Nano-organic carbon and soot particle measurements in a laminar ethylene diffusion flame

Structure of incipiently sooting ethylene–nitrogen counterflow diffusion flames at high pressures

“…Perhaps indene, the largest species quantified may be considered a marker for soot formation since its peak mole fraction value increases very significantly at the highest pressure level in each series, when soot becomes visible (incipient sooting condition). Generally, there is a clear positive correlation between aromatic production and soot formation, confirming the abundant literature showing, for example, that broad visible fluorescence peaks, typically attributed to PAHs, precede the location where soot is detected [19], a trend confirmed more recently by more detailed fluorescence measurements in the UV [18]. The correlation was also observed in high pressure studies in [23], but since coflow flames are controlled by buoyancy, whose intensity increases with density, the residence time along the centerline of the coflow flames might have changed, adding to the pressure effect to an unknown extent.…”

“…Optical techniques aimed to quantify soot volume fraction (LII [16,17]), absorption/scattering [18]), and PAH fluorescence [19] suffer from severe beam steering through density gradients. The thin reacting environments at high pressures because of the low thermal and mass diffusivity makes probe-based studies more difficult to implement.…”

Investigation of the size of the incandescent incipient soot particles in premixed sooting and nucleation flames of n-butane using LII, HIM, and 1 nm-SMPS

“…Very recently, Tang et al (2016) have demonstrated that incipient soot particles as small as about 1.5 nm can be measured with a diethylene glycol (DEG) SMPS. It is noticed that Sgro et al (2007) and D'Anna et al (2005 also measured particles with sizes below 2 nm in rich premixed and diffusion flames; however, they considered these particles as a new category of flame-generated nanostructure, namely nanoparticles of organic carbon (NOC), rather than newly formed incipient soot particles.…”

“…Nevertheless, signals could be detected in the nucleation region of a laminar coflow diffusion flame by D' Anna et al (2005), from which mean particle diameters of about 3 to 4 nm were determined. The particles detected by D'Alessio and coworkers were referred as NOC (Sgro et al 2007(Sgro et al , 2009D'Anna et al 2005). Besides the needs to correct the scattering signals due to large gas-phase compounds (D'Anna 2009), the scattering signals tend to be dominated by the presence of a few large particles, e.g., aggregates (Zhao et al 2003).…”

A comparative study of nanoparticles in premixed flames by scanning mobility particle sizer, small angle neutron scattering, and transmission electron microscopy

“…In only rare cases, particles <10 nm were observed [12,17,24]. While the cause remains unclear, explanations have been advanced that ranged from small thermophoretic sampling efficiencies for particles <10 nm [25], the transparent nature of these particles to an electron beam [12,17], to misrepresentation of the mobility data by SMPS [26]. To clarify the cause for this discrepancy, we carried out comparative SMPS and TEM studies on two different types of particles, namely soot particles in the ethylene flame and inorganic TiO 2 particles produced in a premixed stagnation flame, using the same sampling and analysis techniques.…”