Soot Formation in Premixed Hydrocarbon Flames

Abstract

The critical fuel‐oxygen ratio for soot formation and its dependence on temperature and pressure are discussed for various hydrocarbons. It is shown in the case of the Bunsen flame that the shape and structure of the flame front also have a decisive effect on soot formation. In the reaction zone of fuel‐rich hydrocarbon flames, unsaturated compounds are formed, and the concentration profiles of these products can provide quantitative information about their importance in soot formation. The “mechanism” of soot formation is discussed on the basis of the concentrations of higher hydrocarbons and the variation of the number and size of the soot particles. The effects of electric fields and foreign additives on soot formation have been given consideration.

Nanostructuration of carbonaceous dust as seen through the positions of the 6.2 and 7.7μm AIBs

“…A driving force between these scenarios is the role of chemical condensation, as opposed to physical condensation, which involves pure van der Waals forces for the formation of the PAH clusters. Experimental evidences for the implication of reactivity between the molecules that compose the carbonaceous precursors (chains or PAHs) are more and more observed and predicted (Homann 1998;Violi et al 2005;Chung & Violi 2011). Actually, the scenarios that dominate the combustion literature all involve PAHs, but have been recently rationalized into two main paths.…”

“…These polyaromatic unit sizes are of a few nanometers maximum (Vander Wal et al 2007;Alfè et al 2009) and are generally linked by an aliphatic component. The organised domains range from two to, typically, four stacked graphene layers (bi-periodic turbostratic order) that could be regarded as highly disordered graphitic lattices (Bockhorn 1994;Homann 1998;Dippel et al 1999;Sadezky et al 2005;Alfè et al 2009). These stacked polyaromatic units form the basic structural units, the BSUs.…”

The 6.2 $\sf \mu{\rm m}$ band position in laboratory and astrophysical spectra: a tracer of the aliphatic to aromatic evolution of interstellar carbonaceous dust

“…This type of flame is considered as a model system for the physical and chemical study of combustion processes. It displays the peculiar property of offering a onedimensional reactor where the axis normal to the plane of the burner is in fact directly linked to the chemical evolution time (Bockhorn 1994;Homann 1998;D'Anna et al 2000;Richter & Howard 2000). Such a reactor has already been used in the context of cosmic dust analogue production but mainly for studies of the interstellar UV bump region (217 nm) in the spectra of soot samples (Schnaiter et al 1996).…”

“…Other than sooting flames other types of reactors have been used, such as: laser pyrolysis (Schnaiter et al 1999;Galvez et al 2002;Jäger et al 2006), photolysis (Dartois et al 2004), laser ablation (Mennella et al 1999), reactive plasmas (Lee & Wdowiak 1993;Scott & Duley 1996;Furton et al 1999;Goto et al 2000), etc. In most of these experiments the low pressure premixed flame was clearly shown to produce gas phase aromatic material in the size range of a few hundreds of carbon atoms (Homann 1998;Weilmünster et al 1999;Keller et al 2000;Fialkov et al 2001). With our setup we have investigated the possibility of producing such molecular assemblies as analogues of astrophysical hydrocarbons.…”

Nanostructuration of polyaromatic analogues of the carbonaceous dust

“…Other concepts may be used, the main one concerns the organisation of these polyaromatic units: the organised domains range from two to, typically, four stacked polyaromatic layers (Alfè et al 2009;Bockhorn 1994;Dippel et al 1999;Homann 1998;Sadezky et al 2005). These stacked polyaromatic units are forming the basic structural units, the BSUs.…”