Soot aggregate morphology in coflow laminar ethylene diffusion flames at elevated pressures

Gigone, Ben; Karataş, Ahmet E.; Gülder, Ömer L.

doi:10.1016/j.proci.2018.06.103

Cited by 33 publications

(12 citation statements)

References 45 publications

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“…̅̅̅ increases with pressure up to 4 atm and changing pressure from 4 to 5 atm, does not change ̅̅̅ significantly. These trends are consistent with the ones obtained from ethylene flames (Gigone et al, 2019, Steinmetz et al, 2016 but contradicts with the pressurized flames of methane (Vargas and Gülder, 2016).…”

Section: Resultssupporting

confidence: 86%

Investigating Soot Parameters in an Ethane/Air Counterflow Diffusion Flame at Elevated Pressures

Amin

Roberts

2020

Combustion Science and Technology

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Soot emissions from diesel engines and gas turbines are influenced by the combustion environment. Pressure is one of the parameters which affects particulate emissions and these effects are poorly understood on soot parameters. In this work, pressurized counterflow diffusion flame of ethane and air has been investigated using two angle light scattering and extinction technique. A counterflow diffusion flame has been stabilized from 2 to 5 atm in a pressure vessel which can provide optical access from 10 to 165° in angular direction. Global strain rate (a) of 30 s-1 is maintained at all pressures by adjusting the inlet flows. Scattering measurements are performed at two angles (45° and 135°) and Rayleigh-Debye-Gans theory for Fractal Aggregates (RDG-FA) has been used to determine soot parameters from light scattering and extinction data. By combining the scattering at 135° with laser extinction measurements, path averaged soot volume fraction (fv), mean primary particle diameter (̅̅̅) and particle number densities (np), along the axis of the counterflow flame are calculated. Local soot volume fraction (fv,local) profiles are also measured using diffuse light 2D line of sight attenuation technique. Peak value of fv increases from 0.3 ppm to 8 ppm as the pressure is raised from 2 to 5 atm. Primary particle size (̅̅̅) also increases with pressure where peak primary particle size of 11 nm at 2 atm rises to 38 nm at 5 atm. Population average radius of gyration (Rg) increases with pressure while the number densities (np) of primary particles decrease due to coalescence.

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Section: Resultssupporting

confidence: 86%

Investigating Soot Parameters in an Ethane/Air Counterflow Diffusion Flame at Elevated Pressures

Amin

Roberts

2020

Combustion Science and Technology

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“…The average diameter of primary particles along the flame wing is larger than those along the flame centerline, which is different from the distributions of particle number density, as described in our previous work. 3 In addition, the average diameter ranges from 15 to 65 nm for most particles, which is similar to the measured results of Gigone et al 17 by transmission electron microscopy observations. An increase in overall particle sizes with the increase of pressure is displayed, and the average diameters of the particles in the wing of the flame increase faster than those in the centerline, similar to the trend of Steinmetz et al 18 According to Choi et al, 45 the density of solid soot particles is assumed to be 1.8 g/cm 3 in the present work, and the primary particle is assumed be spherical, hence the primary diameter is only concerned with its mass.…”

Section: Effects Of Pressure Onsupporting

confidence: 89%

“…11 Nevertheless, the ambient pressure of in-cylinder combustion is much higher, which has significant effects on the overall soot yield as well as the rates of soot reactions. 16 Gigone et al 17 measured the particle morphological characteristics in a laminar ethylene flame at elevated pressures, and the results showed that the average diameter of primary soot particle, particle number density, and fractal dimension increase with increasing pressure. Steinmetz et al 18 investigated the particle size in laminar ethylene coflow flames at elevated pressures by laser scattering, and found that the particle sizes in the flame wing rise faster than those along the centerline with the increase of pressure.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Soot Formation in a Methane Diffusion Flame Doped with n-Heptane at Elevated Pressure

et al. 2019

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Combustion characteristics are significantly affected by ambient pressure, which is usually much higher than the atmosphere in the engine cylinder. In this work, the effects of pressure on the flame structure and soot behavior in a methane diffusion flame doped with n-heptane were numerically investigated by a detailed chemical mechanism and a sectional soot model. The results show that the high-temperature region moves toward the wings of flame and the radius of the flame decreases as ambient pressure increases. Soot volume fraction increases significantly with its peak value scaled with p 2.25 for the pure methane flame and p 1.60 for the methane flame doped with n-heptane. In addition, the height at which the initial soot forms moves upstream, while the height at which soot particles are completely oxidized moves downstream, resulting in a larger sooting region. The increase of soot concentration is mainly due to the increase of the mixture density as pressure changes, and therefore, the collision frequency between gas species and particles increases, which in turn accelerates the inception rate and surface growth rate of particles. Primary number density also increases because of the increase in the inception rate. The aggregate characteristics, which are evaluated by the number of primary particles per aggregate, increase because of the increase in the particle number density that leads to an acceleration in particle coagulation. Soot mass addition, dominated by hydrogen-abstraction–carbon-addition reactions, increases because of the increase of absolute concentrations of C2H2 and H radicals, while soot mass consumption, dominated by OH oxidation, increases with a lower rate than that of soot addition because of the increase of the collision frequency and efficiency between the OH radicals and particles.

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“…In this post-flame zone, soot particles are largely oxidized by the excess air. This might explain why the diameter of primary soot particles emitted by commercial aircraft engines is found relatively small around 15-16 nm on a large range of engine thrusts [34,35] by contrast to the much larger diameter of soot particles sampled in the sooting zone of high pressure combustors [36]. In the next section, we evaluate whether the exposure of soot particles to OH radicals, present between the combustor and the exit of an aeronautic engine, could be high enough to make them sufficiently active to become CCNs.…”

Section: Comparison Between Kerosene and Diesel Sootmentioning

confidence: 99%

Hydrophilic properties of soot particles exposed to OH radicals: A possible new mechanism involved in the contrail formation

Grimonprez

Faccinetto

et al. 2021

Proceedings of the Combustion Institute

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Soot aggregate morphology in coflow laminar ethylene diffusion flames at elevated pressures

Cited by 33 publications

References 45 publications

Investigating Soot Parameters in an Ethane/Air Counterflow Diffusion Flame at Elevated Pressures

Investigating Soot Parameters in an Ethane/Air Counterflow Diffusion Flame at Elevated Pressures

Numerical Investigation of Soot Formation in a Methane Diffusion Flame Doped with n-Heptane at Elevated Pressure

Hydrophilic properties of soot particles exposed to OH radicals: A possible new mechanism involved in the contrail formation

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