Kinetic Modeling Study of the Ignition Process of Homogeneous Charge Compression Ignition Engine Fueled with Three-Component Diesel Surrogate
Kinetic Modeling Study of the Ignition Process of Homogeneous Charge Compression Ignition Engine Fueled with Three-Component Diesel Surrogate
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DOI：
10.1021/ie303406k
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发表时间：
2013-03-13
影响因子：
4.2
通讯作者：
Lang, Jing
中科院分区：
文献类型：
--
作者：
Xiao, Gan;Zhang, Yusheng;Lang, Jing
已经提出了一种改进的替代柴油燃料组合物来模拟均质充量压缩点火（HCCI）发动机条件下柴油燃料的自燃时间。替代燃料被建模为正庚烷、甲苯和环己烷的混合物。通过合并每种化学物质成熟的可用化学动力学子结构，构建了由 1140 个物质和 4590 个反应组成的详细机制。所选柴油替代燃料成分的最佳比例，正庚烷/甲苯/环己烷 = 8:1:1，是通过试错混合方法确定的。在数值上，从所提出的新模型的零维单区代码获得的建模热释放率根据详细的单组分和双组分动力学模型以及参考的实验发动机数据进行了深入验证。所得结果表明，新模型与实验数据吻合良好，能够有效捕捉自燃角和整个燃烧过程。进一步进行了灵敏度分析和通量分析，以了解柴油中不同烃类的作用，并确定了添加环己烷后抑制点火所涉及的关键基元反应。结果表明，环己烷是一种高反应性物质，可以用作控制两个燃烧阶段之间的延迟的“调节旋钮”。
An improved surrogate diesel fuel composition has been proposed to simulate the autoignition time of diesel fuel under homogeneous charge compression ignition (HCCI) engine conditions. The surrogate fuel is modeled as a blend of n-heptane, toluene, and cyclohexane. Detailed mechanisms consisting of 1140 species and 4590 reactions were constructed by merging well-developed available chemical kinetics substructures for each chemical species. The optimal ratio of the selected diesel surrogate fuel components, n-heptane/toluene/cyclohexane = 8:1:1, was determined using trial-and-error blend methods. Numerically, the modeled heat-release rate obtained from a zero-dimensional single-zone code for the proposed new model was intensively validated against detailed single- and two-component kinetic models together with the referenced experimental engine data. The obtained results show that the new model provides a remarkable agreement with the obtained experimental data and can capture the autoignition angle and the whole combustion process effectively. Sensitivity analysis and flux analysis were further conducted to understand the roles of the different hydrocarbon classes in diesel fuels, and the key elementary reactions involved in ignition inhibition upon the addition of cyclohexane were identified. It is demonstrated that cyclohexane is a highly reactive species and can be used as a "tuning knob" to control the delay between the two stages of combustion.