Environmental Engineering Reference
In-Depth Information
Therefore, energy and state equation of the material can be closely correlated as
the following:
Q
V
¼
Q
P
þ
nPV
ð
3
:
9
Þ
or
Q
V
¼
Q
P
þ
nPV
ð
3
:
10
Þ
where,
n
the number of moles of gas products from explosion,
V
molar volume of gas.
At 18
°
C or 291 K, they are the following,
Q
V
¼
Q
P
þ
nPV
ð
3
:
11
Þ
Q
V
¼
Q
P
þ
nPV
ð
3
:
12
Þ
The above two equations showed the relationship of explosion gas with constant
volume to that with constant pressure. In the design calculation of explosive thermal
effects,
some further
simpli
cations can be made based on the speci
c
circumstances.
3.2.1 Design Calculation of Properties and Their Factor
Relationship of Liquid Explosive
3.2.1.1 Calculation of Explosion Heat
Explosion heat of explosive can be determined experimentally, and can also be
calculated with theoretical methods in the design of its formula. During the cal-
culation of explosion heat with theoretical method, chemical composition, explo-
sive reaction equations, and required thermochemical data of
the designed
explosive must be known
first, then the empirical approach Hess law can be used
for the calculation.
“
Thermal effect of reaction, not related to the reaction pathway, is only related to
the initial state and the
final state of the system
”
is the core of Hess Law. In other
words,
final product with different
pathways, sums of the released or absorbed heat should be equal to each other.
During the design calculations of explosion heat, the following triangle (Fig.
3.3
)
could be used to explain. As shown in the
if the same substance turns into the same
gure, State 1 corresponds to the state
elemental composition of explosive, State 2 corresponds to explosive itself, and
