Can soot primary particle size distributions be determined using laser-induced incandescence?

Bauer, Florian; Daun, Kyle J.; Huber, Franz; Will, Stefan

doi:10.1007/s00340-019-7219-7

Cited by 35 publications

(17 citation statements)

References 62 publications

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“…The particular reaction conditions in terms of molecular fuel structure, temperature, pressure, and other variables affect the internal nanostructure, chemical composition, mobility, and reactivity of soot particles [244] , [245] , [246] , [247] , [248] , [249] , which may be different in technical devices from laboratory reactors and flames. Attempts to link between PAHs, high-molecular-weight carbon structures, and initial particles has motivated theoretical work [199 , 250] as well as experimental approaches including in-situ LII [251] , [252] , [253] , probe-sampling tandem mass spectrometry (MS-MS) [254] , and ex-situ microscopy [207 , 252 , [255] , [256] , [257] , [258] to image carbon structures and particles while considering also probe sampling effects [259] .…”

Section: Selected Combustion Chemistry Advances – Overview and Recentmentioning

confidence: 99%

Combustion in the future: The importance of chemistry

Kohse‐Höinghaus

2021

Proceedings of the Combustion Institute

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Combustion involves chemical reactions that are often highly exothermic. Combustion systems utilize the energy of chemical compounds released during this reactive process for transportation, to generate electric power, or to provide heat for various applications. Chemistry and combustion are interlinked in several ways. The outcome of a combustion process in terms of its energy and material balance, regarding the delivery of useful work as well as the generation of harmful emissions, depends sensitively on the molecular nature of the respective fuel. The design of efficient, low-emission combustion processes in compliance with air quality and climate goals suggests a closer inspection of the molecular properties and reactions of conventional, bio-derived, and synthetic fuels. Information about flammability, reaction intensity, and potentially hazardous combustion by-products is important also for safety considerations. Moreover, some of the compounds that serve as fuels can assume important roles in chemical energy storage and conversion. Combustion processes can furthermore be used to synthesize materials with attractive properties. A systematic understanding of the combustion behavior thus demands chemical knowledge. Desirable information includes properties of the thermodynamic states before and after the combustion reactions and relevant details about the dynamic processes that occur during the reactive transformations from the fuel and oxidizer to the products under the given boundary conditions. Combustion systems can be described, tailored, and improved by taking chemical knowledge into account. Combining theory, experiment, model development, simulation, and a systematic analysis of uncertainties enables qualitative or even quantitative predictions for many combustion situations of practical relevance. This article can highlight only a few of the numerous investigations on chemical processes for combustion and combustion-related science and applications, with a main focus on gas-phase reaction systems. It attempts to provide a snapshot of recent progress and a guide to exciting opportunities that drive such research beyond fossil combustion.

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Section: Selected Combustion Chemistry Advances – Overview and Recentmentioning

confidence: 99%

Combustion in the future: The importance of chemistry

Kohse‐Höinghaus

2021

Proceedings of the Combustion Institute

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“…Liu et al [39,41] studied the relation between n p and the signal decay, providing a method to account for the shielding effect. 3 Accounting for n p may have a strong impact on the results [58,59]. As an example, the reevaluation of the measured TiRe-LII signal with n p = 100 instead of n p = 1 by Bladh et al [10] led to the drop of the derived mean d pp by 30%.…”

Section: Number Of Primary Particles In the Aggregatementioning

confidence: 99%

A forward approach for the validation of soot sizing models using laser-induced incandescence (LII)

et al. 2020

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While validating the numerical modeling of the primary particle size distribution (PPSD) in sooting flames, a common practice is to compare the numerical results to the corresponding experimental data obtained with the Time-Resolved Laser-Induced Incandescence (TiRe-LII) technique. Since the PPSD is not directly measured by TiRe-LII, but derived with a postprocessing procedure, various uncertainties and errors can potentially affect the consistency of such comparison requiring the estimation of many input parameters. On the contrary, nowadays, detailed numerical simulations provide access to a more complete set of data, which can be used to reconstruct the incandescence signal. In this work, a forward approach for the generic validation of numerical models for the PPSD is performed. It is based on the numerical reconstruction of the temporal evolution of the incandescence from the numerical results and its comparison with the measured signal. First, two indexes are proposed to quantify the agreement between the numerically synthesized and the measured signals. Then, the effectiveness of the proposed approach is demonstrated a priori by quantifying the potential errors that can be avoided with this new strategy compared to the classical approach. Finally, the feasibility of the proposed procedure is proven by comparing synthesized signals to the experimental ones available in the literature for a laminar premixed flame. It is shown that the proposed approach can be used for strengthening the analysis on numerical model performances in addition to the classical approach.

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“…While the accuracy is somewhat reduced (due to optical and heat transfer parameters remaining in the simulation of the signal curve) [24], the single-color approach is well suited to describe how soot size evolves within a flame. The heat transfer model used to determine the primary particle size is described in detail in previous work [7]. The measurement model presented therein is based on polydisperse size distributions for the primary particles diameter d p as well as the radius of gyration of the aggregates R g .…”

Section: Modelmentioning

confidence: 99%

“…The terms Q abs ,Q cond andQ subl are the rates of energy transfer through absorption, heat conduction and sublimation, respectively, possible additional mechanisms that only have a small share in balance such as phototoemission are neglected. One feature of the model described in [7] is the coupling with a Bayesian approach. It allows to treat certain parameters of the model, e.g., the bath gas temperature, as stochastic variables rather than deterministic values.…”

Section: Modelmentioning

confidence: 99%

“…To model the cooling accurately, ambient conditions, such as the bath gas temperature and local fluence of the laser radiation have to be known precisely [5,6]. Even small uncertainties in those ambient parameters can lead to large deviations and uncertainties in the determined particle size, a result of the ill-posedness of the problem [7,8]. Therefore, accurate measurements of the absolute particle size distribution might be challenging, while the determination of relative changes in the particle sizes within certain regions in a semi-quantitative way are very beneficial, especially for large measurement volumes.…”

Section: Introductionmentioning

confidence: 99%

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Three-dimensional particle size determination in a laminar diffusion flame by tomographic laser-induced incandescence

Bauer

Cai

et al. 2020

Appl. Phys. B

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Non-intrusive measurement techniques are required to gain a comprehensive understanding about the processes of soot formation, growth and oxidation. Time-resolved laser-induced incandescence (TiRe-LII), commonly performed 0D or 2D within a flame, has proven to be a very suitable tool for the in situ sizing of soot primary particles. In this work, the technique is expanded to the third dimension by employing volumetric illumination and coupling it with a tomographic approach, which allows to computationally gain 3D information from 2D images taken at various angles. To minimize experimental cost, an approach using nine fiber bundles arranged in a semicircle around the flame and imaging the light onto a single camera is used. The technique is demonstrated on an ethene diffusion flame on a standard burner, providing spatially resolved 3D particle sizes. One focus of this work is to reveal the influence of input parameters such as the local bath gas temperature, which we measured by two-color pyrometry, and local laser fluence, which are both required for an accurate evaluation of the local particle size. It is shown that the assumption of an average temperature may result in a wrong picture even of qualitative soot size evaluation. In the end, a concept is proposed for a simultaneous determination of the 3D distribution of particle sizes through TiRe-LII and the required bath gas temperature via two-color pyrometry using a tomographic approach with only three cameras.

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Can soot primary particle size distributions be determined using laser-induced incandescence?

Cited by 35 publications

References 62 publications

Combustion in the future: The importance of chemistry

Combustion in the future: The importance of chemistry

A forward approach for the validation of soot sizing models using laser-induced incandescence (LII)

Three-dimensional particle size determination in a laminar diffusion flame by tomographic laser-induced incandescence

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