Gasless combustion

I.P. Borovinskaya, A New Class of Combustion Processes , Combustion Science Technology 10 (1975), 195—201. See also A.G. Merxhanov, Regularities and Mechanism of Combustion of Pyrotechnic Titanium Boron Mixtures , 4th Symposium, see Ref 148, See also V. Maslov et al, On Gasless Combustion Mechanism , FizikaGoreniaiVziyva 12, No 5... 

There are various types of pyrolants that generate gasless combustion products. The pyrolant composed of aluminum powder and iron oxide powder generates aluminum oxide and metallic iron as combushon products. This reaction represented by... 

The chosen combinations of these chemicals and metals depend on the requirements of the specific application. Gasless combustion prevents pressure increase in a closed combustion chamber. Some combinations of metal particles and metal oxide particles or of metal particles and crystalline oxidizers are chosen as chemical ingredients of gasless pyrolants. On the other hand, hydrocarbon polymers are used to obtain combustion products of low molecular mass, such as H2O, CO, CO2, and H2. High pressure is thus obtained by the combustion of hydrocarbon polymers. Table 10.6 shows the chemical ingredients used to formulate various types of pyrolants. 

As an especially simple example of an intrinsic instability, let us first consider the planar, adiabatic, gasless combustion of a solid, mentioned at the beginning of Section 7.1 and discussed in the middle of Section 7.4. The statement of energy conservation in the solid may be taken to be equation (56) with a heat-release term, say w, added to the right-hand side. Although Wq properly depends on the reactant concentration, a temperature-explicit... 

To apply the results to the gasless combustion problem introduced at the beginning of this section, we let B — 1 and find that intrinsic instability... 

The mechanism of the instability that has been described here suggests that intrinsic instability of gasless combustion evolves to an inherently pulsating mode of propagation rather than to a sustained explosion or... 

From the viewpoint of chemical nature, three main types of CS processes can be distinguished. The first, gasless combustion synthesis from elements, is described by the equation... 

Based on their analyses, and incorporation of additional details, we have outlined some general relationships for gasless combustion synthesis of materials from elements (type 1), as shown schematically in Fig. 3. Both characteristic features of the process, the combustion wave propagation velocity and maximum temperature, have maximum values when the composition of the green mixture corresponds to the most exothermic reaction for a given system (Fig. 3a). In gen-... 

The microstructural models described here represent theoretical milestones in gasless combustion. Using similar approaches, other models have also been developed. For example, Makino and Law (1994) used the solid-liquid model (Fig. 20c) to determine the combustion velocity as a function of stoichiometry, degree of dilution, and initial particle size. Calculations for a variety of systems compared favorably with experimental data. In addition, an analytical solution was developed for diffusion-controlled reactions, which accounted for changes in X, p, and Cp within the combustion wave, and led to the conclusion that U< Ud(Lak-shmikantha and Sekhar, 1993). 

Based on Eq. (49), it can be concluded that for gasless combustion processes, unstable combustion is more likely to occur for higher melting temperatures. I m, in addition to higher activation energies and lower combustion temperatures (Margolis, 1992). 

Aldushin, A. P., and Merzhanov, A. G., Gasless combustion with phase transformation. Dokl. Phys. Chem., 236,973 (1978). 

Merzhanov, A. G., Rogachev, A. S., Mukasyan, A. S and Khusid, B. M Macrokinetics of structural transformation during the gasless combustion of a titanium and carbon powder mixture. Combust. Explos. Shock Waves, 26, 92 (1990a). 

Naiborodenko, Y. S., and Itin, V. I., Gasless combustion of mixtures of metal powders. I Mechanism and details. Combust Explos. Shock Waves, 11,293 (1975a). 

Rogachev, A. S., Shkiro, V. M., Chausskaya, I. D., and Shvetsov, M. V., Gasless combustion in titaniura-carbon-nickel system. Combust. Explos. Shock Waves, 24,720 (1988). 

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