Sooting flame

Gerecke, A., A. Thielmann, L. Gutzwiller, and M. J. Rossi, The Chemical Kinetics of HONO Formation Resulting from Heterogeneous Interaction of N02 with Flame Soot, Geophys. Res. Lett., 25, 2453-2456 (1998). 

Near rich limits of hydrocarbon flames, soot is sometimes produced in the flame. The carbonaceous particles—or any other solid particles— easily can be the most powerful radiators of energy from the flame. The function k(t) is difficult to compute for soot radiation for use in equation (21) because it depends on the histories of number densities and of size distributions of the particles produced for example, an approximate formula for Ip for spherical particles of radius with number density surface emissivity 6, and surface temperature is Ip = Tl nrle ns) [50]. These parameters depend on the chemical kinetics of soot production—a complicated subject. Currently it is uncertain whether any of the tabulated flammability limits are due mainly to radiant loss (since convective and diffusive phenomena will be seen below to represent more attractive alternatives), but if any of them are, then the rich limits of sooting hydrocarbon flames almost certainly can be attributed to radiant loss from soot. 

Soot samples collected from the engine running on fuel with additive were studied. Printex-U, a flame soot supplied by Degussa. was used as a reference material. 

Chang H, Charalampopoulos TT (1990) Determination of the wavelength dependence of refractive indices of flame soot. Phil Trans Roy Soc Lond A 430(1880) 577-591... 

Ice particle measurements in the expansion experiment with 40% OC soot aerosol markedly differ from the 16% OC sample. Note that the optical particle spectrometer hardly detects any ice particles. Additionally, extinction signatures of ice are barely visible in the infrared spectra and diere is only a weak intensity increase of the back-scattered laser light in course of the expansion. The number concentration of ice crystals is less than 10 cm, thus < 1% of the seed aerosol particles act as deposition ice nuclei. In contrast to the 16% OC experiment, no precise critical ice saturation ratio can be specified for the 40% OC soot sample. RHi continues to increase to 190% because very little water vapour is lost on the small surface area of the scarce ice crystals. In summary, die comparison of the two expansion experiments provides first evidence that a higher fraction of organic carbon notably suppresses the ice nucleation potential of flame soot particles. 

Figure 6- Measured time profiles of pressure, gas temperature, relative humidity with respect to ice, back-scattered laser light intensity, as well as ice particle number concentration for two expansion cooling experiments with different flame soot aerosol samples from the CAST burner as seed aerosol (Mdhler et al, 2004b). See text for details.

Mohler, O., C. Linke, H. Saathoff, M. Schnaiter, R. Wagner and U. Sehurath Ice nueleation on flame soot aerosol of different organic carbon content, Meteorol Z. (2004b) accepted for publication. 

Since it is difiScuh to obtain diesd soot with constant prop es (the composition dq> ids on the engine load) a model soot was applied (Printex-U, a flame soot kindly provided by Degussa). This soot has a N2-BET surface area of 96 mV and contains approximately 5 wt% of adsorbed hydrocarbons and 0 2-0.4 wt% sulfur. Catalytic soot oxidation temperatures were d ermined in a thermobalance (STA 1500H). About 4 mg catalyst, 2 mg soot and 54 mg SiC were applied as a sample. A heating rate of 10 K/min and a flow rate of 50 ml/min 21 vol% O2 in N2 wa"e used. The maximum of the DSC curve was defined as the oxidation temperature. Samples refored to as tight contact were intensively milled in a ball mill for one hour, before dilution with SiC and thermal analysis, whereas loose contact was established by simply mixing of the catalyst and soot with a spatula. 

J. C. Ku and K-H Shim, The Effects of Refractive Indices, Size Distribution, and Agglomeration on the Diagnostics and Radiative Properties of Flame Soot Particles, in W. L. Grosshandler and H. G. Semerjian (eds.), Heat and Mass Transfer in Fires and Combustion Systems, ASME HTD-vol. 148, ASME, New York, 1990. 

Combustion processes can create pollutant emissions other than carbon monoxide and oxides of nifrogen. Unbumed hydrocarbons (UHC) is a term describing any fuel or partially oxidized hydrocarbon species that exit the stack of a furnace. The cause for these emissions is typically due to incomplete combustion of the fuel from poor mixing or low furnace temperature. A low temperature environment can be created by operating the furnace at a reduced firing rate or turndown. Particulate matter (commonly called soot) is often produced from fuel rich regions in diffusion flames. Soot becomes smoke if the rate of formation of soot exceeds the rate of oxidation of soot. Oxides of sulfur are formed when sulfur is present in the fuel. 

As die composition of diesel particulates (e.g. fi action of adsorbed hydrocarbons) depends upon many motor characteristics as engine load, speed, and various temperatures, it is difficult to collect batches of soot with constant properties. Tlierefore, we choose to work with printex-U (a flame soot supplied by Degussa AG) as a model soot. Properties of tliis model soot and diesel particulates collected from a one cylinder direct injected diesel engine (Yanmar L90E diesel generator set) are listed in Table 1. 

This information on in-flame soot radiation and triatomic gas radiation has been known for some time, but recent developments may be changing the picture ... 

Flame soot Paracetamol powder Cocoa Aluminium dust... 

The result from the solid plume radiation model is smaller than the point source model. This is most likely due to consideration of the radiation obscuration by the flame soot, a feature not treated direedy by the point source model. The differences between the two models might be greater at closer distance to the pool fire. 

Rogaski et al. (1997) and Koehler et al. (1999) reported the initial uptake coefficients of y<(3 l) x 10 (298 K), and (2 l)x 10 (173 K), respectively, for geometric surface area using the combustion flame soot. The value decreases to one thirty-third when the roughness of the surface is considered (Koehler et al. 1999). However, since the uptake coefficient decreases with... 

Karagulian, F., Santschi, C., Rossi, M.J. The heterogeneous chemical kinetics of N2O5 on CaCOa and other atmospheric mineral dust surrogates. Atmos. Chem. Phys. 6, 1373-1388 (2006) Karagulian, F., Rossi, M.J. Heterogeneous chemistry of the NO3 free radical and N2O5 on decane flame soot at ambient temperature reaction products and kinetics. J. Phys. Chem. A 111, 1914-1926 (2007)... 

Lelievre, S., Bedjanian, Y., Laverdet, G., Le Bras, G. Heterogeneous reaction of NO2 with hydrocarbon flame soot. J. Phys. Chem. A 108, 10807—10817 (2004)... 

Sakaguchi, S., Morita, A. Mass accommodation mechanism of water through mmiolayer fihns at water/vapor interface. J. Chem. Phys. 137(064701), 9 (2012). doi 10.1063/1.4740240 Salgado-Munoz, M.S., Rossi, M.J. Heterogeneous reactions of HNO3 with flame soot generated under different combustion conditions. Reaction mechanism and kinetics. Phys. Chem. Chem. 

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