Environmental Engineering Reference
In-Depth Information
first stage is the exothermic reactions of the condensed phase. The reactions
proceed on the surface or close to the surface. Because the reactions are in progress
in the condensed phase, pressure does not impact a lot for the react rates, but
temperature does. This reaction space is the condensed zone.
The second stage is the reactions of products from the
The
first stage, and the reaction
space is the gas phase intermediate reaction zone. The released heat from second
stage is transferred to the condensed phase, and accelerate the reactions in the
condensed phase.
The third stage occurs in the place, which is certain distance from the surface of
condensed phase. The products from the second stage react violently. The reactions
release a lot of heat,
final combustion products are
engendered. Passing through intermediate reaction zone,
fl
ames are generated, and
the released heat
is
transferred to the condensed phase.
In the second stage, the temperature is relatively low, and the color of the
intermediate reaction zone is dark blue. It is also named as
flameless reaction zone.
In stable/steady combustion, the combustion speed of liquid explosives has a
relationship of Eq.
2.18
with pressure.
fl
u ¼ a
þ
bP
v
ð
2
:
18
Þ
Here, u is the linear speed of combustion reactions; a is a constant which is
determined by the reactions in condensed phase and the thermal conductivity; b is a
coef
cient which is determined by reactions in gas phase; v is an index which is
determined by the reaction order of dominant reactions in gas phase.
Overall, for nonvolatile liquid explosives, proportion of reactions in condensed
phase is the dominant at low pressure; the reactions of
flame zone is the main stage
at high pressure; while both reactions in condensed phase and
fl
fl
ame zone works
comprehensively.
2.2.1.4 Combustion of Fast-Burning Liquid Explosives
The combustion/burning speeds/rates of explosives are related to their evapor-
ability. When the explosives are dif
cult to vaporize, the reactions in condensed
phase take a large proportion. H
2
O
2
-azidoethane is a traditional/classic explosive
which is dif
cult to vaporize. In the combustion of H
2
O
2
-azidoethane, the reactions
in condensed phase are faster. They released a lot of gas products and heat burst the
surface of condense phase violently. Then the gas products and some reactants go
into gas phase directly and the reactions continue. The reactions terminate in the
zone which is a little far from the intersurfaces. Under certain pressure and tem-
perature, this preheating zone is
fixed. The surface bursting of the condensed phase
occurring with the vaporization together increases intersurface area and accelerates
