Particle synthesis in flames

Roth, P.

doi:10.1016/j.proci.2006.08.118

Cited by 168 publications

(104 citation statements)

References 106 publications

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“…Our formalism for grain growth does not consider deposition of atoms and molecules on the surface of small grains. Once the radius of grains reaches several tens of Å, the growth of the particles proceeds through surface deposition, which is a fast process, and coagulation and coalescence, as observed in flames (Roth 2007). For deposition, the sticking coefficient S of an atom or molecule on the surface of grains depends on the chemical composition of the accreting species and the grain surface, and the surface and gas temperature.…”

Section: Condensation Of Dust Grainsmentioning

confidence: 99%

Dust formation in the oxygen-rich AGB star IK Tauri

Gobrecht

Cherchneff

Sarangi

et al. 2015

A&A

185

289

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Aims. We model the synthesis of molecules and dust in the inner wind of the oxygen-rich Mira-type star IK Tau by considering the effects of periodic shocks induced by the stellar pulsation on the gas and by following the non-equilibrium chemistry in the shocked gas layers between 1 R and 10 R . We consider a very complete set of molecules and dust clusters, and combine the nucleation phase of dust formation with the condensation of these clusters into dust grains. We also test the impact of increasing the local gas density. Our derived molecular abundances and dust properties are compared to the most recent observational data. Methods. A semi-analytical formalism based on parameterised fluid equations is used to describe the gas density, velocity, and temperature in the inner wind. The chemistry is described by using a chemical kinetic network of reactions and the condensation mechanism is described by a Brownian formalism. A set of stiff, ordinary, coupled differential equations is solved, and molecular abundances, dust cluster abundances, grain size distributions and dust masses are derived. Results. The shocks drive an active non-equilibrium chemistry in the dust formation zone of IK Tau where the collision destruction of CO in the post-shock gas triggers the formation of C-bearing species such as HCN and CS. Most of the modelled molecular abundances agree well with the latest values derived from Herschel data, except for SO 2 and NH 3 , whose formation may not occur in the inner wind. Clusters of alumina, Al 2 O 3 , are produced within 2 R and lead to a population of alumina grains close to the stellar surface. Clusters of silicates (Mg 2 SiO 4 ) form at larger radii (r > 3 R ), where their nucleation is triggered by the formation of HSiO and H 2 SiO. They efficiently condense and reach their final grain size distribution between ∼6 R and 8 R with a major population of medium size grains peaking at ∼200 Å. This two dust-shell configuration agrees with recent interferometric observations. The derived dust-to-gas mass ratio for IK Tau is in the range 1-6 × 10 −3 and agrees with values derived from observations of O-rich Mira-type stars. Conclusions. Our results confirm the importance of periodic shocks in chemically shaping the inner wind of AGB stars and providing gas conditions conducive to the efficient synthesis of molecules and dust by non-equilibrium processes. They indicate that the wind acceleration will possibly develop in the radius range 4-8 R in IK Tau.

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Section: Condensation Of Dust Grainsmentioning

confidence: 99%

Dust formation in the oxygen-rich AGB star IK Tauri

Gobrecht

Cherchneff

Sarangi

et al. 2015

A&A

185

289

View full text Add to dashboard Cite

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“…1 reports the main characteristics of the Diesel fuel used for the experimental analysis: as it can be seen, it is a fuel very close to the commercial ones used for automotive applications. A rather similar apparatus was used to characterise liquid fuels spray flames [5] and for controlled nano-particles synthesis by flame spray pyrolysis [6][7][8][9][10]. The Al 2 O 3 nanoparticles used are produced by Nanostructured and Amorphous Materials Inc. (nominal average diameter=10 n m) with 99% cert ified purity.…”

Section: Experimental Set-upmentioning

confidence: 99%

Experimental Analysis of the Influence of Inert Nano-additives upon Combustion of Diesel Sprays

Solero¹

2012

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Recent experimental studies report that addition of nanoparticles (tipically metal o xides nanopowders, such as Al 2 O 3 ) can somehow mod ify the ignition mechanism of liquid fuels, probably influencing and accelerating the thermal exchange process between the fuel droplets and the surrounding air. In this paper it has been experimentally analised a stationary Diesel spray, produced by a gas assisted atomizer, preliminarily comparing the behaviour of the flame generated using the unseeded fuel with that one of the same fuel addit ivated with Al 2 O 3 nanoparticles. Results obtained through light emission analysis are encouraging, in the sense that the presence of a small nano-additive quantity (0.1% in volu me) seems to produce effects similar to a shift towards higher flame ventilation, with a possible positive consequence upon combustion stability and efficiency.

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“…In our experiments with the perforated ceramic tile burner we have Nanoparticles can be produced naturally nearly in every flame. Today this phenomenon is used for gas phase combustion synthesis of a variety of inorganic oxides in the form of fine particles amounting to millions of tons annually [1]. They are used industrially as pigments, opacities, catalysts etc.…”

Section: Introductionmentioning

confidence: 99%

Size distribution of silica nanoparticles: its impact on green energy

Dutka¹,

Turkin

Vainchtein³

et al. 2016

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1The kinetics of formation of silica fractal-like aggregates during combustion of a stoichiometric methane/air mixture with the hexamethyldisiloxane admixture is studied. Oxidation of hexamethyldisiloxane proceeds very fast with formation of SiO 2 molecules and compact silica clusters at a height of a few millimeters above the burner. At a sufficiently high concentration of hexamethyldisiloxane random collisions of nanoparticles leads to agglomerates with fractal-like structure. The transmission electron microscopy is combined with the theoretical analysis to find conditions for formation of silica fractal-like aggregates. The onset of fractal aggregate formation is discussed by studying the characteristic time scales of collisions and coalescence. One dimensional model is formulated to describe the evolution of the size distribution of fractal-like silica particles undergoing generation, convection, sintering and Smoluchowski coagulation. The simulation results are compared to experimental data.

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Particle synthesis in flames

Cited by 168 publications

References 106 publications

Dust formation in the oxygen-rich AGB star IK Tauri

Dust formation in the oxygen-rich AGB star IK Tauri

Experimental Analysis of the Influence of Inert Nano-additives upon Combustion of Diesel Sprays

Size distribution of silica nanoparticles: its impact on green energy

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