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Device
for Pressurizing Propellant Tanks
After a series of successful prototype tests we filed our first
patent application for a new Tridyne pressurization system, with a wide
commercial and military application area. The patent has been lodged
at the Swiss Federal Institute
of Intellectual Property at the 16th February. It is thought to
be flown in ASRI's
AUSROC
2.5 for the first time.
Description
During expansion of the pressurization gas into the propellant tanks
it cools down and looses a lot of its specific volume. Thus, even more
gas is needed. Tridyne uses a inert gas like helium or nitrogen enriched
with a low percentage of oxygen/hydrogen which is reacted in a catalyst
and so the Helium heats up and its volume increases. This allows to
decrease the amount of pressurization gas which saves significant weight
and space. The percentage of the Oxygen/Hydrogen in the Helium is low
enough to prevent ignition under normal conditions, it needs the catalyst.
So it is possible to safely store the whole mix in a single tank. The
catalyst consists of coated ceramic pellets with a very high internal
surface of more than 200 m2/gramm. Dependent on the content of Hydrogen
and Oxygen you can get output temperatures of several hundred degrees.
Tridyne has been invented by Rockwell in 1973 (Patent: US3779009).
The
system as described above only heats the gas which has already left
the tank. A significant amount of gas remains unused in the tank when
the lower limit of the tank pressure has reached. Due to its sub cooled
condition, the remaining gas has a significant density and therefore
useless weight. Several attempts have tried to avoid this drawback using
heat exchanger etc. (for example patent US4804520). This kind of solutions
tend to be bulky and heavy and show a slow thermal response time.
Our invention avoids the drawbacks mentioned above by using two tanks
instead of a single one:
The
system is being charged through valve 1, the gas tank 5
is therefore filled with the reactive Tridyne gas mixture. At the same
time the auxiliary tank 10 is filled through the check valve
14 and in a lower extend through the restriction 13. Both
tanks 5 and 10 have the same pressure after the loading.
The check valves 7 prevent a premature reaction of the gas mixture
in the catalyst 8 during the loading procedure and the later
storage. Through restriction 13 slow pressure changes can be
equalized e.g. caused by external heat influences. The restriction 13
is protected by fine optional filters 12 to prevent contamination.
The system is now charged and storable.
The extraction of the gas is made through valve 2. After an optional
pressure reduction in 3 the gas mixture flows into the catalyst
4 where it is reacted and therefore heated. During extraction
of the gas from tank 5 the pressure decreases and the gas cools
down. The pressure difference between tank 5 and 10 will
be equalized through the check valves 7 and the catalyst 8
where the gas coming from 10 is reacted and heated. The heated
gas flows into tank 5 through a inlet device 11 which
forces mixing. The temperature in tank 5 can be tailored by a
suitable choice of the volumes of the tanks 5 and 10.
The auxiliary tank 10, the valves 7, 13, the filters
12 and the catalyst 8 can be located outside of the tank
5. But the favourable way is to locate them inside the tank 5
where the tank 10 has to withstand only the differential pressure
between tanks 5 and 10 which leads to a lower wheight
and an easier integration of the components 7, 8, 12,
13 and 14 as well. For larger devices a cascading of the
invention is reasonable. In this case a further additional tank permits
the heating of the remaining gas in tank 10 etc. This cascading
is arbitrarily expandable. |