Influence of soot aggregate size and internal multiple scattering on LII signal and the absorption function variation with wavelength determined by the TEW-LII method

Yon, Jérôme; Therssen, E.; Liu, F.; Béjaoui, S.; Hébert, D.

doi:10.1007/s00340-015-6116-y

Cited by 16 publications

(23 citation statements)

References 39 publications

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“…E m 1064 ∕E m 532 = 1 yields the best agreement in soot volume fraction ratio between LII and CRDE measurements at HAB = 10 mm in the two flames. The absence of significant variation of E(m ) between 532 and 1064 nm for soot particles of different maturities is consistent with observations by [24,[34][35][36]. It contrasts with the previous work of Cleon et al which reports a 30% decrease of E(m 532 )∕E(m 1064 ) from incipient soot to mature soot in a premixed low pressure flame [54].…”

Section: Assumption 2: E(m λEm ) Is Dependent On Both Wavelength and supporting

confidence: 86%

“…It is inspired by previous methods reported in the literature that rely on the behavior of LII signal with the laser fluence (fluence curve) to extract in situ information on some physical-chemical parameters of soot. Among these methods, the two-excitation wavelength LII technique, first introduced by Therssen et al [33] has been applied to determine the relative spectral variation of the absorption function of soot particles of different maturities in various flames [25,[33][34][35][36]. The method relies on producing identical time-resolved and spectrally resolved LII signals, i.e., identical soot temperature, by adjusting the laser fluence of one of the two lasers of different wavelengths.…”

Section: Introductionmentioning

confidence: 99%

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Quantitative measurement of volume fraction profiles of soot of different maturities in premixed flames by extinction-calibrated laser-induced incandescence

et al. 2019

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The laser-induced incandescence (LII) and cavity ring-down extinction (CRDE) optical techniques offer excellent sensitivity to allow in situ soot volume fraction (f v) measurements over a wide dynamic range. The objective of this work is to quantitatively measure the axial f v profiles in two n-butane premixed flames with very different stages of soot maturity and very different levels of f v. The first flame is a nucleation flame in which soot particles undergo only minor growth and have diameters between 2 and 4 nm. The second is a normal sooting flame generating soot from inception to mature stage. Experiments were performed by combining LII and CRDE using a laser at 1064 nm. Quantitative measurements of f v require the knowledge of the dependence of soot absorption function E(m) on wavelength and soot maturity. To this aim, two novel approaches were developed to evaluate the variation of E(m) at 1064 nm along the flame centerline and between 532 and 1064 nm covering the entire spectral range used in this study. The axial LII profiles were converted to absolute f v by CRDE measurements. The performance of the combined techniques is demonstrated in the two investigated flames for f v in the range of 0.013-9.7 ppb. This article is part of the topical collection "Laser-Induced Incandescence", guest edited by Klaus Peter Geigle and Stefan Will. C. Betrancourt: on leave from Univ. Lille.

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Section: Assumption 2: E(m λEm ) Is Dependent On Both Wavelength and supporting

confidence: 86%

Section: Introductionmentioning

confidence: 99%

Quantitative measurement of volume fraction profiles of soot of different maturities in premixed flames by extinction-calibrated laser-induced incandescence

et al. 2019

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“…The values of C i (A e ) were determined by performing a non-linear least-squares fit to the measured LII temporal profiles. We neglected the effects of aggregate size and morphology on the LII signal because the absorption cross section, and hence radiative-emission rates, are predicted to be nearly independent of such effects over the detection wavelength range and aggregate sizes studied (Mackowski, 2006;Yon et al, 2014Yon et al, , 2015 3.1.3. LII signal on the scatter channel Figure 3b shows the spectral response of the APD (i.e., for the scatter channel), the transmittance of the optical filter for this channel, and their product R λScat .…”

Section: Signal Calculationmentioning

confidence: 99%

Effects of aggregate morphology and size on laser-induced incandescence and scattering from black carbon (mature soot)

Bambha

Michelsen

2015

Journal of Aerosol Science

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a b s t r a c tWe have used a Single-Particle Soot Photometer (SP2) to measure time-resolved laserinduced incandescence (LII) and laser scatter from combustion-generated mature soot with a fractal dimension of 1.88 extracted from a burner. We have also made measurements on restructured mature-soot particles with a fractal dimension of 2.3-2.4. We reproduced the LII and laser-scatter temporal profiles with an energy-and mass-balance model, which accounted for heating of particles passed through a CW-laser beam over laser-particle interaction times of $ 10 μs. The results demonstrate a strong influence of aggregate size and morphology on LII and scattering signals. Conductive cooling competes with absorptive heating on these time scales; the effects are reduced with increasing aggregate size and fractal dimension. These effects can lead to a significant delay in the onset of the LII signal and may explain an apparent low bias in the SP2 measurements for small particle sizes, particularly for fresh, mature soot. The results also reveal significant perturbations to the measured scattering signal from LII interference and suggest rapid expansion of the aggregates during sublimation.

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“…222 Hence the maturity level of a soot particle describes how much it has evolved from inception towards a fully mature graphite-like particle. 20,22,84,204,[223][224][225][226][227][228][229][230][231][232] The surface of the particle can have a different maturity level from that of the bulk. 22,225,226 Young soot particles: Young soot particles are those in an early stage of development between inception and full maturity.…”

Section: Maturity and Maturity Levelmentioning

confidence: 99%

“…226 These characteristics are predominantly defined by the particle's fine structure, which is described as being polycrystalline turbostratic graphite with coherent domains (crystallite regions without major defects or dislocations) slightly larger than 1 nm in diameter and 4-5 layers in thickness with an interlayer spacing of 0.34-0.35 nm. 20,22,84,113,138,141,186,226,229,231,232,[239][240][241] Mature soot particles also tend to be strongly bound into ramiform aggregates of monodisperse primary particles. 132,[242][243][244][245] For combustion conditions near the sooting threshold, however, primary-particle monomers with diameters as small as 2-3 nm and optical properties consistent with mature soot have been observed.…”

Section: Maturity and Maturity Levelmentioning

confidence: 99%

A Review of Terminology Used to Describe Soot Formation and Evolution under Combustion and Pyrolytic Conditions

Colket²,

et al. 2020

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This paper presents a glossary and review of terminology used to describe the chemical and physical processes involved in soot formation and evolution. This review is intended to aid in communication within the field and across disciplines. There are large gaps in our understanding of soot formation and evolution and inconsistencies in the language used to describe the associated mechanisms. These inconsistencies lead to confusion within the field and hinder progress in addressing the gaps in our understanding. This review provides a list of definitions of terms and presents a description of their historical usage. It also addresses the inconsistencies in the use of terminology in order to dispel confusion and facilitate the advancement of our understanding of soot chemistry and particle characteristics. The intended audience includes senior and junior members of the soot, black-carbon, brown-carbon, and carbon-black scientific communities, researchers new to the field, and scientists and engineers in associated fields with an interest in carbonaceous-material production via high-temperature hydrocarbon chemistry.

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Influence of soot aggregate size and internal multiple scattering on LII signal and the absorption function variation with wavelength determined by the TEW-LII method

Cited by 16 publications

References 39 publications

Quantitative measurement of volume fraction profiles of soot of different maturities in premixed flames by extinction-calibrated laser-induced incandescence

Quantitative measurement of volume fraction profiles of soot of different maturities in premixed flames by extinction-calibrated laser-induced incandescence

Effects of aggregate morphology and size on laser-induced incandescence and scattering from black carbon (mature soot)

A Review of Terminology Used to Describe Soot Formation and Evolution under Combustion and Pyrolytic Conditions

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