Measurement of nanoparticles of organic carbon in non-sooting flame conditions

Sgro, Lee Anne; Barone, A.; Commodo, Mario; D’Alessio, Antonio; Filippo, Andréa; Lanzuolo, G.; Minutolo, P.

doi:10.1016/j.proci.2008.06.216

Cited by 76 publications

(70 citation statements)

References 32 publications

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“…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).…”

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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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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“…Most of the flames burned mixtures of ethylene and air, but one hotter flame was also studied that utilized Ar as the oxygen diluent rather than N 2 . Previous works showed that these flames, which produce significant amounts of particles with diameters of just a few nanometers, are below the onset of soot particles since they have undetectable amounts of absorption in the visible or incandescence Minutolo et al 1998;Sgro et al 2009). The sampling probe is a tube (ID = 8 mm) positioned horizontally over the flame.…”

Section: Experimental Methodsmentioning

confidence: 99%

“…We verified that losses are negligible by comparing the size distribution function measured with the TapCon DMA without loss correction to the one measured with the TSI instrument with loss correction. Since the TapCon DMA measured comparable or higher values, we did not correct measurements made with the TapCon DMA for particle losses within the DMA itself as in earlier works Sgro et al 2009;Sgro et al 2007). …”

Section: Experimental Methodsmentioning

confidence: 99%

“…Losses are only significant in the orifice prior to dilution and only for d < 4 nm particles Sgro et al 2009). Previous works investigating the impact of flame-generated inception particles with surfaces at flame temperatures concluded that d < 5 nm particles may experience thermal rebound, and there is no currently accepted theory to calculate size-dependent losses of particles in tubes at the temperature of the orifice (800-1000 K) in the size range of interest in this study (1-5 nm) (D'Alessio et al 2005;De Filippo et al 2009;Sgro et al 2009). Losses in the orifice are significantly different depending on whether or not thermal rebound occurs, but in both cases they only affect d < 4 nm particles (see Figure 5 in De Filippo et al 2009).…”

Section: Experimental Methodsmentioning

confidence: 99%

“…While the various measurement techniques are in excellent agreement in flame conditions that eventually produce particles larger than 3-5 nm, the DMA measurements are significantly lower than in situ optical measurements in flame conditions where the size distribution is unimodal with a modal diameter, d modal ∼ 2 nm ). The reason for this discrepancy, which cannot be explained simply as losses in the sample lines, is not yet well understood because of the inherent uncertainties of the measurement techniques (Minutolo et al 2007;Sgro et al 2009). A side objective of this work is also to verify if the assumed charging efficiency of the particle charger used in the DMA data analysis could be inaccurate for the smallest inception particles resulting in a source of experimental error.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Charge Distribution of Incipient Flame-Generated Particles

Sgro

D’Anna

Minutolo

2010

Aerosol Science and Technology

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We report the size and electrical charge distributions of incipient nanoparticles generated in atmospheric pressure hydrocarbon/air premixed flames in conditions prior to the onset of soot particles. The particle size and charge distributions are measured by Differential Mobility Analysis (DMA) and compared to theoretical charge distributions predicted for flame conditions. The results show that the charge distribution attained in flames is well predicted by Boltzmann theory for all particles, including even the smallest incipient particles with diameters in the 1-3 nm size range. In flame conditions that produce only particles smaller than 3 nm, the charge fraction of particles agrees with that predicted by Boltzmann theory near the flame temperature (1700 K). In flame conditions with 'bimodal' particle size distributions, the charge fraction of the smallest particles agrees with the Boltzmann prediction at maximum flame temperature, while the charge fractions of larger particles agree with Boltzmann theory at temperatures that coincide with the local temperature near the probe surface (1000-1200 K). The results of this paper show that the temperature of the Boltzmann charge fraction that best agrees with the measured charge fraction for each particle size gives the local temperature of their last coagulation event. The smaller particles, which retain their charge fraction predicted by Boltzmann at the maximum flame temperature, do not thermalize by coagulation in the cool region near the probe evidencing low probability for charge transfer as well as for coagulation.

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Ultrafast Fluorescence Anisotropy for Combustion‐Produced Nanoparticles Analysis

Bruno

Lisio

Minutolo

2010

Handbook of Combustion

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Understanding the formation mechanism of particulate matter due to incomplete combustion is fundamental to controlling the atmospheric impact of combustion systems. Toxicological studies have demonstrated that ultrafine aerosols can penetrate deep into the pulmonary alveoli, and affect human health. Different studies have identified in rich premixed flames a variety of carbon nanoparticles, ranging from those smaller than 3 nm (defined as nanoparticles of organic carbon, NOC) to larger soot particles of 20 nm, and more for aggregates. Optical methods represent the most desirable methods for nanoparticles studies, due to their accuracy, flexibility, and nonintrusive nature. Two principal uncertainties limit standard optical diagnostics in combustion systems: the spectroscopic properties of the NOC are similar to those of polycyclic aromatic hydrocarbons; and when light scattering is weak and comparable to that from gas‐phase compounds, size measurement is affected by large uncertainties. Thus, it is necessary to exploit certain properties of fluorescence, which will depend unambiguously upon the size of the nanoparticles. This goal is achieved by using time‐resolved fluorescence anisotropy (TRFA), which leads to both size and spectral characterization of the investigated particles. TRFA shows much promise, and is highly sensitive for detecting nanoparticles, even in a flame hostile environment. It also differs from other sizing methods such as light scattering, as it does not depend on the refractive index. Moreover, exploiting spectral selectivity in light excitation and emission information on chemical functionalities of nanoparticles can be deduced. TRFA opens up new possibilities for combustion and environmental monitoring of nanoparticles. In this chapter, the theory of TRFA ultrafast technique is derived for different operating conditions. Experimental realizations, results and the analysis of nanoparticles produced in flames in two different configurations (directly in flames and for samples collected from the flame) are then presented and discussed.

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Measurement of nanoparticles of organic carbon in non-sooting flame conditions

Cited by 76 publications

References 32 publications

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

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

Charge Distribution of Incipient Flame-Generated Particles

Ultrafast Fluorescence Anisotropy for Combustion‐Produced Nanoparticles Analysis

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