A radical approach to soot formation

Thomson, Murray J.; Mitra, Tirthankar

doi:10.1126/science.aau5941

Cited by 102 publications

(39 citation statements)

References 6 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Note that the chain propagation reactions involving RSRs has been confirmed by quantum computations [138]. However, detailed rates for the various proposed radical chain propagation reactions still need to be determined so that a complete mechanism can be assembled to test the capabilities of the CHRCR mechanism in predicting the formation of large molecular species and soot [273].…”

Section: C2h2 → 2csoot + H2 R45 C6h6 → 6csoot + 3h2 R46mentioning

confidence: 97%

“…While previous mechanisms for covalent cluster formation required repeated high energy barrier activation of stable PAHs (and thus not perfectly compatible with the rapid nucleation of soot, even in low temperature radical-starved regions), the recently proposed clustering of hydrocarbon by radical chain reaction (CHRCR) mechanism [138] highlights the role of radical chain propagation through resonantly stabilized radicals. This new CHRCR mechanism overcomes the issue of low molecular growth rates associated with existing chemical nucleation mechanisms and also allows σ-dimerization from large RSRs [138,273]. Although promising, one challenge is that detailed reaction rates must be established for the proposed reactions so that an extensive kinetic mechanism can be assembled to test whether CHRCR can explain experimental features on soot formation.…”

Section: Summary Challenges and Prospectsmentioning

confidence: 99%

See 1 more Smart Citation

Soot formation in laminar counterflow flames

Wang

Chung

2019

Progress in Energy and Combustion Science

360

116

View full text Add to dashboard Cite

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.

show abstract

Section: C2h2 → 2csoot + H2 R45 C6h6 → 6csoot + 3h2 R46mentioning

confidence: 97%

Section: Summary Challenges and Prospectsmentioning

confidence: 99%

Soot formation in laminar counterflow flames

Wang

Chung

2019

Progress in Energy and Combustion Science

360

116

View full text Add to dashboard Cite

show abstract

“…In addition, it could be seen from the results of SEM images that the char layer surface of formulation 2 in addition of PHC was greatly different from formulation 1. EPDM insulation materials (Organic polymers containing hydrocarbons) produced PAH 33 in the process of ablation, and PAH was an organic phase with benzene ring structure. Also, PHC contained organic phase and was weak in polarity.…”

Section: Resultsmentioning

confidence: 99%

Effect of hybrid cross‐linked polyphosphazene microspheres on ablative and mechanical properties of ethylene propylene diene monomer

Chen

He²,

Liu

et al. 2021

J of Applied Polymer Sci

View full text Add to dashboard Cite

Polymeric ablative materials (PAMs) are widely used in spacecraft currently for thermal insulation. However, it is challenging to find a single filler that can improve both ablative and mechanical properties of PAMs. In this study, a new type of hybrid cross‐linked polyphosphazene microspheres (PHC) is added to ethylene propylene diene monomer (EPDM) composites as a filler for the first time and its influence on the ablation, mechanical, and thermal properties of EPDM is investigated. The results show that the addition of 3 phr PHC increases the ablation performance by about 10% and enhances the mechanical properties by 20% approximately. In addition, the ablation mechanism is studied in accordance with SEM, FTIR, and Raman spectroscopy. On the one hand, PHC has the effect of catalyzing carbonization, thus increasing the rate of residual carbon; on the other hand, PHC changes the morphology of the char layer, forming a cross‐linked structure containing P─O─Si bonds on the surface. The findings regarding catalyzing carbonization and the special char layer structure could guide the design of ablative materials.

show abstract

“…The PHRR of AL5 and AL10 is nearly the same, whereas the PRSR of AL10 is 10.7% lower than that of AL5. The reduction of PRSR may result from the transition metal ions in the LDHs (Zn 2+ ), which can catalyze the thermal degradation of the polymer [34], suppress the growth of polyaromatic hydrocarbons and the growth of their clusters, and reduce the formation of soot [35].…”

Section: Resultsmentioning

confidence: 99%

Flame-Retardant Mechanism of Layered Double Hydroxides in Asphalt Binder

et al. 2019

View full text Add to dashboard Cite

The flame retardancy of asphalt binders with layered double hydroxides (LDHs) was investigated using limiting oxygen index (LOI) and cone calorimeter tests. The flame-retardant mechanism of the LDHs was also studied with thermogravimetry and differential scanning calorimetry (TG–DSC), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The cone calorimeter testing results indicated that 2 wt.% of the LDHs can decease the peak heat and smoke release rate of asphalt binders. Because a low dose of LDHs can be well dispersed in asphalt binder and favor the formation of polyaromatic structures during combustion, the thermal oxidation resistance and compactness of the char layer can be improved. The LOI of asphalt binder can be increased and the heat and smoke release during combustion can be decreased with 25 wt.% LDHs. The decomposition of LDHs can absorb the heat release of the initial two stages of asphalt combustion and reduce the burning rate of asphalt. Due to the loss of loosely bound water in the LDHs during the blending process and the decrease of dispersibility at a high LDH dose, the improvement of thermal stability is limited.

show abstract

A radical approach to soot formation

Abstract: Chain reactions of resonance-stabilized radicals turn molecules into clusters and nanoparticles

Cited by 102 publications

References 6 publications

Soot formation in laminar counterflow flames

Soot formation in laminar counterflow flames

Effect of hybrid cross‐linked polyphosphazene microspheres on ablative and mechanical properties of ethylene propylene diene monomer

Flame-Retardant Mechanism of Layered Double Hydroxides in Asphalt Binder

Contact Info

Product

Resources

About