A numerical and experimental study of Polycyclic Aromatic Hydrocarbons in a laminar diffusion flame

Verhoeven, L.M.; Oliveira, M. H. de Andrade; Lantz, Andreas; Li, Bo; Li, Zhongshan; Luijten, Ccm Carlo; Oijen, J.A. van; Aldén, Marcus; Goey, de Lph Philip

doi:10.1016/j.proci.2012.06.016

Cited by 15 publications

(8 citation statements)

References 25 publications

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“…The signal intensity can also be used to qualitatively evaluate the concentrations of these different classes of PAHs. This method is particularly useful in evaluating fuel effects on PAH formation by comparing the relative concentrations of PAHs as represented by LIF signal intensity among flames with different fuels or fuel additives [441][442][443][444][445][446][447]. Nevertheless, it is important to note that PAH LIF signal can be highly dependent on temperature [448].…”

Section: Optically-based In-situ Methodsmentioning

confidence: 99%

Soot formation in laminar counterflow flames

Wang

Chung

2019

Progress in Energy and Combustion Science

360

116

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Many practical soot-emitting combustion systems such as diesel and jet engines rely on diffusion flames for efficient and reliable operation. Efforts to mitigate soot emissions from these systems are dependent on fundamental understanding of the physicochemical pathways leading from fuel to soot in laminar diffusion flames. Existing diffusion flame−based soot studies focused primarily on overventilated coflow flame where the fuel gas (or vapor) issues from a cylindrical tube into a co-flowing oxidizer, and counterflow flame, where a reacting zone is established between two opposing streams of fuel and oxidizer. As a canonical diffusion flame configuration, laminar counterflow diffusion flames have been widely used as a highly controllable environment for soot research, enabling significant progress in the understanding of soot formation for several decades. In view of the possibility of fuel/oxidizer premixing in practical systems, counterflow partially premixed flames have also been studied. In the present work we intend to provide a comprehensive review of the researches on various aspects of soot formation utilizing counterflow flames. Major processes of soot formation (formation of gas phase soot precursors, soot inception and surface reactions, as well as particle-particle interactions) are examined first, with focus on the most recent (post-2010) research progress. Experimental techniques and associated challenges for the measurement of soot-related properties (some knowledge of which is helpful for full appreciation of the experimental data to be reviewed) are then introduced. This is followed by a detailed description of soot evolution in counterflow flames, which is complemented by a discussion on the similarity and differences of the sooting structures between counterflow and coflow diffusion flames. Parametric studies of the effects of fuel molecular structure, fuel additive, partial-premixing, pressure, temperature, stoichiometric mixture fraction, and residence time on soot formation in counterflow flames will then be addressed in detail. This review concludes with a summary of the knowledge and challenges gathered and demonstrated through decades of research, and an outlook on opportunities for future counterflow flame−based soot research towards a more complete understanding of soot formation and the development of novel techniques for soot mitigation in practical combustion devices.

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Section: Optically-based In-situ Methodsmentioning

confidence: 99%

Soot formation in laminar counterflow flames

Wang

Chung

2019

Progress in Energy and Combustion Science

360

116

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“…which was fitted with a UV 100 mm f/2.8 Cerco lens and a combination of UG11 and WG305 Schott glass filters. of excitation wavelengths from UV to visible [13,42] with the corresponding emission wavelength dependent on the number of aromatic rings possessed by the PAH molecule, and increasing with the number of aromatic rings [11,21,43]. Vander Wal et al [44] reported that with excitation wavelength below 300 nm, PAH with 2 or 3 aromatic rings can fluoresce between 300-350 nm while PAHs of 4 rings or more can exhibit fluorescence in the range 300-700 nm.…”

Section: Simultaneous Oh and Pah Lif Imagingmentioning

confidence: 99%

“…Vander Wal et al [44] reported that with excitation wavelength below 300 nm, PAH with 2 or 3 aromatic rings can fluoresce between 300-350 nm while PAHs of 4 rings or more can exhibit fluorescence in the range 300-700 nm. More specifically, investigations in [11,43] assigned PAH fluorescence in the visible range of 400 -480 nm to larger PAHs of 3 to 5 rings.…”

Section: Simultaneous Oh and Pah Lif Imagingmentioning

confidence: 99%

Study of polycyclic aromatic hydrocarbons (PAHs) in hydrogen-enriched methane diffusion flames

Ezenwajiaku

Talibi

Doan

et al. 2019

International Journal of Hydrogen Energy

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Polycyclic aromatic hydrocarbons (PAHs) are the carcinogenic components of soot. Detailed understanding of PAH formation characteristics is required for development of effective strategies to curtail PAH formation and reduce soot in combustion devices. This study presents an experimental methodology to analyse PAH formation characteristics of a non-premixed methane-air flame with and without hydrogen (H2) addition, using simultaneous planar laser induced fluorescence (PLIF) imaging of PAH and hydroxyl radical (OH). OH PLIF was used to represent peak temperature regions in the flame front. One-dimensional, opposed-jet laminar non-premixed flame simulations were also carried out for the same fuel mixture conditions. This work describes comparison of trends from both sets of studies. PAH fluorescence intensity values were observed to increase with increasing height above burner, however this rate of increase reduced with H2 addition. This observed rate of change in PAH fluorescence (that is, PAH growth characteristics) is indicative of the sooting potential of the fuel mixture. PAH fluorescence from experiments and PAH concentration from simulation show strong reduction with increase in H2 addition. The percentage reduction in PAH fluorescence signal with H2 addition closer to the burner tip was of a similar magnitude to that observed with flame simulations. The reduction in PAH with H2 addition could be attributed to the reduction in acetylene and propargyl concentrations, and reduced H-abstraction rates, which reduced the availability of active sites for PAH growth. The proposed experimental methodology for PAH measurements can be readily applied to any fuel mixtures.

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“…Unfortunately, it is difficult to obtain information about diesel in-cylinder PAHs because of the associated high pressure and high temperature environment. The usual approach is to develop predictive numerical models employing detailed PAH mechanisms obtained from canonical systems such as laminar, counterflow diffusion and turbulent diffusion flames [1,[9][10][11][12]. When applied to diesel engine simulations, these PAH mechanisms are simplified before being incorporated as a part of http://dx.doi.org/10.1016/j.fuel.2015.05.053 0016-2361/Ó 2015 Elsevier Ltd. All rights reserved.…”

Section: Introductionmentioning

confidence: 99%