Particle size distribution of nascent soot in lightly and heavily sooting premixed ethylene flames

Gu, Chen; Lin, He; Camacho, J.J.; Lin, Baiyang; Shao, Can; Li, Ruoxin; Gu, Hao; Guan, Bin; Huang, Zhen; Wang, Shuangfeng

doi:10.1016/j.combustflame.2015.12.002

Cited by 69 publications

(41 citation statements)

References 60 publications

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“…[139]. The initial soot nuclei diameter is the smallest size identified in the inception peak of laminar premixed ethylene flames [4,117], a typical nuclei diameter in modelling soot dynamics [115] and rather insensitive to the employed equivalence ratios [140] for all soot volume fractions here. The number density of the soot surface radicals, χ s , in each soot particle is obtained using a steady state description for the radicals on the soot surface [3,129] During coagulation, every collision between particles is successful and leads to formation of either a sphere (full coalescence) or a cluster (agglomeration).…”

Section: Soot Aggregate or Agglomerate Characterization By Scaling Lawsmentioning

confidence: 82%

Flame synthesis of functional nanostructured materials and devices: Surface growth and aggregation

Kelesidis

Goudeli

Pratsinis

2017

Proceedings of the Combustion Institute

141

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Combustion is essential to the manufacture of carbon black, fumed oxides, optical fibers and, recently, new high-value products like carbon nanotubes, nanosilver and biomagnetic nanofluids that are driven to market predominantly by startups. This technology is attractive for material synthesis for its proven scalability as it does not involve the tedious steps of wet chemistry and can readily form stably metastable compositions and high purity products. Recent advances in aerosol and combustion sciences reveal that coagulation and sintering and/or surface growth control product particle size and morphology through the high temperature particle residence time, self-preserving size distribution and power laws for fractal-like particles. This motivates synthesis of an array of unique particle compositions and morphologies primarily by spray combustion leading to new catalysts, gas sensors and bio-materials and, most recently, to hand-held devices such as breath analysis sensors for monitoring chronic illnesses. In particular, multi-scale process design integrating mesoscale and molecular dynamics facilitates understanding of combustion product development. The latter contributes also to understanding of aggregation and surface growth of nascent soot, a bona fide nanostructured material! So here nascent soot dynamics, after nucleation or inception, are investigated through accounting of soot agglomeration and surface growth by acetylene pyrolysis. Neglecting the fractal-like nature of soot underestimates its mobility diameter and polydispersity up to 40%. The evolution of nascent soot structure from spheres to aggregates is quantified by the mass fractal dimension and mass-mobility exponent, in excellent agreement with microscopic and mass-mobility measurements in a standard burner-stabilized stagnation ethylene flame. Surface growth chemically bonds the constituent primary particles of these aggregates, while the effect of soot volume fraction on soot morphology is elucidated. Based on aggregate projected area, a scaling law is derived for determining the primary particle size of nascent soot aggregates from mass-mobility measurements rather than tedious image counting.

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Section: Soot Aggregate or Agglomerate Characterization By Scaling Lawsmentioning

confidence: 82%

Flame synthesis of functional nanostructured materials and devices: Surface growth and aggregation

Kelesidis

Goudeli

Pratsinis

2017

Proceedings of the Combustion Institute

141

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“…Available experimental techniques for measuring soot particle size and concentration have been discussed by Wang (2011), Desgroux et al (2013), Michelsen (2016), andD'Anna (2009). A series of experimental investigations of the particle size distribution function (PSDF) of soot particles formed in rich premixed ethylene flames have recently been conducted by Wang and co-workers Zhao et al 2003;Abid et al 2008;Camacho et al 2015;Gu et al 2016), Maricq et al (2003), and Stirn et al (2009). These studies first rely on the online sampling of the particles by a tubular probe placed transversally to the flame embedded or not in the stabilization plate or by a microprobe inserted vertically along the flame axis.…”

Section: Introductionmentioning

confidence: 99%

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

Betrancourt

Liu

Desgroux

et al. 2017

Aerosol Science and Technology

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(2017) Investigation of the size of the incandescent incipient soot particles in premixed sooting and nucleation flames of nbutane using LII, HIM, and 1 nm-SMPS, Aerosol Science and Technology, 51:8, 916-935, DOI: 10.1080/02786826.2017 Laser-induced incandescence (LII) measurements were conducted to explore the ability of LII to detect small soot particles of less than 10 nm in two sooting flat premixed flames of n-butane: a socalled nucleation flame obtained at a threshold equivalence ratio F D 1.75, in which the incipient soot particles undergo only minor soot surface growth along the flame, and a more sooting flame at F D 1.95. Size measurements were obtained by modeling the time-resolved LII signals detected using 1064 nm laser excitation. Spectrally-resolved LII signals collected in the nucleation flame display a similar blackbody-like behavior as mature soot. Soot particle temperature was determined from spectrally-resolved detection. LII modeling was conducted using parameters either relevant to those of mature soot or derived from fitting the modeled results to the experimental LII data. Particle size measurements were also carried out using (1) ex situ analysis by helium-ion microscopy (HIM) of particles sampled thermophoretically and (2) online size distribution analysis of microprobe-sampled particles using a 1 nm-SMPS. The size distributions of the incipient soot particles, found in the nucleation flame and in the early soot region of the F D 1.95 flame, derived from time-resolved LII signals are in good agreement with HIM and 1 nm-SMPS measurements and are in the range of 2-4 nm. The thermal and optical properties of incipient soot were found to be not radically different from those of mature soot commonly used in LII modeling. This explains the ability of incipient soot particles to produce continuous thermal emissions in the visible spectrum. This study demonstrates that LII is a promising in situ optical particle sizing technique that is capable of detecting incipient soot as small as about 2.5 nm and potentially 2 nm and resolving small changes in soot sizes below 10 nm.

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“…Ethylene (C 2 H 4 ) is often used as fuel for these studies because 1D ethylene/air flames can be obtained at high , where considerable amounts of soot are formed. Soot inception, volume fraction, surface growth, and particle size distribution [6][7][8][9][10][11][12][13][14][15][16] in ethylene flames have been studied extensively using both in situ and ex situ methods. However, since the measured soot volume fractions for premixed flames with identical equivalence ratios show significant variation, even when the measurement techniques are similar [17], it is hard to compare measurements from different studies quantitatively.…”

Section: Journal Of Combustionmentioning

confidence: 99%

“…The majority of the aforementioned studies did not investigate the effect of flame temperature independently from equivalence ratio; a change in is usually accompanied by a change in flame temperature. Notable exceptions are the studies of Ciajolo et al [6] and Gu et al [7] who studied the influence of temperature at fixed on soot volume fraction and particle size distribution, respectively, using physical sampling techniques. To our knowledge, only Böhm et al [8], Bönig et al [9], and Chambrion et al [10] have investigated the influence of flame temperature on soot formation in premixed C 2 H 4 /air flames at constant using noninvasive optical methods.…”

Section: Journal Of Combustionmentioning

confidence: 99%

“…were measured by spontaneous Raman spectroscopy, using the setup and method described in [29], utilizing the Stokes vibrational bands of N 2 , which are fairly well separated from the excitation laser line (∼2300 cm −1 ). For the experiments described here, deriving temperatures by fitting the acquired Raman spectra is complicated in progressively richer flames because it becomes increasingly difficult to distinguish the weak spontaneous Raman signal from the background signals from of soot radiation and Rayleigh scattering, which 1.0×10 6 1.5×10 6 1.3×10 7 1.4×10 7 1.4×10 7 1.5×10 7 1.5×10 7 1.6×10 7 1. is not completely eliminated by the filter/spectrometer combination. Raman thermometry could be used to determine temperatures of flames with equivalence ratios up to about = 2.1, depending on the exit velocity of the ethylene/air mixture.…”

Section: Raman Temperature Measurements Flame Temperaturesmentioning

confidence: 99%

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Growth of Soot Volume Fraction and Aggregate Size in 1D Premixed C₂H₄/Air Flames Studied by Laser-Induced Incandescence and Angle-Dependent Light Scattering

Langenkamp

Oijen

Levinsky

et al. 2018

Journal of Combustion

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The growth of soot volume fraction and aggregate size was studied in burner-stabilized premixed C2H4/air flames with equivalence ratios between 2.0 and 2.35 as function of height above the burner using laser-induced incandescence (LII) to measure soot volume fractions and angle-dependent light scattering (ADLS) to measure corresponding aggregate sizes. Flame temperatures were varied at fixed equivalence ratio by changing the exit velocity of the unburned gas mixture. Temperatures were measured using spontaneous Raman scattering in flames with equivalence ratios up to ϕ = 2.1, with results showing good correspondence (within 50 K) with temperatures calculated using the San Diego mechanism. Both the soot volume fraction and radius of gyration strongly increase in richer flames. Furthermore, both show a nonmonotonic dependence on flame temperature, with a maximum occurring at ~1675 K for the volume fraction and ~1700 K for the radius of gyration. The measurement results were compared with calculations using two different semiempirical two-equation models of soot formation. Numerical calculations using both mechanisms substantially overpredict the measured soot volume fractions, although the models do better in richer flames. The model accounting for particle coagulation overpredicts the measured radii of gyration substantially for all equivalence ratios, although the calculated values improve at ϕ = 2.35.

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Particle size distribution of nascent soot in lightly and heavily sooting premixed ethylene flames

Cited by 69 publications

References 60 publications

Flame synthesis of functional nanostructured materials and devices: Surface growth and aggregation

Flame synthesis of functional nanostructured materials and devices: Surface growth and aggregation

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

Growth of Soot Volume Fraction and Aggregate Size in 1D Premixed C₂H₄/Air Flames Studied by Laser-Induced Incandescence and Angle-Dependent Light Scattering

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Particle size distribution of nascent soot in lightly and heavily sooting premixed ethylene flames

Cited by 69 publications

References 60 publications

Flame synthesis of functional nanostructured materials and devices: Surface growth and aggregation

Flame synthesis of functional nanostructured materials and devices: Surface growth and aggregation

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

Growth of Soot Volume Fraction and Aggregate Size in 1D Premixed C2H4/Air Flames Studied by Laser-Induced Incandescence and Angle-Dependent Light Scattering

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Growth of Soot Volume Fraction and Aggregate Size in 1D Premixed C₂H₄/Air Flames Studied by Laser-Induced Incandescence and Angle-Dependent Light Scattering