Development of a Reduced <i>n</i>‑Decane/α-Methylnaphthalene/Polycyclic Aromatic Hydrocarbon Mechanism and Its Application for Combustion and Soot Prediction

In this work, a reduced n-decane/α-methylnaphthalene/polycyclic aromatic hydrocarbon (PAH) kinetic mechanism for calculation of combustion and soot behavior of diesel and its surrogate fuel was developed. This mechanism consists of the pyrolysis of n-decane (C10H22) and α-methylnaphthalene (C10H7CH3), C0–C3 core species reaction, and the formation of initial benzene and PAHs, including 77 species and 287 reactions. The pyrolysis reaction of fuel was obtained by pathway analysis from a detailed mechanism, while the reactions of core species and PAHs were reduced by a directed relation graph with error propagation, computational singular perturbation method, and direct sensitivity analysis, sequentially. The mechanism was validated by the mole fraction of main species and key PAH species in the ethylene premixed flame, ignition delay times of pure and mixed fuel in shock tubes, and the concentrations of major species in jet-stirred reactors. Finally, the new developed mechanism was coupled with a soot phenomenological model, where A4 was employed as the precursor in soot inception, and a multi-dimensional turbulent model, to calculate the combustion and soot emission processes in a diesel engine. The pressure in the cylinder, apparent heat release rate, and normalized soot fraction were obtained in this calculation. Both the fundamental modeling and engine modeling agree well with the data from the literature.本研究开发了一套简化的正癸烷/α-甲基萘/多环芳烃（Polycyclic Aromatic Hydrocarbon, PAH）动力学机理，用于计算柴油及其替代燃料的燃烧与炭烟生成特性。该机理涵盖正癸烷（C10H22）与α-甲基萘（C10H7CH3）的热解过程、C0–C3核心组分的反应路径，以及初始苯与多环芳烃的生成过程，总计包含77种组分与287个基元反应。燃料的热解反应由详细机理通过路径分析推导得到，而核心组分与多环芳烃的相关反应则依次通过有向关系图结合误差传播、计算奇异摄动法与直接敏感性分析完成简化。本机理通过多组实验数据完成验证：包括乙烯预混火焰中主要组分与关键多环芳烃组分的摩尔分数、纯燃料与混合燃料在激波管中的点火延迟时间，以及射流搅拌反应器内主要组分的浓度。最后，将本研究开发的新型机理与以A4为炭烟成核前驱体的炭烟现象学模型、多维湍流模型耦合，用于模拟柴油机内的燃烧与炭烟排放过程，计算得到缸内压力、表观放热率与归一化炭烟分数。无论是基础机理建模还是柴油机模拟结果，均与文献报道的数据吻合良好。