Measurement of nanoparticles of organic carbonin non-sooting flame conditions

摘要

In this work we compare the results of several nanoparticle measurement techniques with the aim ofinvestigating the formation of nanoparticles in non-sooting to slightly sooting flames. In slightly sootingconditions there is quite good agreement between Differential Mobility Analyser (DMA), Atomic ForceMicroscopy (AFM), and optical measurements on particle size and concentration. However, in rich flamesbelow the onset of soot, DMA measures a strong drop-off in the total particle volume fraction at low fuelto air mixtures, which is not observed in optical or AFM measurements that detect a more gradual decreasein particle concentration with decreasing C/O and almost constant spectroscopic properties. The disagreementis significantly larger than experimental error and is only observed when the particle size distributionincludes solely particles smaller than about 3 nm.Particle losses in the DMA sampling system does not seem to be the only possible reason for justifyingthe discrepancy with the other techniques. Further investigations are necessary in order to characterizechemically and physically this class of nanoparticles which constitute the earliest stage in the formationof particulate carbon.