Characterization of Soot Particles in Laminar Diffusion by Laser-induced Incandescence PDF Download

Author: Alexandre Dias Flügel
Publisher:
ISBN: 9783945806135
Category :
Languages : en
Pages :

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Author: Babak Borshanpour
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 52

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An investigation of soot formation in laminar diffusion flames has shown that soot particle surface growth under laminar diffusion flame conditions ceases because of the depletion of hydrocarbon species, in particular acetylene and benzene, and not due soot particle reactivity loss due to thermal aging of the particles. This results has been obtained through direct species concentration measurements under well controlled conditions while the particle reactivity effects were calculated based on premixed flame results along with particle temperature/time information available from earlier laminar diffusion flame studies. Comparisons with a soot formation model which incorporated detailed chemistry effects showed good agreement in terms of predicted and measured species concentration and soot particle field evolution. In addition, a novel technique for measuring soot volume fraction has been developed based on laser-induced incandescence and applied to similar laminar diffusion flame, studies with good success. This technique represents a major development in terms of its ability to make soot volume fraction measurements in unsteady inhomogeneous combusting flows. Soot formation, Soot particles, Diffusion flames.

Author: Sanaz Ghasemi
Publisher:
ISBN: 9780494851913
Category :
Languages : en
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Author: Cornelia Irimiea
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Combustion impacts many important aspects of our life like the air quality, the local and global climate and the use of energy sources. In the last decades, an outstanding progress towards cleaner combustion has been achieved. However, the reaction pathways leading to the formation of some pollutants, especially particulate matter (soot) resulting from incomplete combustion, are still elusive. In this work, we aim to investigate specific aspects of soot and its precursors formation in laboratory flames for a fundamental understanding of the mechanisms leading from the gas phase up to the mature particulate found in the exhausts. This objective is also pursued in field-campaigns to assess the potential impact of soot surface properties on the environment. Following this approach, experimental techniques like in-situ laser induced incandescence and fluorescence, and ex-situ laser desorption and secondary ion mass spectrometry are used to target specific properties of soot and its precursors. Notably, the evolution of the complex refractive index of soot is measured as a function of soot maturity, and the implications on both the flame physico-chemistry and the analytical techniques applicability are discussed. Additionally, a new detection method for soot and precursors based on simultaneous excitation at one wavelength is developed. In parallel, two campaigns are dedicated to the analysis of the surface chemistry of soot sampled from airplane and car exhausts. Statistical methods as multivariate analysis are used to identify patterns and differences within sets of samples by assessing the influence of the combustion parameters or the role of the fuel.

Author: Daniel Dennis Emile Cormier
Publisher:
ISBN: 9780494765098
Category :
Languages : en
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Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 78

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The focus of this AASERT grant was the development of two novel measurement approaches for soot property characterization: laser-induced incandescence and intrusive probe sampling of soot particles from diffusion flames. Characterization of the laser-induced incandescence technique for soot particle measurements in laminar diffusion flames resulted in the development of a new quantitative measurement technique for soot volume fraction and marked the first use of this technique for quantitative measurements. In particular, the relationship between laser fluence and the temporal character of the laser-induced incandescence signal was carefully examined and documented. Based on the laminar flame work, the technique was extended to soot particle measurements in turbulent diffusion, spray and droplet flames with similar quantitative results. Concurrently, an intrusive probe sampling system to collect soot particles from laminar diffusion flames was developed. This sampling system provided collection sample sizes up to 2 grams of soot. Large soot samples were required to allow for appropriate surface area characterization which was conducted using a BET measurement approach. jg p1.

Author: Thi Linh Dan Ngo
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

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Interest in biofuels has increased significantly in recent years as they could reduce dependence on fossil fuels and contribute to carbon-neutral growth. The influence of using biofuels on their exhaust emissions (CO,CO_2,NO_x,HC, etc.) has been studied widely. However, the effects of the nature of these alternative fuels on the physical and chemical properties of the particles and aromatic species produced are not fully understood. As part of this thesis work, we aim to study the emissions of soot particles and polycyclic aromatic hydrocarbons (PAHs) during the combustion of conventional and alternative fuels (biofuels) relevant to the automotive and aerospace sectors, while trying to highlight their influence on the formation of such pollutants. To achieve this goal, two laboratory combustors, a swirled turbulent jet burner and a Combustion Aerosol STandard (CAST), were used as soot generators. In addition, we have combined various complementary in-situ laser techniques, laser-induced incandescence and fluorescence (LII/LIF), and ex-situ two-step laser mass spectrometry (L2MS) and secondary ion mass spectrometry (SIMS). In a swirled turbulent jet flame for five fuels (Diesel, n-butanol, 50/50 Diesel/n-butanol mixture, Jet A1 and Synthetic Paraffinic Kerosene SPK), the LII and LIF profiles and properties of soot particles and their precursors with the height in the flame as well as their chemical composition were studied. Strong correlations between the results obtained with in-situ and ex-situ techniques have been demonstrated which allowed us to characterize these species spectrally and chemically. In addition, a new calibration method has been developed to directly deduce the soot volume fraction from the LII signal using the absolute radiance emitted from a light source having black body behavior. In parallel, experiments using the CAST device were conducted with aeronautical fuels (Jet A1 and SPK). In addition to the influence of the alternative fuel, the effects of a catalytic stripper (CS) on soot particles and volatile species were examined.

Author: Chung-Yuan Yin
Publisher:
ISBN:
Category :
Languages : en
Pages : 48

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Laser-induced incandescence (LII) is used to obtain soot particle size measurements in laminar premixed ethylene flames. The LII signals are calibrated by comparing with the particle diameters measured with scanning mobility particle sizer (SMPS). Issues related to the calibration of LII with SMPS are discussed, such as the effects of equivalence ratio and laser fluence. LII and SMPS have similar sensitivities to equivalence ratio in terms of total surface area and total volume, but the equivalence ratio needs to be carefully controlled as it highly affects the results. High laser fluence affects LII results by vaporizing soot particles, which reduces particle size. The effect of high laser fluence is particularly noticeable in the flame positions near the surrounding air such as at high flame heights and the outer combustion zone of nonpremixed flames where particle oxidation takes place. Overall, the comparison between LII and SMPS data yields encouraging results as they exhibit similar trends. The correspondence of LII and SMPS implies that SMPS could be applied as a valuable tool to calibrate LII signals and avoid the necessity of developing complex LII models.

Author: Henning Bockhorn
Publisher: Springer Science & Business Media
ISBN: 3642851673
Category : Science
Languages : en
Pages : 595

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Soot Formation in Combustion represents an up-to-date overview. The contributions trace back to the 1991 Heidelberg symposium entitled "Mechanism and Models of Soot Formation" and have all been reedited by Prof. Bockhorn in close contact with the original authors. The book gives an easy introduction to the field for newcomers, and provides detailed treatments for the specialists. The following list of contents illustrates the topics under review: