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.
