Constant volume explosion

As was already mentioned, experimental determinations of heat of explosion and of heat of detonation are conducted in steel or special alloy cylindrical vessels of strong construction, known as "constant volume explosion bomb calorimeters and as "detonation calorimeters . To the brief description of such calorimeters (bombs), which is given in Vol 2 of Encycl, p Cll-R, the following may be added ... 

Fig 25(a) Pentolite, Centrally Detonated Fig 25 (c) Pentolite Constant Volume Explosion,... 

This value is the constant-volume explosion thermal effect of a mixture of ammonium nitrate (11.35 mol) and TNT (1 mol). 

With J/g as the unit, constant-volume explosion heat of Amatol is the following 4748.38 X 1000... 

The pressure/impulse diagrams in Fig. 10.8 illustrate the respective changes recorded for a detonation (line 1), a constant volume explosion (line 2) and a deflagration with 200 m/s velocity (line 3) and 150 m/s (line 4). Accounting for the finite duration of the blast wave is of crucial importance because of the potential reduction of dangerous distances. 

Fig. 10.8 Diagram of blast wave pressure/impulse resulting from H2 + air cloud explosion ( H2 - 100 kg) for various combustion modes line 1 - detonation line 2 - constant volume explosion line 3 — deflagration with 200 m/s velocity line 4 - deflagration with 100 m/s velocity 5 - boundary of deflagration regimes...

Such hot spots react instantaneously as localized, constant volume sub-explosions (Urtiew and Oppenheim 1966 Lee and Moen 1980). If the mixture around such a sub-explosion is preconditioned sufficiently to ignite on shock compression, a detonation wave will engulf the entire process of flame propagation. 

Four methods are used to estimate the energy of explosion for a pressurized gas Brode s equation, isentropic expansion, isothermal expansion, and thermodynamic availability. Brode s method21 is perhaps the simplest approach. It determines the energy required to raise the pressure of the gas at constant volume from atmospheric pressure to the final gas pressure in the vessel. The resulting expression is... 

By modifying the procedure described above to explode a wire in the water sphere while the system was under compression, they did attain explosions. Measuring the rebound of the cylinder and the loss of aluminum, they could estimate the work produced by the event. Assuming the maximum energy transfer to the water would occur by constant volume heating to the aluminum temperature, foUowed by an isothermal, reversible expansion, they estimated an efficiency of about 25%. Clearly the exploding wire led to an immediate and effective dispersal of the water. 

Hayes (1938) Measurement of Grains (pp 28-29) Compression Test (29) Stability by Kl-Starch Paper Test, 134.5°C Heat Test, 120°C Heat Test, 65.5°C Surveillance Test and Observation Test (29-30) Ballistic Test (30-31) Heat of Explosion at Constant Pressure (51-2) Volume of Gas (52-3) Heat of Explosion at Constant Volume (54-5) Potential (55) Temperature of Explosion (55-7) Pressure of Explosion (57-61) Heat of Explosion of Propellants (62-4) Ignition of Propellants (68-70) Mode and Rate of Burning (70-71) Velocity Measurements by Le Boulange, Aberdeen, and Solenoid Chronographs (84-92) Pressure Measurements by Crusher and Piezoelectric Gages (92-6)... 

Heat of Detonation is defined by Dunkle (Ref 40, p 248) as the "heat liberated at calorimeter temperature when an explosive detonates at constant volume and with no change in the product composition from that which was obtained at C-J point. Heat of detonation can be calculated from heat of explosion, or a closer experimental approach can be attempted by detonating the sample at high density and under strong confinement"... 

Detonation (and Explosion), Temperature Developed On. It may be defined as the maximum temperatures developed on detonation and explosion and must not be confused with Detonation (and Explosion) Temperature described in previous item A. Calculation of Temperature of Detonation (or Explosion). The oldest and simplest method is based on the assumption that expln is an adiabatic process taking place at constant volume and that the heat evolved (Qv), is used exclusively for heating the products of expln. Another assumption is that temp can be calcd by. dividing the heat of expln by specific heats of the products of expln ... 

For purposes of this calculation, latent heats at constant volume and at constant pressure are assumed equal, heat capacities at constant pressure and at constant volume are assumed equal for solids and liquids [See also Calculation of Temperature of Detonation (and Explosion) 1 and Experimental Determination of Temperature of Detonation [and Explosion) , under Detonation (and Explosion) Temperature Developed On in Vol 4 of Encycl, pp D589 L to D601-R]... 

The power or strength of an explosive is a measure of its ability to do useful work. This is also termed the potential of an explosive and is the total quantity of heat given off by an explosive at constant volume. The volume of gas (V) and heat of explosion (Q) can be calculated independently. The explosive power of an explosive is then obtained on multiplying Q with V that is, (Equation 1.15) ... 

Energy vs Velocity of Deflagration of Colloidal Propellants. Accd to Muraour Aunis (Ref) the energy Q, in keals liberated at constant volume by decompn of 1kg of prop-lnt (or explosive) is shown graphically to be... 

When an explosive is initiated either to burning or detonation, its energy is released in the form of heat. The liberation of heat under adiabatic conditions is called the heat of explosion, denoted by the letter Q. The heat of explosion provides information about the work capacity of the explosive, where the effective propellants and secondary explosives generally have high values of Q. For propellants burning in the chamber of a gun, and secondary explosives in detonating devices, the heat of explosion is conventionally expressed in terms of constant volume conditions Qv. For rocket propellants burning in the combustion chamber of a rocket motor under conditions of free expansion to the atmosphere, it is conventional to employ constant pressure conditions. In this case, the heat of explosion is expressed as Qp. 

Under constant volume conditions Qr can be calculated from the standard internal energies of formation for the products Al/f (productS) and the standard internal energies of formation for the explosive components AUf (explosive components) as shown in Equation 5.4. 

In considering the thermochemistry of solid and liquid explosives, it is usually adequate, for practical purposes, to treat the state functions AH and A U as approximately the same. Consequently, heats, or enthalpy terms, tend to be used for both constant pressure and constant volume conditions. 

Table 5.12 Heat of explosion and heat of detonation at constant volume for some primary and secondary explosive substances using the K-Wand modified K-W rules. AHf (H20) is in the gaseous state...

The temperature of explosion Te is the maximum temperature that the explosion products can attain under adiabatic conditions. It is assumed that the explosive at an initial temperature Tt is converted to gaseous products which are also at the initial temperature T,. The temperature of these gaseous products is then raised to Te by the heat of explosion Q. Therefore the value of Te will depend on the value of Q and on the separate molar heat capacities of the gaseous products as shown in Equation 5.14, where Cv is the molar heat capacities of the products at constant volume and E represents the summation of the heat capacity integrals corresponding to the separate components of the gas mixture ... 

In calculating the heat of explosion we assumed that the temperature of explosion Tt was 4000 K. If this assumption was correct then the heat liberated by the explosion at 4000 K should equal 1149 kJ mol-1. The calculated value for the heat liberated, where the initial temperature is taken as 300 K, is presented in Equation 6.12. The values for the mean molar heat capacities at constant volume can be found in Table 5.15. 

Contact above 0°C of excess chlorine or a chlorinating agent with aqueous ammonia, ammonium salts or a compound containing a hydrolysable amino-derivative, or electrolysis of ammonium chloride solution produces the highly endothermic (AHf (g) +230.1 kJ/mol, 1.91 kJ/g) and explosive nitrogen trichloride as a water-insoluble yellow oil [1,2,3]. Detonation at constant volume generates 5,500 Bar maximum pressure and 2,100°C maximum temperature. As a vapour it decomposes explosively at pressures as low as 1 mBar and may sensitise flammable gas mixtures even as a... 

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