study for Low‐Temperature Dimethyl Ether Oxidation
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DOI：
10.1002/kin.20877
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发表时间：
2014-11
影响因子：
1.5
通讯作者：
A. Tomlin;E. Agbro;V. Nevrlý;Jakub Dlabka;M. Vasinek
中科院分区：
文献类型：
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作者：
A. Tomlin;E. Agbro;V. Nevrlý;Jakub Dlabka;M. Vasinek
对目前描述二甲醚低温氧化的三种机制进行了全局不确定性分析（Aramco Mech 1.3, Metcalfe et al., Int J Chem Kinet 2013, 45, 638–675；Zheng et al., Proc Combust Inst 2005, 30, 1101–1109；Liu et al., Combust Flame 2013, 160, 2654–2668) 应用于模拟与常压流反应器和高压点火延迟的现有数据相对应的物质浓度（CH2O、H2O2、CH3OCHO）。当在全局采样方法中纳入反应速率的不确定性时，预测目标的分布可以跨越几个数量级。然而，实验概况落在预测的不确定性限度内。然后使用高维模型表示进行基于方差的敏感性分析。预测不确定性的主要贡献来自 CH3OCH2 + O2 系统，其中异构化、增长、链支化、二次 OH 形成和过氧-过氧反应都发挥了作用。在所有情况下，描述采样反应速率和预测输出之间关系的响应面都很复杂。参数之间的高阶相互作用对输出方差有显着贡献，并且对于所研究的任何条件，没有单一反应通道占主导地位。灵敏度散点图表明，许多不同的参数组合可以与特定的实验数据组获得良好的一致性。然后，阿美公司的计划根据 Eskola 等人最近研究的数据进行了更新。 （J Phys Chem A，出版中），与当前使用的值相比，CH3OCH2O2 CH2OCH2O2H 和 CH2OCH2O2H OH+2CH2O 的速率呈现出完全不同的温度和压力依赖性，并且包括井跳跃通道。 Eskola 的更新使单独使用时与实验的一致性变得更差。然而，如果随后降低 CH2OCH2O2H + O2 通道的速率，则可以获得非常好的一致性。由于响应面的复杂性，该通道的调整仍然是推测性的。建议进一步详细研究 CH3OCH2O2 + O2、CH2OCH2O2H + O2 系统的温度和压力依赖性，以减少当前低温条件下二甲醚机理的不确定性。
A global uncertainty analysis is performed for three current mechanisms describing the low-temperature oxidation of dimethyl ether (Aramco Mech 1.3, Metcalfe et al., Int J Chem Kinet 2013, 45, 638–675; Zheng et al., Proc Combust Inst 2005, 30, 1101–1109; Liu et al., Combust Flame 2013, 160, 2654–2668) with application to simulations of species concentrations (CH2O, H2O2, CH3OCHO) corresponding to existing data from an atmospheric pressure flow reactor and high-pressure ignition delays. When incorporating uncertainties in reaction rates within a global sampling approach, the distributions of predicted targets can span several orders of magnitude. The experimental profiles, however, fall within the predictive uncertainty limits. A variance-based sensitivity analysis is then undertaken using high dimensional model representations. The main contributions to predictive uncertainties come from the CH3OCH2 + O2 system, with isomerization, propagation, chain-branching, secondary OH formation, and peroxy–peroxy reactions all playing a role. The response surface describing the relationship between sampled reaction rates and predicted outputs is complex in all cases. Higher order interactions between parameters contribute significantly to output variance, and no single reaction channel dominates for any of the conditions studied. Sensitivity scatter plots illustrate that many different parameter combinations could lead to good agreement with specific sets of experimental data. The Aramco scheme is then updated based on data from a recent study by Eskola et al. (J Phys Chem A, in press), which presents quite different temperature and pressure dependencies for the rates of CH3OCH2O2 CH2OCH2O2H and CH2OCH2O2H OH+2CH2O compared with currently used values and includes well skipping channels. The updates from Eskola worsen the agreement with experiments when used in isolation. However, if the rate of the CH2OCH2O2H + O2 channel is subsequently reduced, very good agreement can be achieved. Owing to the complex nature of the response surface, the tuning of this channel remains speculative. Further detailed studies of the temperature and pressure dependence of the CH3OCH2O2 + O2, CH2OCH2O2H + O2 system are recommended to reduce uncertainties within current dimethyl ether mechanisms for low-temperature conditions.