Chemistry and Physics of Incipient Soot in Laminar Premixed Flames

煤烟是颗粒空气污染物的主要来源。 其排放源包括柴油和飞机发动机。 烟尘颗粒与死亡率和流动率的增加以及一系列长期健康影响有关。 由颗粒烟尘排放产生的环境气溶胶也以一种尚未完全理解的方式影响全球气候。 一般来说，烟尘排放的影响很大程度上取决于颗粒尺寸分布和化学成分。 在内燃机中，碳烟形成的机理和动力学仍然是一个尚未解决的科学问题。 这项研究计划将发展及测试一种新的热脱附化学电离迁移/质谱技术（TDCIMMS），以探测一系列实验室火焰中初生碳黑粒子的化学组成及粒度分布。 其他几种技术，包括探针采样/扫描迁移率粒度仪，热电偶粒子密度测定法，原子力显微镜和透射电子显微镜，将被用来补充TDCIMMS技术。 这项研究将产生实验数据，这些数据对我们理解煤烟如何在分子水平上成核和生长至关重要。 它还将有助于提供开发更先进的烟尘形成数值模型所需的数据，包括颗粒大小，化学成分和光学特性。 这些研究将解决有关新生烟尘形成的机制和速率的几个关键问题。该研究将为下一代碳烟模型的开发提供关键数据，以应用于高效，低排放的发动机设计和优化。 这项研究的合作性质将联合收割机结合燃烧和气溶胶研究的专门知识，以解决在分子水平上形成烟尘的复杂问题。 PI与外部合作者之间的密切合作将有助于快速将实验进展带入模型开发。广泛的影响-拟议的研究将导致一系列关键仪器的开发和应用的进展，用于研究化学反应流中颗粒形成的问题。 下一代碳烟模型开发的成功将使燃烧室设计能力达到一个水平，使进一步的PM调节开发成为可能。

Soot is a major source of particulate air pollutants. Its emission sources include Diesel and aircraft engines. Particulate soot has been linked to increased mortality and mobility rates and a range of long-term health effects. Ambient aerosols resulting from particulate soot emission also impact the global climate in a manner that is yet to be fully understood. In general, the impact of soot emission is determined largely by the particle size distribution and the chemical composition. In combustion engines, the mechanism and kinetics of soot formation remain to be an unresolved scientific problem. The major scientific challenges include a lack of ability to probe the chemical composition and size/mass changes during the growth process of nascent soot in a time resolved manner.This research project will develop and test a novel Thermal Desorption Chemical Ionization Mobility/Mass Spectrometry (TDCIMMS) technique to probe the chemical composition and particle size distribution for nascent soot particles in a series of laboratory flames. Several other techniques, including probe sampling/scanning mobility particle sizer, thermocouple particle densitometry, atomic force microscopy, and transmission electron microscopy, will be utilized to complement the TDCIMMS technique. The research will yield experimental data critical to our understanding of how soot nucleates and grows at the molecular level. It will also help to provide data needed to develop more advanced numerical models of soot formation to include particle size, chemical composition and optical properties. Intellectual Merit The studies will address several key questions concerning the mechanism and rates of nascent soot formation. The research will provide data critical to the development of the next generation of soot models to be applied in highly-efficient, low-emission engine design and optimization. The collaborative nature of the research will combine expertise of combustion and aerosol research to tackle the complex problem of soot formation at the molecular level. The close collaboration between the PIs and their outside collaborators will help to quickly bring experimental advances into model development. Broad Impact The proposed study will lead to advances in the development and application of an array of critical instrumentation for studying the problem of particle formation in chemically reacting flows. The success in the development of the next generation of soot models will bring the capability of combustor design to a level that further PM regulatory development can be made feasible.