Comparison of Particle Size Measurements with Laser-Induced Incandescence, Mass Spectroscopy, and Scanning Mobility Particle Sizing in a Laminar Premixed Ethylene/Air Flame

Abstract

Particle size distribution functions (PSDF) and mean particle sizes have been determined in a laminar premixed ethylene/air flame with three different experimental approaches: photo-ionization mass spectrometry (PIMS), scanning mobility particle sizing (SMPS), and laser-induced incandescence (LII). The main goal of this investigation was the cross-validation of these three methods used at our institute for the determination of particle sizes in a great variety of flames or exhaust gases. We found good agreement between the three methods in the ranges where they are comparable as well as a complementary behavior for the different size ranges. PIMS and SMPS are able to measure the particle size distribution functions with good resolution. PIMS is favorable in detecting the smallest particles (< 6 nm) and thereby able to detect even bimodal distributions of the soot precursor particles. SMPS and LII are suitable in the mid- and upper range of the particle sizes (> 2 nm and > 3 nm, respectively). LII offers the particular advantage of being a non-intrusive method. This makes it applicable in extreme environments, such as high pressure flames, as well as in very sensitive flames because no probe is needed.