Predictions of oxidation and autoignition of large methyl ester with small molecule fuels
Predictions of oxidation and autoignition of large methyl ester with small molecule fuels
复制标题
小分子燃料大甲酯氧化和自燃的预测
DOI：
10.1016/j.fuel.2019.04.056
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发表时间：
2019
期刊：
影响因子：
7.4
通讯作者：
Zhu Lei
中科院分区：
文献类型：
--
作者：
Li Ang;Ji Wenxia;Huang Zhen;Zhu Lei
生物柴油含有大量的甲酯，包括棕榈酸甲酯（MP）、油酸甲酯（MO）、亚油酸甲酯（ML）等。这些大型甲酯的长烷基链和不对称结构导致了动力学模型发展的复杂性。本文提出并开发了大型甲酯的替代燃料。替代模型可以用来代替大甲基酯在预测氧化和自燃性能方面的详细机制。在神经网络图中，燃烧的关键特征与燃料成分呈非线性关系，这表明具有相同官能团的替代物可以表现出与大甲基酯相似的燃烧特性。在替代燃料的配方中，候选燃料包括小种类，如癸酸甲酯、正十六烷、反式-3-己酸甲酯和1,4 -己二烯。为了比较其氧化性能，在层流反应器中进行了点对点实验验证。替代燃料和目标燃料的氧化性能基本一致。替代燃料不仅成功地捕获了不同甲酯反应性的差异，而且还以不同的当量比再现了中间体和产物的物种浓度。为了验证预测自燃特性的性能，将基于代理模型的仿真与以往的实验数据进行了比较。替代模型不仅预测了不同压力和等比值下的点火延迟时间，而且再现了不同条件下表观活化能的变化趋势。综上所述，利用小分子化合物组合动力学模型可以预测大甲酯的氧化和自燃特性，在复杂分子结构燃料动力学模型的开发中具有很大的潜力。
Biodiesel contains large methyl esters including methyl palmitate (MP), methyl oleate (MO), methyl linoleate (ML), etc. Long alkyl chains and asymmetric structures of these large methyl esters lead to complexity in development of kinetic models. In this paper, surrogate fuels for large methyl esters were proposed and developed. Surrogate models can be used to replace the detailed mechanisms of large methyl esters in prediction of oxidation and autoignition properties. Key characteristics in combustion have non-linear relationships with fuel components in a neural network diagram, which indicates that surrogates with the same functional groups can exhibit similar combustion properties as large methyl esters. In formulation of surrogate fuels, candidates consist of small species such as methyl decanoate, n-hexadecane, methyl trans-3-hexenoate, and 1, 4-hexadiene. To compare the oxidation properties, point-to-point experimental validations were conducted in laminar flow reactor. Oxidation properties of surrogate and target fuels were in satisfactory agreements. Surrogate fuels not only successfully captured the discrepancies in reactivity of different methyl esters, but also reproduced species concentrations of intermediate and products at various equivalence ratios. To test the performance in predicting autoignition characteristics, simulations based on surrogate models were compared with previous experimental data. Surrogate models not only predicted ignition delay times at various pressure and equivalence ratios, but also reproduced the trends of apparent activated energy under different conditions. To sum up, oxidation and autoignition characteristics of large methyl esters can be predicted by the combined kinetic model of small molecule compounds, which will have great potentials in the development of kinetic models for fuels with complicated molecular structures.