Environmental Engineering Reference
In-Depth Information
In the deduction of the explosive combustion, study of liquid and solid explo-
sives separately is not a must. When heat is transferred to the solids, they start to
liquefy. And the liquids follow the above combustion rules. Figure
2.2
indicates
that the combustion of condensed explosives is similar to that of
flammable gases
under steady condition. The only difference is that for gas combustion all mixtures
are gases while the gases are obtained by evaporation of liquids.
From the above analysis of volatile explosives, it is concluded that the mass
speed of combustion equals the evaporation speed of liquids (Eq.
2.6
).
fl
q
u ¼
q
1
u
n
ð
2
:
6
Þ
Here, u is the linear speed of evaporation;
ˁ
is the density of explosives; u
n
is the
normal speed of evaporation
q
1
is the density of evaporation.
According to the equation of evaporation
combustion;
-
-
combustion, the mass combustion
speed of evaporation is Eq.
2.7
.
s
2
n
þ
1
q
RT
1
E
Þ
n
n
þ
q
u ¼
ð
T
1
T
0
ð
1
Þ!
WT
ðÞ
ð
2
:
7
Þ
Here, T
1
is the temperature of combustion; WT
ðÞ
is the reaction speed at T
1
; q is
the heat of combustion;
ʻ
is the thermal conductivity of evaporations; n is the
reaction order.
If the combustion is the
first-order reaction, the mass combustion speed of
volatile explosives is written in Eq.
2.8
.
s
k
qT
1
T
0
2
RT
2
E
q
u ¼
Þ
q
2
Ae
E
=
RT
ð
2
:
8
Þ
ð
Here,
q
2
is the evaporation density at T
1
; A is the preexponential factor.
The second equation of mass combustion speed is Eq.
2.9
.
s
2
n
þ
1
RT
1
E
q
Þ
n
n
þ
Þ!
DP
n
e
E
=
RT
q
u ¼
ð
T
1
T
0
ð
1
ð
2
:
9
Þ
Here, DP
n
e
E
=
RT
is the reaction speed of several orders; n is the reaction order;
D is the scale factor.
Equation
2.9
can be rewritten in Eq.
2.10
.
s
2
n
þ
1
p
P
n
q
RT
1
E
Þ
n
n
þ
1
q
u ¼
ð
T
1
T
0
ð
Þ!
De
E
=
RT
ð
2
:
10
Þ
