AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
An Investigation of Soot Oxidation-Induced Fragmentation in a Two-Stage Burner
HOSSEIN GHIASSI, Isabel C. Jaramillo, JoAnn S. Lighty, University of Utah
Abstract Number: 353 Working Group: Combustion
Abstract Soot particles are destroyed in flames through oxidation by OH and O2. Under high O2 conditions, our results suggest that fragmentation of soot aggregates occurs. Due to an increase in surface area, this would result in an increase of oxidation. Soot fragmentation studies were carried out experimentally in a two-stage burner, where soot was produced in a first-stage premixed burner, while in a second stage, the soot was oxidized under slightly-rich conditions. Temperature, particle size distributions (PSD), and measurements of specific gas-phase compounds were performed to characterize the flame. Fragmentation was reflected by an observable increase in the number concentration of ultrafine particles. Different oxidizer gas mixture, oxygen/helium, oxygen/argon, and oxygen/nitrogen, were used to investigate how these gas environments affect the fragmentation. Fragmentation has been hypothesized to be caused by oxygen diffusion into the particle or bridges between particles, causing it to break apart. The diffusion of oxygen varies in these different binary mixtures. It was observed that soot fragmentation occurred in the oxidation region to differing extents related to the gas mixture. The results confirmed the importance of oxygen diffusion in the particle breakup.