Explosions theory

In the search for a better approach, investigators realized that the ignition of a combustible material requires the initiation of exothermic chemical reactions such that the rate of heat generation exceeds the rate of energy loss from the ignition reaction zone. Once this condition is achieved, the reaction rates will continue to accelerate because of the exponential dependence of reaction rate on temperature. The basic problem is then one of critical reaction rates which are determined by local reactant concentrations and local temperatures. This approach is essentially an outgrowth of the bulk thermal-explosion theory reported by Fra nk-Kamenetskii (F2). 

Adler, J. and Enig, J.W., 1964, The Critical Conditions in Thermal Explosion Theory with Reactant Consumption, Combustion and Flame 8, 97. 

The amount of explosion overpressure is determined by the flame speed of the explosion. Flame speed is a function of the turbulence created within the vapor cloud that is released and the level of fuel mixture within the combustible limits. Maximum flame velocities in test conditions are usually obtained in mixtures that contain slightly more fuel than is required for stoichiometric combustion. Turbulence is created by the confinement and congestion within the particular area. Modem open air explosion theories suggest that all onshore hydrocarbon process plants have enough congestion and confinement to produce vapor cloud explosions. Certainly confinement and congestion are available on most offshore production platforms to some degree. 

The self-heating and ignition of baled or loose wool in bulk storage is discussed and analysed, and steady state thermal explosion theory is applied to the prediction of critical masses and induction periods for storage and transportation situations in relation to ambient temperature. Results obtained were consistent with current safety practices. 

Detonation, Abel Theory of or Theory of Synchronous Vibrations. It is the earliest theory (1869). See under DETONATION (AND EXPLOSION), THEORIES, History... 

Detonation, Hydrodynamic and Hydrothermo-dynamic Theories of. See under Detonation (and Explosion), Theories of... 

In Section II of Macek s paper (Ref 13, pp 44-50) is discussed the "Thermal Explosion Theory . It will be discussed in our writeup separately. Section III contains "Transition from Deflagration to Detonation , which includes the "Precursor Shock in Solids (pp 50-2) discussed in our write-up separately, and other items. Section IV contains a brief description of Gap Test (pp 56-8) and of Impact Test (pp 58-60)... 

The aim of the thermal explosion theory is to obtain knowledge of the temperature of the system as a function of both. time and location. This can be calcd from the equation ... 

A. Ma ek, ChemRevs 62, 44-47 (1962) (Thermal decomposition of explosives including a thermal explosion theory) 14) A.M. Grishin O.M. Todes, DoklAkadN 151(2), 366-68 (1963) CA 59, 12585(1963) (Thermal explosion with heat transfer by convection and conduction) 15) P.G. Ashmore T.A.B. Wesley, "A Test of Thermal-Ignition Theory in Autocatalytic Reactions , lOthSympCombstn (1965), pp 217-226... 

The term Q is zero for the nonreaction R-H curve. These eqs are important in explosives theory. They permit correlation of the explosive characteristics of substances with other physical and chemical properties, and allow determination of the temperature and pressure conditions within the detonation zone... 

The reaction zone of NMe is too thin to be observed by the plate—velocity technique, but its presence can be inferred from other experiments. Its length was estimated to be ca 1000 A from an extrapolation of the unreacted equation of state discussed by Ilyukhin et al (Ref 64b) and the adiabatic thermal explosion theory dis cussed by Zinn Mader (Ref 64a). The pressure, p. . at the end of reaction zone which corres-ponds to the head of decay zone), was estimated to be I4lkbar, when free-surface velocity was determined using Dural plates and 135kbar when using Sierracin plate... 

From thermal explosion theory (eg see article on Hot Spots in this Vol)... 

EXPLOSION THEORIES. See under DETONATION (AND EXPLOSION) THEORIES in Vol 4, pp D601-L to D602-R. See also "Theory of Explosion Processes , N.S. Akulov, DokladyAkadNaukSSSR 104, 376—9 (1955) CA 50, 9739 (1956)... 

C-H. Yang, "The Present Theoretical Position in Explosion Theory , HthSymp-Combstn(1967), 1057—61 (18 refs)... 

A thermal explosion theory as developed by D.A. Frank-Kamenetskil (Ref 5) led to the equation AT = -[Pg.565]

The temperature rise, AT, may be made dimensionless by borrowing from thermal explosion theory. There the natural dimensionless temperature rise 6 is defined by... 

Now we must be specific about our choice of the concentration scale cref. For reasons partly based in the experiences of thermal explosion theory and partly by the desire to reduce the dimensionless equations to their simplest possible forms, we take... 

A new small-scale test has been developed which needs only a few g of thermally unstable material, which may be contained in an open cell version of the apparatus if aerobic processes are involved, otherwise in a closed cell apparatus, both with full temperature control and monitoring systems. Such materials may be divided into 2 types, depending on the behaviour of a sample after introduction into adiabatic storage at elevated temperature. The first type, which after attaining the adiabatic temperature shows a steady further increase in temperature in line with Frank-Kamenetski s thermal explosion theory, exhibit thermal combustion (TC) behaviour. In the second type, after adiabatic temperature has been reached, the sample shows a sudden rapid rate of rise, exhibiting autocatalytic (AC) behaviour as chain branching... 

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