Environmental Engineering Reference
In-Depth Information
c.
thermal capacity of explosion product is only a function of temperature, and is
independent of the pressure (or density) during the explosion.
These assumptions could cause relatively large error in the calculation of
explosion temperature of high-density explosives.
A. Explosion temperature calculated from the average thermal capacity of
explosion products
Based on the above assumptions, the following relationship can be obtained,
Q v ¼ C v t
ð
:
Þ
3
22
where,
Q v
explosion heat of explosive,
the average thermal capacity of all explosion products at temperatures from 0
to t °
C v
C,
t
the required explosion temperature,
°
C.
The general relationship of thermal capacity with temperature is,
C v ¼ a þ bt þ ct 2
þ dt 3
þ
ð
3
:
23
Þ
rst two are
chosen, which means that thermal capacity and temperature have a linear rela-
tionship, thus,
Generally, in calculations that are not too complicate, only the
C v ¼ a þ bt
ð
3
:
24
Þ
According to Eq. 3.22 , the following can be obtained,
Q v ¼ C v t ¼ a þ bt
ð
Þ t
ð
3
:
25
Þ
bt 2
þ at Q v ¼
0
Therefore, the explosion temperature is,
p
a 2
t ¼ a þ
þ
4bQ
v
ð
3
:
26
Þ
2b
When this method is used to calculate explosion temperature, explosion reaction
equations, ingredients of explosion products and thermal capacity of explosion
products must be known. In the calculation, thermal capacity of explosion products
can be that of their gas molecules as listed in Table 3.11 .
Thermal capacity values in Table 3.11 are good at 4,000
°
C or below, but the
experimental temperature for these data is 2,500
C. Thus, its extrapolated
temperature is too high and the necessary correction should be done. Additionally,
Al 2 O 3 is only useful at a temperature of 0
3,000
°
-
1,400
°
C.
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