Mass, Mobility, Volatility, and Morphology of Soot Particles Generated by a McKenna and Inverted Burner

Particle mass, mobility, volatile mass fraction, effective density, mass concentration, mass-mobility exponent, and particle morphology were measured from soot generated from a premixed flame (McKenna burner) and an inverted diffusion flame over a range of equivalence ratios. It was found that the mass fraction of volatile material on the soot from the McKenna burner could be up to 0.83 at a high equivalence ratio, but there was no measurable volatile material on the soot from the inverted burner. The inverted burner can produce soot at different mass-mobility exponents, ranging from 2.23 to 2.54, over a range of global equivalence ratios of 0.53-0.67, while the mass-mobility exponent ranges from 2.19 to 2.99 for fresh soot and 2.19 to 2.81 for denuded soot for the McKenna burner at equivalence ratios of 2.0-3.75. Transmission electron microscopy analysis of inverted burner soot shows that a range of particle morphologies is present at a given global equivalence ratio, likely due to different local equivalence ratios and flame conditions in the diffusion flame. Primary particle diameter tends to increase with aggregate size, which could contribute to the mass-mobility exponent being well above 2. Copyright 2013 American Association for Aerosol Research