Environmental Engineering Reference
In-Depth Information
Table 2.1 Released energy comparisons of various fuels
Materials
Explosion heat
(kJ/kg)
Mixtures with air
(kJ/kg)
Mixtures with
air (kJ/L)
Wood
18,828
7,950
19.7
Coal
33,472
9,205
17.99
Gasoline
41,840
9,623
17.6
Black powder
2,929
2,929
2,803
Nitrotoluene (TNT)
4,184
4,184
6,485
Nitroglycerine (NG)
6,276
6,276
10,042
Octogen (HMX)
5,530
5,530
10562.3
Hexanitrohexaazaisowurtzitane
(CL-20)
6,028
6,028
12319.4
All above reactions are the decomposition of citrates and have similar products. In
decomposition processes, their exothermicities are different. All citrates with endo-
thermic decomposition reaction are not explosive materials. Only silver citrate and
mercury citrates with exothermic decomposition reaction are explosive. Although
copper citrate has exothermic decomposition reaction, the heat is too less compared to
the general explosive materials. Copper citrate can cause explosion, but a weak
explosion. However, the heat released in explosion from explosive materials is
probably not much. If counted in unit weight, this heat is probably lower than fuels.
Why explosive materials can have violent explosion? Because explosive materials
release more energy in unit volume, and the energy density is very high. Table
2.1
shows the comparison of released energy by different materials.
Table
2.1
indicates that the energy/heat released by explosive materials per unit
kilogram is much lower than that by fuels, just part of the energy/heat that fuels
release in combustion. The density of air is very low compared to fuels and
explosive materials. But the energy/heat of explosive materials is about 130
600
times that of fuels. The energy of explosive materials is concentrated, and energy
density is higher.
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2.1.2 Rapid Reaction of Liquid Explosive Materials
The second necessary condition of explosions is the rapidity of reactions, which
differentiates the general chemical reactions and explosions. Explosive materials per
unit weight have less energy than fuels. However, the combustion of general fuels
per unit weight has more energy/heat than explosive materials. These combustion
reactions plod slowly. The energy aggregation and release conduct in a rapid speed.
Rapidity of energy release is one of the most obvious features of explosion. Per
kilogram coal releases 25,940 kJ after complete combustion. While per kilogram
nitroglycerine only has 6213.2 kJ. The energy from per kilogram coal is about 4.175
times than that of nitroglycerine. The complete combustion of 1-kg coal needs
