Soot Evolution and Control

This research has provided an understanding of the formation of earliest soot particles soot precursor particles in combustion processes, and thus indicates strategies to intervene in their formation in various types of combustion devices. Major progress was achieved in characterizing the chemical composition and the carbonization of soot precursor particles that have been found in laboratory flames. The use of TEN has permitted the observation of precursor particles in flames fueled by CH4, C2H4 and C2H2. The transformation of the liquid-like precursor particles into solid clustered aggregates by the carbonization process was displayed. The conversion kinetics of carbonization ere studied because this process converts the young more easily oxidized young particles into the more inert carbonaceous aggregates that are likely to be released to the surroundings. A major effort was in the area of chemical analysis of the precursor particles as studied by use of the LANMA-500 instrument at the NIST. These studies revealed the precursor particles to consist of PAHs and that these compounds are embers of the stabilomer classes predicted by Stein and Fahr to be the most chemically stable. Our last task has related to the development of crystallinity in precursor particles and in carbonaceous aggregates formed in hydrocarbon combustion.