Re: Cortank

On Fri, 08 Dec 2006 15:16:27 +0000, Mishagam wrote:

Togtilt wrote:
Bill Ward wrote:
On Wed, 06 Dec 2006 21:52:57 -0800, Togtilt wrote:

While many competent posters in this group hold out no hope for a
hydrogen economy, there is probably going to be some level of
experimentation, which leads to the question of how to efficiently
transport hydrogen without dedicated pipelines. Moving LH2 by truck,
the present method, uses a truck and tank that is more than ten times
the weight of its payload, and liquifying the H2 uses almost 40% the
energy inherent in the H2. What about the possibility of transport by
airship. A core 'tank' could be pressurized to four or five
atmospheres and still offer some lift. This tank might take up 25-30%
of the volume of the airship. The remaining volume could hold H2 at
ambient pressure; adding or removing H2 from both containments at a
proportional rate could maintain neutral bouyancy. Even an airship
that is small by the hindenburg standard, maybe 100 ft in diameter by
500 ft long, could ship over ten tons, and do so to any remote
location....the most likely place for consumers of this exotic fuel.
Perhaps a tubular frame could be pressurized with nitrogen, to serve
as a resovior for gas panels that would form a protective inert gas
hull. Additional N2 could be derived from the exhaust of the airships
engines.
Interesting idea, but one of the main problems with large rigid frame
dirigibles is that they do not handle wind shear very well. The US
Navy lost two big ones in severe weather, and lost interest. Maybe
newer materials and methods would help, but the forces involved can be
immense.

Regards,

Bill Ward


Just a few points.
The Shenandoah was lifted by a squall to above its pressure altitude,
after its vents had been sealed shut. The overinflated gas bags broke
the frame. The Akron ran its tail into the atlantic during a storm. The
Macon had a ring frame supporting an elevator fin buckle in crossing the
rockies at 6000 ft. The makeshift repair failed off the coast of big
sur and tore a hole that released helium and filled with rain.
Compressing H2 takes less than 1% of the energy inherent in the gas
compressed.
The material weight of the 'tank' relative to the mass of the gas
enclosed will be roughly constant, no matter what the pressure. The
rigidity of the pressurized tank could serve as a structural component.
Unlike a plane or truck, the return trip will not be somewhat more
efficient as the airship will still have to be neutrally bouyant with
ballast or reduced lifting gas.
Like ocean tankers, efficiency increases with scale, the cube root of
the volume. An efficient tanker would probably have to be larger than
the hindinburg.
Still, it might make sense for a tanker that carrys a cargo that's
lighter than air to be a lighter than air airship. It's also true that
H2 is a very big round peg that dosn't fit into the round hole that
conventional fuels are transported through, but if shipping H2 is the
question, the durigible should not be ruled out.

How much you think very large tank pressurized to 4-5 atmospheres would
weight? When tank becomes larger it's walls have to become proportionally
stronger. Car tires I think hold pressure in this range - so if you have
tank 100 times wider than car tire (100 ft to 1 ft) - you have to have
proportionally wider walls - about 1 meter if of the same material as
tires, may be less - but tires cord is made from strong polymer of steel
fibers - basically the same material as your tank - so you tank possibly
will be about as strong as tires. On the other side, big pressurized to
4-5 atmospheres tank would be VERY rigid - and probably can do without any
external frame.

The next problem would be what to pressurize it with on the return trip.
Air would be too heavy. Maybe it could be used as a demonstration
project, flying H2 around the country to show how easy it is. Then it
could always be full.

Bill Ward
.

Relevant Pages

  • Re: Cortank
    ... A core 'tank' could be ... tank might take up 25-30% of the volume of the airship. ... resovior for gas panels that would form a protective inert gas hull. ... The Shenandoah was lifted by a squall to above its pressure altitude, ...
    (sci.energy.hydrogen)
  • Re: Cortank
    ... A core 'tank' could be ... tank might take up 25-30% of the volume of the airship. ... resovior for gas panels that would form a protective inert gas hull. ... The Shenandoah was lifted by a squall to above its pressure altitude, ...
    (sci.energy.hydrogen)
  • Re: Cortank
    ... A core 'tank' could be pressurized to four or five ... of the volume of the airship. ... as a resovior for gas panels that would form a protective inert gas ... The Shenandoah was lifted by a squall to above its pressure altitude, ...
    (sci.energy.hydrogen)
  • Re: Cortank
    ... A core 'tank' could be ... tank might take up 25-30% of the volume of the airship. ... resovior for gas panels that would form a protective inert gas hull. ... The Shenandoah was lifted by a squall to above its pressure altitude, ...
    (sci.energy.hydrogen)
  • Re: Cortank
    ... A core 'tank' could be ... tank might take up 25-30% of the volume of the airship. ... resovior for gas panels that would form a protective inert gas hull. ... The Shenandoah was lifted by a squall to above its pressure altitude, ...
    (sci.energy.hydrogen)
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