Detailed modeling of polycyclic aromatic hydrocarbon and soot formation employing theory and experiments

为了消除多环芳烃（PAHs）和随后形成的煤烟颗粒对人类健康和环境的有害影响，许多政府和机构正在引入越来越严格的法规。为了开发符合这些法规的燃烧控制技术，必须了解和准确模拟燃料分解的化学动力学，特别是多环芳烃的形成。虽然大多数现有文献主要集中在简单燃烧系统的定量化学动力学建模上，但详细了解复杂的多环芳烃形成和生长机制及其对烟尘产生的影响仍然是燃烧研究的核心挑战之一。拟议项目的目标是生成和测试导致烟尘产生的多环芳烃形成的新化学动力学机制。首先，通过理论和实验方法提高对第二芳环形成的认识。麻省理工学院格林小组开发的反应机制发生器（RMG）将得到增强，以生成可靠、详细的动力学机制。麻省理工学院格林小组提供的时间分辨光电离飞行时间质谱仪和激光吸收光谱仪的组合将用于测量气相自由基反应的特定产物分支比以及依赖温度和压力的化学动力学。然后，将首次探索导致快速烟灰形成的替代途径，包括共振稳定的多环芳烃自由基。目前提出的许多路径似乎太慢或太可逆，无法解释实验观察。最后，生成的化学动力学机制将用于计算层流稳定和时间相关，一维和二维，预混和非预混甲烷，乙烯，苯和乙炔火焰中烟灰产生的混合矩量方法模型。

To combat the harmful effects of polycyclic aromatic hydrocarbons (PAHs) and subsequently formed soot particles on human health and the environment, many governments and institutions are introducing increasingly stringent regulations. To develop combustion control techniques that allow the compliance with these regulations, it is essential to understand and to accurately model the chemical kinetics of fuel decomposition and especially PAH formation. While most of the available literature focuses mainly on the quantitative chemical kinetic modeling of simple combustion systems, a detailed understanding of the complex PAH formation and growth mechanisms and their influence on soot production continues to be one of the central challenges in combustion research. The proposed project targets the generation and testing of new chemical kinetic mechanisms for PAH formation leading to soot production. First, the understanding of the second aromatic ring formation will be improved with theoretical and experimental methods. The Reaction Mechanism Generator (RMG) developed in the Green Group at MIT will be enhanced to allow the generation of reliable, detailed kinetic mechanisms. The combination of a time-resolved photoionization time-of-flight mass spectrometer and a laser absorption spectroscopy apparatus available in the Green Group at MIT will be employed to measure specific product-branching ratios of gas-phase radical reactions and temperature- and pressure-dependent chemical kinetics. Then, alternative pathways leading to fast soot formation will be explored, for the first time including resonantly stabilized PAH radicals. Many of the currently proposed routes appear to be too slow or too reversible to explain experimental observations. Finally, the generated chemical kinetic mechanisms will be used to compute soot production with the Hybrid Method of Moments model in laminar steady and time-dependent, one- and two-dimensional, premixed and non-premixed methane, ethylene, benzene, and acetylene flames.