The effect of temperature on the condensed phases formed in fuel-rich premixed benzene flames

The sooting structure of premixed fuel-rich atmospheric pressure benzene flames burning at the same C/O molar ratio = 0.8 was studied in different temperature conditions (T-max = 1720 K and 1810 K) by changing the cold gas velocity. Compositional profiles of gaseous and condensed phases, measured by probe sampling and chemical analysis, indicated that pyrolytic routes leading to higher soot formation are more favoured in the lower temperature conditions. The structural analysis of condensed phases, including condensed species and soot, has been carried out by using FT-IR and UV-Visible spectroscopy sensitive to the hydrogen bonding and carbon network, respectively. The very low hydrogenated character, as evaluated by FT-IR and elemental analysis, and the high aromatic/graphitic nature of the benzene soot, as shown by a detailed examination of UV-Visible spectral parameters, confirmed the effect of benzene fuel on the internal structure of soot particles already in the early stages of particle inception. (C) 2012 The Combustion Institute. Published by Elsevier Inc. All rights reserved.