Explosion , Energy of

Calculated relative energy of explosive released on detonation and subsequent expansion of detonation gases relative to HMX. 

Figure 9.5. Calculation of energy of explosively flashing liquids and bursts of pressure vessels filled with vapor or nonideal gas.

Calculate energy of explosion using Equation 6.3.15 in Reference 5. 

The tetraene is endothermic by some 2.5 kJ/g which is about the energy of explosion of old-fashioned black powder. 

Energy of explosion. The energy of explosion values given in Table 16.2 should be considered as the theoretical maxima, and yield factors of 10% are considered reasonable for fuel-air explosions. For equivalent volume storage, hydrogen has the least theoretical explosive potential of the three fuels considered, albeit it has the highest heat of combustion and explosive potential on a mass basis. 

The basis for this model is that the energy of explosion depends highly on the level of congestion and depends less on the fuel in the cloud. 

Appendix B contains energy of explosion values based on thermodynamic availability. 

For many materials the heat of combustion and energy of explosion differ by less than 10%, as shown in appendix B. For most practical purposes the two properties can be used interchangeably. 

D. A. Crowl, Calculating the Energy of Explosion Using Thermodynamic Availability, Journal of Loss Prevention in the Process Industries (1992), 5(2) 109-118. 

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... 

E is the energy of explosion (energy), P] is the ambient pressure (force/area),... 

The final method uses thermodynamic availability to estimate the energy of explosion. Thermodynamic availability represents the maximum mechanical energy extractable from a material as it comes into equilibrium with the environment. The resulting overpressure from an explosion is a form of mechanical energy. Thus thermodynamic availability predicts a maximum upper bound to the mechanical energy available to produce an overpressure. 

Figure 6-25 The energy of explosion for a compressed inert gas, computed using four different methods. Source D. A. Crowl and C. V. Mashuga, Understanding Explosions in the Process Industries (New York American institute of Chemical Engineers, in press) used by permission.

Determine the energy of explosion for 1 lb of gaseous n-butane. What is the TNT equivalent ... 

A standard laboratory cylinder is about 5 ft high with an internal vessel diameter of about 6 in. Determine the total energy of explosion for this cylinder if it contains nitrogen compressed to 2500 psig. Assume initial and ambient conditions of 298 K and 1 atm. 

In the TWA Flight 800 tragedy the accident is blamed on explosion of fuel vapors in the central fuel tank. The volume of the central fuel tank is 18,000 gal. a. If, at the time of the explosion, the fuel concentration in the tank is 1 % by volume and the pressure inside the tank is 12.9 psia, determine the equivalent energy of explosion for the vapor (in pounds of TNT). Assume a temperature of 80°F. Be sure to state carefully any assumptions. 

For jet fuel the energy of explosion is 18,590 Btu/lb and the molecular weight is 160. 6-30. You have decided to purchase a 500-gal tank of liquid propane (C3H8) to heat your house during the winter. You are concerned about tank rupture and the possibility of a vapor cloud explosion of all the propane. How far away (in ft) must the tank be from the house to ensure that your house will receive only minor damage from an explosion The specific gravity of liquid propane is 0.500, and the energy of explosion for propane is 503.9 kcal/g-mol. 

---