The atmospheric effects of soot aerosols include interference with radiative transfer, visibility impairment, and alteration of cloud formation and are highly sensitive to the manner by which soot is internally mixed with other aerosol constituents. We present experimental studies to show that soot particles acquire a large mass fraction of sulfuric acid during atmospheric aging, considerably a...

Soot formation was studied within laminar premixed ethylene/air flames (C/O ratios of 0.78-0.98) stabilized on a flat-flame burner operating at atmospheric pressure. Measurements included soot volume fractions by both laser extinction and gravimetric methods, temperatures by multiline emission, soot structure by thermophoretic sampling and transmission electron microscopy, major gas species con...

In this article, we present a new database of thermodynamic properties for polycyclic aromatic hydrocarbons (PAH). These large aromatic species are formed in very rich premixed flames and in diffusion flames as part of the gas-phase chemistry. PAH are commonly assumed to be the intermediates leading to soot formation. Therefore, accurate prediction of their thermodynamic properties is required ...

Planar laser-induced incandescence (LII) imaging is reported at repetition rates up to 100 kHz using a burst-mode laser system to enable studies of soot formation dynamics in highly turbulent flames. To quantify the accuracy and uncertainty of relative soot volume fraction measurements, the temporal evolution of the LII field in laminar and turbulent flames is examined at various laser operatin...

The in uence of fuel chemical composition on  ame structure and sooting trends in a swirling spray  ame was investigated semiquantitatively using a light-scattering/dissymmetry ratio technique. Binary mixtures of toluene and methanol were examined under Ž xed aerodynamic and burner inlet  ow conditions to show the effect of liquid composition. The sprays were generated using an air-assist a...

Personnel involved: Prof. Jack B. Howard, PI. Department of Chemical Engineering, MIT Dr. Henning Richter, Research Associate, Department of Chemical Engineering, MIT Murray J. Height, Graduate Student, Department of Chemical Engineering, MIT Timothy G. Benish, Graduate Student, Department of Chemical Engineering, MIT Dr. Peter Hebgen, Postdoctoral Associate, Department of Chemical Engineering,...

The generation by combustion processes of airborne species of current health concern such as polycyclic aromatic hydrocarbons (PAH) and soot particles necessitates a detailed understanding of chemical reaction pathways responsible for their formation. The present review discusses a general scheme of PAH formation and sequential growth of PAH by reactions with stable and radical species, includi...

Wildfires contribute significantly to global soot emissions, yet their aerosol formation mechanisms and resulting particle properties are poorly understood and parameterized in climate models. The conventional view holds that soot is formed via the cluster-dilute aggregation mechanism in wildfires and emitted as aggregates with fractal dimension Df ≈ 1.8 mobility diameter Dm ≤ 1 μm, and aerodyn...

Experimental observations of the combustion of sooting fuel droplets, performed in a drop tower to create a low gravity environment, are reported. Free n-heptane droplets and suspended droplets of heptane. monochloroalkanes. and mixtures of monochloro-octane and heptane were studied. Initial droplet diameters ranged from 0.4 to I. 1 mm. The results suggest that soot may influence droplet vapori...

A new method is described for large-scale production of Single Wall Carbon Nanohorns (SWCNH). In a prototype reactor (a 30 kW plant for an estimated production of about 100 g/h of soot) optimal thermodynamic conditions that favour nanohorn formation were determined. The characterization of collected soot was performed by several techniques: thermogravimetric analyses (TGA), Raman spectroscopy, ...