(115i) Soot Oxidation Premixed Flames

Soot has significant impact on human health and radiative forcing. This study focuses on soot oxidation and fragmentation as a function of fuel properties and temperature. A two-stage premixed burner for soot formation and oxidation is used. Rates of soot oxidation are evaluated based on measurement of particle size distribution (PSD) in the first and second stage burners. In this study, a fuel rich ethylene?air flame is used to form soot which is then oxidized under different lean conditions (Φ = 0.7 - 0.9). PSDs are determined using a Scanning Mobility Particle Sizer as well as an aerosol spectrometer allowing counts of soot particles ranging from 3 nm to over 300 nm. Mass calculated from the PSD's is compared to mass collected by using filters. These measurements allow us to obtain rate information during oxidation. Presently the results for PSD, mass and number concentration are indicative that soot fragmentation is occurring in the second burner.

This information will be used to estimate the soot oxidation rates and elucidation of the role of OH, O and O2. Improved rates will allow for prediction of engine emissions. Future work will include similar studies using surrogates and mixtures of liquid fuels.