Uncertainty in Sampling and TEM Analysis of Soot Particles in Diesel Spray Flame

Kondo, Katsufumi; Aizawa, Tetsuya; Kook, Sanghoon; Pickett, Lyle M.

doi:10.4271/2013-01-0908

Cited by 41 publications

(50 citation statements)

References 7 publications

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“…Other relevant boundary conditions are given in Table 1. Transmission electron microscope (TEM) [25][26][27] studies of thermophoretically sampled soot from high-pressure flames show that primary particle sizes typically vary in between 5 and 40 nm. Figure 1 shows that in this range, the LII signal lifetime (time between 100 and 5 % of the peak signal) varies from ~6 to ~47 ns.…”

Section: General Approachmentioning

confidence: 99%

Sensitivity analysis for soot particle size imaging with laser-induced incandescence at high pressure

et al. 2015

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Section: General Approachmentioning

confidence: 99%

Sensitivity analysis for soot particle size imaging with laser-induced incandescence at high pressure

et al. 2015

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“…The identification and the measurement of the soot particles from the TEM images, however, can be complex as the soot TEM images are typically of low contrast, noisy and have non-uniform background signal level due to the nature of the TEM imaging process [38]. Additionally, the processing of the TEM images, which mainly proceeds through direct manual assessment, can be challenging and time-consuming as the soot samples have some degree of overlapping, in addition to having large variability in shape and size, even when they are collected from the same combustion environment [35,39]. A large number of TEM images would therefore need to be processed manually for statistically meaningful quantities to be generated.…”

Section: Motivationmentioning

confidence: 99%

“…The thermophoretic sampling method is a direct sampling approach that is widely-used by various research communities to provide quantitative particle/aggregate size and morphology information [30,39,67,68]. The thermophoretic sampling method, as its name implies, relies on the thermophoresis effect to drive the deposition of particulates from a high temperature environment, such as a flame, onto a cold substrate that is inserted into the medium [30,57].…”

Section: Microscope Imaging Techniquesmentioning

confidence: 99%

“…The transmission of the electrons through the image would also differ, depending on the local thickness differences in the film that is used to support the sampled particulates, which would then lead to the issue of nonuniform background signal level across the image [38]. All these issues imply that the detailed examination of the TEM images can be challenging to proceed other than through direct manual assessment by an operator, who has to visually distinguish the imaged objects from the background to extract the required morphological information [39]. For the cases where the imaged objects display significant variability in shapes and sizes, or experience some degree of overlapping, a large number of TEM images would need to be processed by the operator to generate statistically meaningful quantities to describe the characteristics of the imaged objects.…”

Section: Challenges Associated With Soot Tem Image Processingmentioning

confidence: 99%

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External irradiation effect on the growth and evolution of in-flame soot species

Wang

Chan

Kook

et al. 2016

Carbon

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350 words maximum: (PLEASE TYPE)External irradiation-soot species interaction is a subject that is of great interest due to ~s existing and future use in research and industrial sectors. An assessment of the impact of broadband radiation on the evolution of soot species within a laminar ethyleneair flame is therefore performed to Improve the fundamental understanding of the interaction process. Radiation at an average flux value of 120 kW/m'2 is provided by a solid-state plasma light to the lower region of the flame. Soot samples, thermophoretically collected at flame positions jhat are close and downstream from the irradiation location, are imaged using normal-resolution and high-resolution transmission electron microscopes (TEMs). The results, derived from processing the TEM images. reveal that the application of an external irradiation is found to increase the soot loading of the flame, and have a pronounced impact on the soot morphology, and influence the in-flame soot growth processes/mechanisms. The effects are also found to persist downstream from the irradiation location. The effects are mainly attributed to coupling of the broadband irradiation with the soot precursors, for the configuration used.Thermophoretic sampling, coupled with TEM imaging, is used to derive the required soot morphological data. The particulates characterization, however. can be complex when the images are of low contrast, noisy and have non-uniform background, or the samples collected have large variability in shape and size and have some degree of overlapping. A processing method that permits time-efficient automated characterization of particulates from the TEM grids, is therefore developed. The parameters required to be set to facilitate the automated process are identified and assessed. The proposed method is first applied to TEM images of samples acquired from the non-i rradiated flame. The automated resu~ is then compared with that derived via manual assessment, for validation purpose. The same analysis is also applied to samples extracted from the irradiated flame. which were previously observed to have different geometrical characteristics, to assess the morphological dependence of the proposed method. Using the optimized setting, the largest discrepancies associated with the automated results of primary particle diameter, fractal dimension and prefactor value of the aggregates for the tested cases, are approximately 3, 1 and 10%. respectively, when compared with lhe manual assessments.Declaration relating to disposition of project thesis/dissertation

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“…TEM observation images were digitally recorded with a CCD camera with resolution of 1024×1024. Observation locations were uniform distributed on the TEM grid to suppress statistic fluctuation [3]. TEM images were post processed using commercial software Image-Pro-Plus.…”

Section: Experimental Methodsmentioning

confidence: 99%

Soot Morphology and Size Distribution in Diesel Spray Flame via TEM Observation

Yan¹,

Cheng²,

Liu³

2017

Proceedings of the 2016 4th International Conference on Renewable Energy and Environmental Technology (ICREET 2016)

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Abstract. For better understanding of soot formation and oxidation processes in diesel spray flame, multi-point synchronous thermophoretic soot sampling was taken to obtain more information about soot morphology and size distribution in diesel spray flame. Soot samples were collected by thermophoretic sampling method in a constant volume combustion chamber. 9 different fixed sampling points were adopted for soot sampling and transmission electron microscope observation. Soot morphology and size distribution regularity in cone-shaped diesel spray flame were concluded with combustion status diagnoses. Detailed soot distribution and evolution regularity in both spray centerline horizontal direction and radial direction were gained by experimental results. Soot correlation reaction ratio in different region and combustion stage, reaction affecting factors were deeply discussed. IntroductionDiesel engine is always accompanied with soot emission issues. In order to reduce emission of diesel particulate matter, detailed understanding of soot formation in diesel combustion is necessary. Traditional soot particle measurement measure soot number, mass and size concentration in combustion aerosols. For measurement convenience, soot particle was usually treated as regular spheres and illustrated by its aerodynamical diameter in measurement. Actual soot particle structure is more complicated and able to reveal further information about soot evolution procedures. New particle sampling methods are extended for detail soot morphological investigations. Transmission electron microscope (TEM) is an advanced technique for soot morphology observation [1,2]. Most research focused on soot evolution procedures and conducted experiment mainly in flame transmission direction. In-flame soot sampling in radial direction was rarely inferred. With different equivalent ratio, temperature and combustion stage, soot morphology, size, distribution and evolution procedure are different in different flame region. Investigation about soot morphology and size distribution through whole spray flame, especially radial direction, is not sufficient. Those information can provide a new aspect to study soot formation processes.The present study aims to investigate the spray flame soot detail distribution with in-flame multi-point synchronous thermophoretic sampling and TEM observation. Combustion diagnosis were taken to find connection between soot evolution procedures and combustion process.

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Uncertainty in Sampling and TEM Analysis of Soot Particles in Diesel Spray Flame

Cited by 41 publications

References 7 publications

Sensitivity analysis for soot particle size imaging with laser-induced incandescence at high pressure

Sensitivity analysis for soot particle size imaging with laser-induced incandescence at high pressure

External irradiation effect on the growth and evolution of in-flame soot species

Soot Morphology and Size Distribution in Diesel Spray Flame via TEM Observation

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