Environmental Engineering Reference
In-Depth Information
C
v
,ifC
v
nR
exchange of the potential energy to work. Because k ¼
1
þ
is smaller, k is
larger. So the work A is larger.
In the evaluation of work capability of a liquid explosive, the amount of con-
densed products in detonation should be taken into consideration. If there are
condensed products in detonation, the gas products reduce relatively, and the
speci
c volume is small. In the expansion process, the gas products transform the
internal energy into work, and its temperature drops down. The process of the
internal energy from condensed products to work is that the energy of condensed
products is transferred to gases, and then transformed into work. The expansion of
gases is a fast process, in which it is dif
cult to reach the thermal balance of
condensed and gas phases. Part of the energy is still stored in the condensed phase.
This energy is
finally lost through thermal conduction. So the measured work
ability is smaller.
From the above, the explosion heat of an explosive is the conclusive parameter
of work capability; while the gas products of detonation are the medium of work.
More gas products and larger the speci
c volume, the ef
ciency of heat to work is
higher. The speci
c volume of explosives also plays an important role for the work
capability.
2.3.1.2 Evaluation of Work Capacity
(1) Measurement of work capacity using a lead cast method
The working capacity of explosives is usually measured/evaluated using lead
cast method. This method measures the increased lead-hole volume of the lead cast
in the explosion of certain explosives inside the lead hollowness. The con
guration
and effect are shown in Fig.
2.17
.
In Fig.
2.17
, the lead cast is made of
fine lead. In the center of lead cast, there is a
cylindrical hollowness with 25 mm diameter and 125 mm height. In experiments,
the measured explosive with 10
0.01 g is put in the cylindrical hollowness
(24 mm in diameter) of aluminum foil. After the detonator is installed, the
aluminum foil with detonator is put into the cylindrical hollowness of lead cast.
±
Fig. 2.17 Measurement of explosive work capacity using lead cast method. a The configuration
of lead cast before test; b the effect of lead cylinder after explosion
