A Shock-Tube and Modeling Study of Soot Formation During Pyrolysis of Propane, Propane/Toluene and Rich Propane/Oxygen Mixtures

Abstract

The authors studied soot formation during the pyrolysis of propane/Ar, propane/toluene/Ar, and rich propane/oxygen/Ar mixtures behind reflected shock waves. The time profiles of soot yield and temperature were obtained. The soot-suppressing effect of oxygen and soot-promoting effect of toluene were revealed. The results were simulated within the framework of a detailed kinetic model composed of 2760 direct and reverse elementary steps and involving 284 species. As compared to the authors’ previous studies, the model was refined and tested against experimental data on pyrolysis and oxidation of a number of hydrocarbons. The measured and calculated time profiles of soot yield and soot particle temperatures, as well as soot yield temperature dependences, for the tested mixtures were found to be in close agreement.

Keywords:

• Kinetic modeling
• Propane pyrolysis and oxidation
• Shock waves
• Soot formation
• Toluene additives

ACKNOWLEDGMENTS

This work was supported by the Russian Foundation for Basic Research, project no. 08-08-00722 and the Russia Federal Targeted Program “Research and Research-Human Resources for Innovating Russia,” project NK-576P.

Notes

^a Rate coefficients are presented in the form k = AT ^bexp(−Ea/RT).

^b Index n denotes the number of carbon atoms, which are incorporated into the particle in each act of interaction with carbon-containing gas-phase species. An * indicates that the rate coefficient was modified in the present work. Soot nuclei and soot particles with active sites on the surface are denoted as C[N] and S[N], respectively, and soot nuclei and soot particles without active sites are denoted as CH[N] and SH[N], respectively. Notation S[N], SH[N] means the concentration of soot particles after N acts of interaction with various carbon-containing gas-phase species (Agafonov et al., 2007; Appel et al., 2008; Richter et al., 2005).