Chemistry and Physics of Incipient Soot in Laminar Premixed Flames

煤烟是空气微粒污染物的主要来源。其排放源包括柴油和飞机发动机。颗粒烟灰与死亡率和流动性增加以及一系列长期健康影响有关。由颗粒烟灰排放产生的环境气溶胶也以一种尚未完全了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烟尘的粒径分布和化学成分。在内燃机中，烟尘形成的机理和动力学仍然是一个未解决的科学问题。主要的科学挑战包括缺乏以时间分辨的方式探测新生烟灰生长过程中的化学成分和尺寸/质量变化的能力。该研究项目将开发和测试一种新的热解吸化学电离迁移率/质谱（TDCIMMS）技术，以探测一系列实验室火焰中新生烟尘颗粒的化学成分和粒径分布。其他一些技术，包括探针取样/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，这对我们理解烟灰如何在分子水平上成核和生长至关重要。它还将有助于提供所需的数据，以开发更先进的煤烟形成的数值模型，包括颗粒大小、化学成分和光学性质。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。这项研究将为下一代烟尘模型的开发提供关键数据，这些模型将应用于高效、低排放的发动机设计和优化。这项研究的合作性质将结合燃烧和气溶胶研究的专业知识，在分子水平上解决烟灰形成的复杂问题。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发展和应用的进展，这些仪器用于研究化学反应流动中的颗粒形成问题。下一代烟尘模型开发的成功将使燃烧器设计的能力达到一个水平，从而使进一步的PM监管开发变得可行。

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.