Soot particles mechanism

The direct destruction of 03 by its reaction on soot particles generated by aircraft at midlatitudes has also been proposed, but given the large uncertainties in the mechanism and kinetics of this reaction, it is not clear that this will prove to be significant (Bekki, 1997 Lary et al., 1997). 

The introduction of more porous wall structures necessitates a closer look at the soot particle fate inside the wall and the deep-bed filtration mode starts to be important. Flow in porous media represents a challenging area of fluid mechanics and initial approaches (Bissett, 1984 Konstandopoulos et al., 2001,... 

At later times after the laser pulse heat conduction becomes the dominating heat loss mechanism (Will et al., 1995), and therefore, particles with different specific surface areas cool down differently, which is shown schematically in Figure 2 (Roth and Filippov, 1996 Will et al., 1995,1998). The local gas temperature adjacent to particles turns out to be the most critical parameter for the accuracy of size determination (Will et al., 1998), which however can be derived from the temperatures of the soot particles themselves (Schraml et al., 2000). 

Interactions Give the relative order of strength of interactions (weak, medium, strong) in the following series of pairs in low-polar solvent, dielectric constant e<10 (a) solvent + additive, (b) Calcium benzenesulfonates reverse micelles formation, (c) strong acid (HS) + N-base, (d) weak acid (HA) + N-base, (e) soot particle + reverse micelle, and (f) mechanically activated surface processes and molecular decomposition. 

The mechanism of action of surfactant additives. The operation of internal combustion (IC) engines results in the formation of by-products gases, soot particles, acids, water and free radical sources. 

Fig. 2.1. Steric stabilization mechanism of soot particles by formation of reverse micelles and solubilization...

Solubilization of insoluble oxidation products and soot particles. Reverse micelles (RMs) formations manage the prevention of agglomeration and the contamination process of insoluble oxidation particles and soot particles by both steric stabilization (Fig.2.1) and electrostatic stabilization mechanisms (Fig.2.2). The steric stabilization mechanism provides a physical barrier to agglomeration of particles by adsorption on particle surfaces. Adsorbed dispersant acts as a physical barrier to attraction between particles. 

Oxidation of SO2 in droplets, which contain various products, detectable in the atmosphere, is the measurement accepted as being real as it approaches atmospheric conditions. Studies upon the oxidation of SO2 in droplets, which contain soot particles, definitely show the effect of carbonaceous material in performing the conversion to SO"4. This process seems to be of relevant importance in polluted areas. As far as liquid phase oxidation of SO2 is concerned, it seems that the uncatalyzed oxidation of SO2 by ozone or hydrogen peroxide is probably the dominant mechanism in the droplet phase. 

The foregoing observations lead us to support a mechanism of ionic nucleation whereby large hydrocarbon ions are formed which can then agglomerate large neutral hydrocarbons to form soot particles by surface growth. The chemical nature of the large hydrocarbon ions and the mechanism of their formation are discussed below. 

Although it is not yet possible to assess the effect of photoionization in flames, this mechanism may well have an important contribution to ion formation, especially toward the end of the process when polyaromatic hydrocarbons are adsorbed on the surface of soot particles. 

Inherent in the developments given is the assumption that all adsorption sites will yield a product oxide. In considering the heterogeneous oxidation of coal char or soot particles, however, it is most apparent not all sites are reactive, nor do they all have the same reactivity. In an effort to obtain a more detailed analysis of the burning rates of such materials as a function of temperature, Radcliffe and Appleton [31] proposed a mechanism that leads to the development of the semiempirical correlation of Nagle and Strickland-Constable [32]. Indeed, on the basis of structural similarities, these investigators have suggested that the rate of oxidation of soot and char-like materials should be equivalent. In their mechanism of surface oxidation, they posited two types of reaction sites in the exposed area... 

Regarding the mechanism [9], there is evidence for the formation of iron oxides encapsulated by the soot particles. These particles seem to maintain a catalytic cycle. X-ray diffractometry showed that ferrocene decomposes in the colder flame zones to iron oxide. 

Frenklach, M. Wang, H. Detailed mechanism and modeling of soot particle formation. In Soot Formation in Combustion Bockhorn, H., Ed. Springer Berlin, 1994 165. 

Several kinetic mechanisms have been proposed in the literature for modelling the formation and growth of soot particles (Appel et al., 2000 Balthasar and Frenklach, 2005 D Anna et al., 2001a Frenklach and Wang, 1994 Richter et al., 2005). All these mechanisms agree that the process can be described in terms of the following major steps ... 

It is possible that the wetting of the soot particle by the molten salt imposes a limitation on the transport of oxygen to the soot particle, as suggested by McKee [3]. On the other hand, an oxidation cycle with the catalyst as an intermediate, can be the dominating mechanism. This would imply that the complete coverage of the soot vwth a film of the liquid salt is perhaps favourable. 

Quantitative Chemical Mechanism for Heterogeneous Growth of Soot Particles in Premixed Flames... 

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