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High strength fibers for high pressure tubes.

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Robert Clark

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Apr 22, 2005, 3:27:13 PM4/22/05
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I have interest in an application involving a very high pressure tube.
The pressure a pipe can resist is given by the Barlow formula P =
2*S*t/d, with P the pressure, S the tensile strength of the pipe
material, t the pipe wall
thickness, and d the inner diameter.
I want to get maximum pressure resistance for the weight of the tube
for my
application. However, if the tube is made of wound fibers such as
carbon fibers, Kevlar fibers, S-glass fibers etc., you won't have the
same tensile strength of the pipe wall material as that of the fibers
in longitudinal tension, which can be in the range of 1,000,000 psi.
This is because the fibers have to be bound together with epoxy which
will reduce the tensile strength of the pipe wall against burst
pressures (BTW, how much is this reduction in comparison to the
longitudinal tensile strength of the fiber?)
So I was thinking, has anyone tried drilling through these fibers
longitudinally to create tubes? Since the fibers are quite thin this
would
create quite thin tubes, but that's alright for my application as I can
just
bind them together to get more fluid flow.
The question is would the tensile strength circumferentially be the
same as
the tensile strength for the fibers tensed longitudinally?
A couple of ideas occur to me. While forming the fiber you could have
it form around a thin rod covered with some type of lubricating
material so
that after the fiber forms, you could slide out the rod to get a hollow
fiber.
Or you could have this rod have a much lower melting or sublimation
temperature than your fiber and raise the temperature so the rod will
melt or
sublimate then flush the melted or gaseous rod material from within the
fiber.
Secondly, to test the fibers circumferential tensile strength without
having
to make the fibers be hollow, you could drill a small hole cross-wise
through
the fiber. Then send a high pressure fluid through the small hole. You
could
deduce the cross-wise tensile strength from the Barlow formula by
seeing how
high the pressure can be before the fiber fails cross-wise.


Top view:


-----------------------------------------------

___ ^
/ \ |
| | Cross-wise tensile strength to be tested.

\___/ |
v

-----------------------------------------------

Tensile strength<------------->known high lengthwise.


Side view:

Hole drilled downwards through fiber this way:
|
| And high pressure fluid sent downwards through
hole.
v


-----------------------------------------------

^
|
Cross-wise tensile strength to be tested.
|
v

-----------------------------------------------

(Hole drilled cross-wise, so not visible from side.)

In addition to the application I'm considering which is aerospace
related,
a potentially very important application to this would be in hydrogen
storage.
Hydrogen fueled automobiles have been given high priority by the US
government. A key problem that needs to be solved is the storing of the
hydrogen in low weight systems within the vehicles. The US government
has set
a benchmark of 6.5% weight hydrogen to the storage system weight for
hydrogen
fueled vehicles to be competitive with gasoline vehicles.
Liquid hydrogen requires expensive and heavy cryogenics. And gas
hydrogen
storage requires the gas to be kept at high pressures.
In the case of gas storage clearly you want the density to be as high
as
possible while at the same time saving weight in the storage system.
This is
why high tensile strength materials would be useful.
Carbon nanotubes have been a key area of research in this regard.
There were
some early reports that high storage density was achieved but these
results
were not repeatable:

Carbon nanostructures: An efficient hydrogen
storage medium for fuel cells?
http://www.fuelcelltoday.com/FuelCellToday/FCTFiles/FCTArticleFiles/Article_433_Carbon%20Nanostructures.pdf

In addition to the high strength non-metallic fibers mentioned above
there is also
a high strength steel wire marketed known as Scifer wire. This steel
wire can
be up to 5.5 Gpa strong in tension. As is the case with the other
fibers this strength
holds in longitudinal tension for thin wires: the Scifer wire may be
only 8 microns
wide. However, interestingly there is micromaching being done actually
at the
*submicron* scale. Here's a review article by Clark-MXR, Inc. (no
relation) :

Clark-MXR, Inc. Femtosecond Lasers Micromachining Handbook.
http://www.cmxr.com/Industrial/Handbook/Introduction.htm

The key facet that makes this possible is that ultrafast laser pulses
are
used. This prevents the thermal energy from spreading beyond the area
that
needs to be machined.
This method clearly would suffice for creating a small hole cross-wise
in
8 micron wide wires or wider fibers, which would allow tests to be
made of their
cross-wise tensile strength.
In regard to producing tubes from the wire, the method may also work
if the
wire is kept very straight. Also, an interesting advantage of using
ultrafast
pulses is that the heated material moves away quickly from the
illuminated
area because it turns into a highly ionized plasma. We might also help
this
process by using a high pressure suction to remove this material or
high
magnetic fields.
Still another facet of these ultrafast lasers is that they can
actually be
tuned to focus *inside* the material. That is, the exterior of the
material
is left unheated and the laser energy is concentrated inside.

We can get an estimate of the storage weight density of hydrogen we
can achieve using
Scifer steel tubes assuming they are able to maintain their 5.5 Gpa =
55,000
bar tensile strength radially. At very high pressure hydrogen like all
gases
no longer obeys the ideal gas law. I found this page that computes
hydrogen
properties given temperature and pressure:

Hydrogen Properties Package.
http://www.inspi.ufl.edu/data/h_prop_package.html

Lets say we store the hydrogen at 2200 bar. Then at 200K the density is
62.4
kg/m^3. Use the Barlow formula to see how thick the Scifer steel tube
would
have to be to hold a gas at 2200 bar pressure: P = 2*S*t/d, t =
P*d/(2*S) =
2200*d/110000 = d/50 . Since the outside diameter = 8 microns = d +
2*t, this
results in t = .154 microns and d = 7.7 microns. For say a 1 meter long
tube
the volume of the steel would be Pi*(.000008^2-.0000077^2)/4 =
3.7*10^(-12)
cubic meters. At 7800 kg per cubic meter density for steel this would
weigh
2.89*10^(-8) kg.
Now the hydrogen inside the tube would have volume Pi*.0000077^2/4 =
46.57*10^(-12) cubic meters and at 62.4 kg/m^3 density would weigh
2.91*10^(-9) kg. So the ratio of the hydrogen to the steel would be
2.91*10^(-9)/28.9*10^(-9) = .1, which exceeds the benchmark required
for
hydrogen car viability.
Actually looking at the density numbers returned by the "Hydrogen
Properties
Package" we could do better than this by choosing a lower pressure for
the
hydrogen. And indeed the pressure probably doesn't have to be
exorbitant. But
the key factor is of the thinness of the Scifer steel or other high
strength fiber
that would be required to hold it.

Bob Clark

G. R. L. Cowan

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Apr 22, 2005, 5:06:09 PM4/22/05
to

For tiny tubes with walls that ought to be fairly strong,
see http://www.caer.uky.edu/energeia/PDF/vol6-3.pdf ,
figure 6.


--- Graham Cowan, former hydrogen fan
http://www.eagle.ca/~gcowan/Paper_for_11th_CHC.html --
boron: how individual mobility gains nuclear cachet

Uncle Al

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Apr 22, 2005, 4:59:37 PM4/22/05
to
Robert Clark wrote:
[snip]

> Since the fibers are quite thin this
> would
> create quite thin tubes, but that's alright for my application as I can
> just
> bind them together to get more fluid flow.

[snip]

Unclear on the concept. Viscous conductance varies as (radius)^4.

> We can get an estimate of the storage weight density of hydrogen we
> can achieve using
> Scifer steel tubes

[snip]

Hopeless idiot. The H*Y*D*R*O*G*E*N car is bullshit. The densest
storage of hydrogen, atoms/liter, is diesel - and you can do that in
an open bucket without paying for /_\PV.

--
Uncle Al
http://www.mazepath.com/uncleal/
(Toxic URL! Unsafe for children and most mammals)
http://www.mazepath.com/uncleal/qz.pdf

Philip Holman

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Apr 22, 2005, 6:36:30 PM4/22/05
to

"Robert Clark" <rgrego...@yahoo.com> wrote in message
news:1114198033.4...@g14g2000cwa.googlegroups.com...

>I have interest in an application involving a very high pressure tube.
> The pressure a pipe can resist is given by the Barlow formula P =
> 2*S*t/d, with P the pressure, S the tensile strength of the pipe
> material, t the pipe wall
> thickness, and d the inner diameter.
> I want to get maximum pressure resistance for the weight of the tube
> for my
> application. However, if the tube is made of wound fibers such as
> carbon fibers, Kevlar fibers, S-glass fibers etc., you won't have the
> same tensile strength of the pipe wall material as that of the fibers
> in longitudinal tension, which can be in the range of 1,000,000 psi.
> This is because the fibers have to be bound together with epoxy which
> will reduce the tensile strength of the pipe wall against burst
> pressures (BTW, how much is this reduction in comparison to the
> longitudinal tensile strength of the fiber?)

Hoop stress is double longitudinal stress for a pressurized tube. High
pressure hoses have bias plies at an angle of ~65deg. to the
longitudinal axis. This way the plies are not in shear. Car and bicycle
tires are at 45 deg. to constrict the wheel on inflation. Inflating a
tubular tire to max pressure off the rim will damage the tire.

Phil H


Robert Clark

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Apr 22, 2005, 10:04:52 PM4/22/05
to

Uncle Al wrote:
> Robert Clark wrote:
> ...

> Hopeless idiot. The H*Y*D*R*O*G*E*N car is bullshit. The densest
> storage of hydrogen, atoms/liter, is diesel - and you can do that in
> an open bucket without paying for /_\PV.
>
> --
> Uncle Al

"Dr. Strange Al, or how I learned how to stop worrying and love
pollution."

Reading Al's posts on this topic you get the feeling he doesn't WANT
cars to run on pure hydrogen even if it is feasible to do so.

Bob Clark

G. R. L. Cowan

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Apr 22, 2005, 10:20:34 PM4/22/05
to

http://www.hydrogen.org/h2cars/overview/main01.html

That's a lot of prototypes, and a lot of years, for zero sales.

Robert Clark

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Apr 22, 2005, 10:10:29 PM4/22/05
to

G. R. L. Cowan wrote:
>...

> For tiny tubes with walls that ought to be fairly strong,
> see http://www.caer.uky.edu/energeia/PDF/vol6-3.pdf ,
> figure 6.
>
>
> --- Graham Cowan, former hydrogen fan
> http://www.eagle.ca/~gcowan/Paper_for_11th_CHC.html --
> boron: how individual mobility gains nuclear cachet


I couldn't get that link to open. Is it still up?


Bob Clark

Dan Bloomquist

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Apr 22, 2005, 10:13:16 PM4/22/05
to

Robert Clark wrote:

> Uncle Al wrote:
>
>>Robert Clark wrote:
>>...
>>Hopeless idiot. The H*Y*D*R*O*G*E*N car is bullshit. The densest
>>storage of hydrogen, atoms/liter, is diesel - and you can do that in
>>an open bucket without paying for /_\PV.
>

> "Dr. Strange Al, or how I learned how to stop worrying and love
> pollution."
>
> Reading Al's posts on this topic you get the feeling he doesn't WANT
> cars to run on pure hydrogen even if it is feasible to do so.

Feasible and practical are not the same concept. Arnold Schwarzenegger
gets 50 miles of range with his new H2 Hummer. (And I'll bet he has to
keep his foot out of it for even that.) How much did that vehicle and
fuel cost? And the big question that never seems to get addressed,
'Where does the hydrogen come from?'

> Bob Clark

Best, Dan.

Robert Clark

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Apr 22, 2005, 10:34:28 PM4/22/05
to

Feasible, practical, cost effective, cheaper. Dr. Strange Al still
wouldn't like it as long as it *didn't* create pollution.


Bob Clark

Dan Bloomquist

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Apr 22, 2005, 11:21:47 PM4/22/05
to

Robert Clark wrote:

> Dan Bloomquist wrote:
>
>>Robert Clark wrote:
>>>
>>> Reading Al's posts on this topic you get the feeling he doesn't
>
> WANT
>
>>>cars to run on pure hydrogen even if it is feasible to do so.
>>
>>Feasible and practical are not the same concept. Arnold
>
> Schwarzenegger
>
>>gets 50 miles of range with his new H2 Hummer. (And I'll bet he has
>
> to
>
>>keep his foot out of it for even that.) How much did that vehicle and
>
>
>>fuel cost? And the big question that never seems to get addressed,
>>'Where does the hydrogen come from?'
>>

> Feasible, practical, cost effective, cheaper. Dr. Strange Al still
> wouldn't like it as long as it *didn't* create pollution.

You didn't answer my question. It goes directly to the 'create
pollution' issue. Where does the hydrogen come from? Answer this instead
of making claims about what Uncle Al would like.

Making a case based on your feelings has no credibility on a sci group.

> Bob Clark

Best, Dan.

CWatters

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Apr 23, 2005, 3:38:55 AM4/23/05
to

"Robert Clark" <rgrego...@yahoo.com> wrote in message
news:1114198033.4...@g14g2000cwa.googlegroups.com...
> So I was thinking, has anyone tried drilling through these fibers
> longitudinally to create tubes? Since the fibers are quite thin this
> would create quite thin tubes,

Wouldn't you loose a lot of energy getting anything to go through tubes that
small?


mme...@cars3.uchicago.edu

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Apr 23, 2005, 3:50:02 AM4/23/05
to
No, just that he doesn't consider it to be very feasible to do so, the
delusions of enthusiasts notwithstanding.

Mati Meron | "When you argue with a fool,
me...@cars.uchicago.edu | chances are he is doing just the same"

G. R. L. Cowan

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Apr 23, 2005, 8:02:06 AM4/23/05
to

They both seem all right now. Maybe caer.uky.edu
had a brief spell of pining for the fjords.

Robert Clark

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Apr 23, 2005, 8:27:40 AM4/23/05
to

Really, Mati? We already have light-weight tanks that can hold 10,000
psi. And we have materials that can withstand 1,000,000 psi at least in
one direction. Does it really seem so unimaginable that we can increase
this pressure to 30,000 in light-weight tanks or find materials that
have 1,000,000 psi strength isotropically as a technical problem? Like
trying to find the answer to nuclear fusion?
Note also that we already have methods for creating gem-quality
diamonds in millimeter sized amounts and diamond probably has strength
isotropically at least 1 Mbars = 15,000,000 psi. The methods for
creating these large-sized diamonds can clearly be scaled up so as a
technical problem it is feasible.
No, in reading his posts the implication you draw is that he doesn't
like any idea that was specifically designed to *reduce* pollution.


Bob Clark

Robert Clark

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Apr 23, 2005, 8:31:55 AM4/23/05
to

Short answer: I don't know. I am not a hydrogen "enthusiast". I was
only giving a proposed solution to a problem that is having millions of
dollars world-wide spent yearly on it.

Bob Clark

Robert Clark

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Apr 23, 2005, 8:37:56 AM4/23/05
to

Good question. It *might* be that the increased pressures you can hold
will allow you to maintain high flow-rates. Another consideration is
that the friction/viscosity reduction is dependent on the smoothness of
the material. This is unknown for holes drilled through the centers of
these high strength fibers/wires.


Bob Clark

G. R. L. Cowan

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Apr 23, 2005, 9:31:42 AM4/23/05
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Maybe I missed something, but I believe Arnold has still converted
zero Hummers. GM converted one, and staged a mockery of a travesty
of a sham where a hose was put in this hummer, connected to a dummy
hydrogen pump, held by an actor playing the governor. No hydrogen
was transferred.

jbuch

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Apr 23, 2005, 9:39:03 AM4/23/05
to


Scientific American recently ran an article on the unlikelyhood of the
HYDROGEN economy showing up for quite a while.

Do you read any such technical appraisals ... ? Or do you just read the
HYDROGEN WILL SAVE US .... sorts of things.

I think it was Fortune magazine that just last month had an article on
the General Motors thrust to HYDROGEN as one ofthe future ways to save
the company, and it described the many problems to this ever being realized.

Popular Science magazine is famous for the flying car-airplane articles
from the 1950's and 1960's as well as the personal helicopter articles
of the same period.

They also were big on air conditioning based merely on clever
compression and expansion of the air with no refrigerant fluid, also
forecast in the 1950's and 1960's.

So we have high pressure tanks. Big -------- Deal. That is only a tiny
and impractical step.

jbuch

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Apr 23, 2005, 9:51:46 AM4/23/05
to
Robert Clark wrote:

Aren't you the guy that wanted to build a "Skyhook" tower based upon
pressurized structural tubes?

Wasn't the paper you based your proposal upon flawed and inappropriate,
as discussed briefly by the original author?

Your focus on PRESSURE is noted.
--
...............................


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Robert Clark

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Apr 23, 2005, 10:43:07 AM4/23/05
to

jbuch wrote:

> Robert Clark wrote:
>
>
> Aren't you the guy that wanted to build a "Skyhook" tower based upon
> pressurized structural tubes?
>
> Wasn't the paper you based your proposal upon flawed and
inappropriate,
> as discussed briefly by the original author?
>
> Your focus on PRESSURE is noted.
> --
> ...............................
>

The application I'm considering is for carrying very high pressure
fluids vertically to kilometer altitudes. That proposal was not
dependent on the Landis paper. Reference to that was only to get the
formula online for taper ratio to height for high altitude towers. This
is a well-known formula available in many papers. The Landis paper had
it in an online source.


Bob Clark

jbuch

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Apr 23, 2005, 11:49:12 AM4/23/05
to
Nevertheless, it appears as if you have a SOLUTION = PRESSURE, and you
are looking for PROBLEMS that it will solve.

The Skyhook and now the HYDROGEN ECONOMY.

It isn't unnatural, some great things have come from this seeming dogged
focus on a "solution". But, on balance, a lot of such efforts have been
merely mildly interesting efforts focused on a solution looking for a
problem.

Robert Clark wrote:

Uncle Al

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Apr 23, 2005, 12:42:09 PM4/23/05
to
Robert Clark wrote:
>
> Uncle Al wrote:
> > Robert Clark wrote:
> > ...
> > Hopeless idiot. The H*Y*D*R*O*G*E*N car is bullshit. The densest
> > storage of hydrogen, atoms/liter, is diesel - and you can do that in
> > an open bucket without paying for /_\PV.

> "Dr. Strange Al, or how I learned how to stop worrying and love


> pollution."
>
> Reading Al's posts on this topic you get the feeling he doesn't WANT
> cars to run on pure hydrogen even if it is feasible to do so.

"Ye canna' break the laws of physics." Yer screwed, Clarke - starting
with where you mine the hydrogen - as assuredly as the E*L*E*C*T*R*I*C
car was dead dead dead one business day after Federal subsidies
terminated.

The H*Y*D*R*O*G*E*N car is bullshit. Are you going to have a 10,000
psi storage tank the volume of a car's trunk? A 2000 lb tank of
metal matrix storage (e.g., HYSTOR) that is poisoned by trace CO or
SO2? 500 lbs of single wall carbon nanotubes for adsorption? Build
national distribution and storage networks?

Hey stooopid, how many gas stations are there in the US?

Get this through your thick insane head: By a huge margin (even on a
log-axis), the densest storage of hydrogen - atoms/liter - is diesel.
You can do that in an uncovered $1.50 bucket from K-Mart. Diesel
comes out of the ground for no more than $2.00/bbl amortized cost as
petroleum. Not cost per gallon, jackass, cost per barrel. That is
what Arabian crude production costs. They cap and forget any well
that is not a gusher.

Uncle Al

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Apr 23, 2005, 12:52:32 PM4/23/05
to
Robert Clark wrote:
[snip]

> We already have light-weight tanks that can hold 10,000
> psi.

A 400 liter 10,000 psi tank of hydrogen contains less here-to-there
than my VW Golf's modest gasoline tank. The hydrogen tank also
contains

(400 liters)(680 atmospheres)(101.235 J/l-atm) =

27.5 megajoules of /_\PV energy. That is the energy of detonation of
14.5 lbs of TNT after a minor rear-ender. KA-FUCKING-BOOM!
(Apologies tendered to readers for author's inability to display
sufficiently bold and large font in 7-bit Usenet.) Add ignition as
pleases you.

BTW, jackass, that is the energy you must INPUT to pressurize the
tank. It is unrecoverable upon discharge. How much gasoline must you
burn to run the compressor to fill your 10,000 psi hydrogen tank? Oh,
wait! You'll burn HYDROGEN! Idiot.

Uncle Al

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Apr 23, 2005, 12:57:48 PM4/23/05
to

Hey stooopid, viscous laminar flow varies as (radius)^4. Going from a
10 mm ID to a 0.5 mm ID gives you 1/160,000 the flow for the same
pressure drop. You don't have high pressure, jackass, you are
disharging the storage volume. If you have high pressure flow
maintained you get turbulence and you STILL don't get any flow. If
you try to push supersonic the bore chokes. You STILL don't get any
flow.

Hey stooopid, what length of 0.5 mm bore must you accumulate to store
400 liters of volume? Will the H*Y*D*R*O*G*E*N car pull a 16-wheel
trailer? Oh yeah, every bend screws your flow rate big time.

mme...@cars3.uchicago.edu

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Apr 23, 2005, 3:34:03 PM4/23/05
to
The belief that anything that can be done at some specific scale (in a
"cost is not an object" situation) can be "clearly" be scaled to
arbitrary large size, at arbitrarily small cost, is one of the
hallmarks of a deluded enthusiasm. And the belief that somebody just
wants to have more polution is a hallmark of utter stupidity. I think
that my sig is giving me a clear signal here. So long.

The Ghost In The Machine

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Apr 23, 2005, 4:00:03 PM4/23/05
to
In sci.physics, Uncle Al
<Uncl...@hate.spam.net>
wrote
on Sat, 23 Apr 2005 09:52:32 -0700
<426A7D50...@hate.spam.net>:

> Robert Clark wrote:
> [snip]
>
>> We already have light-weight tanks that can hold 10,000
>> psi.
>
> A 400 liter 10,000 psi tank of hydrogen contains less here-to-there
> than my VW Golf's modest gasoline tank.

45 MJ/liter gasoline. Assuming 30 mpg = 7.925 miles/liter
= 12.754 km/liter, that's 3.529 * MJ/km. Assuming a 15 gallon
= 56.87 liter gas tank that's a cruising range of 450 miles
or 725 km, though one might want to allow for error.
Total energy: 2.559 gigaJoules.

10000 psi = 69 megaPascal.
400 liter = 0.4 m^3.
n = PV/(RT) = 6.9*10^7 * 0.4 / (8.314472 * 300) = 1.107 * 10^4 moles.
Reaction: H2 + 1/2 O2 = H2O + 285.8 kJ/mole H2.
Total energy: 3.164 gigaJoules.

Of course, that Golf probably won't be able to hold a 400 liter
hydrogen gas tank. :-) I'm also curious as to the weight of the
tanks per megaJoule; I've not accounted for acceleration to
cruising speed, which for a 2 metric tonne car accelerating to
30 m/s = 67.1 km/hr is .9 megaJoule right there. Every extra
kg requires 450J in the budget -- and then one has to worry
about breaking.

But never mind that, hydrogen cars are the future! If only because
Bush & Co. say so -- assuming anyone believes them at this point.


> The hydrogen tank also
> contains
>
> (400 liters)(680 atmospheres)(101.235 J/l-atm) =
>
> 27.5 megajoules of /_\PV energy. That is the energy of detonation of
> 14.5 lbs of TNT after a minor rear-ender. KA-FUCKING-BOOM!
> (Apologies tendered to readers for author's inability to display
> sufficiently bold and large font in 7-bit Usenet.) Add ignition as
> pleases you.

14.5 lbs TNT = 30 MJ = about 16.7x the energy of a head-on collision
between two metric tonne vehicles both moving at 30 m/s (67.1 mph).

# # # ###### ####### ####### # #
# # # # # # # # # # ## ##
# # # # # # # # # # # # # #
### # # ###### # # # # # # #
# # ####### # # # # # # # #
# # # # # # # # # # # #
# # # # ###### ####### ####### # #

Fortunately for most of the rest of us, gasoline doesn't
explode all that readily and gas tanks are well protected.
(Except in '74 Pintos. I don't know regarding Golfs. :-) )

Hydrogen might be even safer, were it not for the pressure.
Presumably, that's the killer, here.

>
> BTW, jackass, that is the energy you must INPUT to pressurize the
> tank. It is unrecoverable upon discharge. How much gasoline must you
> burn to run the compressor to fill your 10,000 psi hydrogen tank? Oh,
> wait! You'll burn HYDROGEN! Idiot.
>

The tank pressurization energy should be partially recoverable though
I'm not sure exactly how, but prototype liquid nitrogen cars have
been suggested by a Webpage somewhere; I'd have to find it now.
Of course, they're far worse than hydrogen, mileage-wise.

I am not so naive to think we can recover all of it, of course, and
I doubt that significant recovery is even possible, as the regulator
(the bit that actually releases the gas) will probably freeze up.

<mode voice="habshi"> Of course we might be able to convert that
into air conditioning. </mode> :-)

--
#191, ewi...@earthlink.net
It's still legal to go .sigless.

Uncle Al

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Apr 23, 2005, 4:15:49 PM4/23/05
to

That is a nice set of numbers you have there! A 400 liter 10,000 psi
hydrogen tank will give the same driving range as a tank of gasoline
in a VW Golf, if it is weightless and threads to fill the entire
underside volume of the car. If it ruptures the /_\PV energy release
is 16X the energy of a 70 mph head-on collision between two luxury
cars... the same amount of energy being needed each time to fill it at
pressure.

The solution? Fuel cells! Why a child could have thought of it -
preferably one pre-arithmetic.

CWatters

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Apr 23, 2005, 5:10:50 PM4/23/05
to

"Robert Clark" <rgrego...@yahoo.com> wrote in message
news:1114259876.9...@g14g2000cwa.googlegroups.com...

How big are carbon fibres? I found this abstract that suggests "large
diameter fibres" are 15-60 microns!


Dan Bloomquist

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Apr 23, 2005, 5:15:42 PM4/23/05
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G. R. L. Cowan wrote:

> Dan Bloomquist wrote:
>>
>>Feasible and practical are not the same concept. Arnold Schwarzenegger
>>gets 50 miles of range with his new H2 Hummer. (And I'll bet he has to
>>keep his foot out of it for even that.) How much did that vehicle and
>>fuel cost? And the big question that never seems to get addressed,
>>'Where does the hydrogen come from?'
>
> Maybe I missed something, but I believe Arnold has still converted
> zero Hummers. GM converted one, and staged a mockery of a travesty
> of a sham where a hose was put in this hummer, connected to a dummy
> hydrogen pump, held by an actor playing the governor. No hydrogen
> was transferred.

I read it a few weeks ago. I'm not surprised if it was a sham.

> --- Graham Cowan, former hydrogen fan

Best, Dan.

Jonathan Barnes

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Apr 23, 2005, 7:47:42 PM4/23/05
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> >> We already have light-weight tanks that can hold 10,000
> >> psi.
> >
> > A 400 liter 10,000 psi tank of hydrogen contains less here-to-there
> > than my VW Golf's modest gasoline tank.

Doing a little thinking out loud,

the most efficient pressure tank is a sphere.

for 400 l capacity
0.4 = 4/3 x pi x r^3 gives a diameter of 915 mm

cross section of tank = 0.915 ^2 / 4 x pi = 0.657 m^2

pressure is 10,000 psi = 67 MPa

strength of steel = 430 MPa

area of tank wall = pi x 0.915 x t = 2.87 x t

If we had a safety factor of 2.5, wall stress is 172 MPa

172 x 2.87 x t = 0.657 x 67
wall of tank is t = 90 mm ( thin wall assumption " pushed " )

tank wall volume = pi x 0.915^2 x 0.09 = 0.270 m^3

density of steel = 7.81 tonnes / m^3

weight of tank = 2.1 tonnes

When your fuel tank weighs a couple of tons you need a big vehicle which
needs a lot of fuel..... :-)


--
Jonathan

Barnes's theorem; for every foolproof device
there is a fool greater than the proof.

To reply remove AT


Robert Clark

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Apr 23, 2005, 7:58:15 PM4/23/05
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You said feasible not cost effective. Anyways the benchmark set by the
U.S. government is 6.5% storage by weight and we're already close to
that. A company called Quantum claims 6% storage at 10,000 psi gas
pressure with carbon composite tanks. This is hardly the difficulty
level of creating controlled nuclear fusion or even going to the Moon.
You should read Uncle Al's post more carefully. Anything whose
*purpose* is reduce pollution incurs his wrath.

Bob Clark

G. R. L. Cowan

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Apr 23, 2005, 8:18:07 PM4/23/05
to
Jonathan Barnes wrote:
>
> > >> We already have light-weight tanks that can hold 10,000
> > >> psi.
> > >
> > > A 400 liter 10,000 psi tank of hydrogen contains less here-to-there
> > > than my VW Golf's modest gasoline tank.
>
> Doing a little thinking out loud,
>
> the most efficient pressure tank is a sphere.
>
> for 400 l capacity
> 0.4 = 4/3 x pi x r^3 gives a diameter of 915 mm
>
> cross section of tank = 0.915 ^2 / 4 x pi = 0.657 m^2
>
> pressure is 10,000 psi = 67 MPa
>
> strength of steel = 430 MPa
>
> area of tank wall = pi x 0.915 x t = 2.87 x t
>
> If we had a safety factor of 2.5, wall stress is 172 MPa
>
> 172 x 2.87 x t = 0.657 x 67
> wall of tank is t = 90 mm ( thin wall assumption " pushed " )
>
> tank wall volume = pi x 0.915^2 x 0.09 = 0.270 m^3
>
> density of steel = 7.81 tonnes / m^3
>
> weight of tank = 2.1 tonnes
>
> When your fuel tank weighs a couple of tons you need a big vehicle which
> needs a lot of fuel..... :-)

Two tonnes of tank wall, 13 kg of payload.

Instead of weighing as much as a regular car,
an automotive hydrogen tank can cost as much as one:
the carbon filament-wound tanks in the GM Hy-Wire and Sequel
vehicles, if they exist. At 5,000 psi, 2 kg H2 is contained
in only 75 kg of tank.

Or it can be a Dewar and not have the PV bomb feature,
and be much more compact, and so score a much lower mass ratio --
http://www.visionengineer.com/env/h2_liquid.shtml ,
http://www.magnasteyr.com/automobilentwicklung/1342_1354_ENG_HTML.asp --
on the order of 15, but I don't know how expensive.
Not as bad as a carbon fibre tank, I guess.


--- Graham Cowan, former hydrogen fan

G. R. L. Cowan

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Apr 23, 2005, 8:21:23 PM4/23/05
to

IIRC, hybrids don't.

Jonathan Barnes

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Apr 23, 2005, 8:11:23 PM4/23/05
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"Uncle Al" <Uncl...@hate.spam.net> wrote in message

> Hey stooopid, what length of 0.5 mm bore must you accumulate to store
> 400 liters of volume? Will the H*Y*D*R*O*G*E*N car pull a 16-wheel
> trailer? Oh yeah, every bend screws your flow rate big time.
>

Hay Uncle Al

I'm happy to call a bend radius of twice the pipe diameter as low
restriction, so your 0.5 mm bore pipe should be O.K. with 1 mm radius
bends....

Uncle Al

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Apr 23, 2005, 8:28:16 PM4/23/05
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"G. R. L. Cowan" wrote:
>

1) "Two tonnes of tank wall, 13 kg of payload." All you need is an
engineering staff, some workstations, and optimization algorithms.
Reality cannot stand before political convenience.

2) What makes you think organics would hold 10,000 psi hydrogen
against diffusion? Ever see a fiberglas Corvette 24 hrs after a minor
fender ding? The whole body crazes. Pumping up and discharging an
organic wall tank to 10,000 psi 50 times/year for five years is not a
clever idea.

3) Housewife + liquid hydrogen = TV sitcom.

4) A hydrogen-burning engine would be a major NOx polluter. A fuel
cell car would be an expensive joke.

5) The densest hydrogen storage modality - atoms/liter - is diesel
fuel in a bucket. We already have both, plus distribution networks in
place.

Uncle Al

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Apr 23, 2005, 8:52:12 PM4/23/05
to
Jonathan Barnes wrote:
>
> "Uncle Al" <Uncl...@hate.spam.net> wrote in message
>
> > Hey stooopid, what length of 0.5 mm bore must you accumulate to store
> > 400 liters of volume? Will the H*Y*D*R*O*G*E*N car pull a 16-wheel
> > trailer? Oh yeah, every bend screws your flow rate big time.
> >
> Hay Uncle Al
>
> I'm happy to call a bend radius of twice the pipe diameter as low
> restriction, so your 0.5 mm bore pipe should be O.K. with 1 mm radius
> bends....

It's not bore crimping that kills gas conductance, it's the bend
itself even if it is perfect. Momentum! Every bend is death, every
stopcock is death, every through-fitting and jog is a slap in the
face.

Uncle Al's vac line was really big bore tubing with big bore big
cryogenic traps (hooked up "backwards" so they worked without
clogging) with the largest greaseless screwdown stopock made leading
to a direct drive forepump. Down the hall was a very elegant
fairyland creation of mostly 7 mm Pyrex tubing and greaseless
connections swirled into a bouffant vac-do, ending in a huge forepump
backing a huge silicone vapor pump. The thing had huge bucks in it.

Big bad chemist, "Hey Al, bet you $20 my line pumps down faster than
your line."
Uncle Al, "Make that $100."

Stopwatch; pressure gauge at the far end of the line. My line could
not be expected to pull better than 5 microns. Open the line to air,
close. Flip the pump switch. The gauge dropped then oozed to about 6
microns over a few minutes and hung. Was Uncle Al out $100?

Stopwatch; pressure gauge at the far end of the line. His line could
be expected to pull better than 10^(-3) microns... eventually. Open
the line to air, close. Flip the forepump switch, then engage the
vapor pump when the pressure dropped. His line got to 6 microns at
the far end in more than double the time mine did - as every
greaseless connection in-between was outgassing just a teensy to put
icing on the cake.

It matters not how hard you suck at the near end. The far end is
kinetics not thermodynamics. I don't know what his vac line actually
did in his lab. Whatever it did it took a long time to do it if
non-condensable gas was being evolved. My vac line occasionally
explosively decompressed garden snails in the morning. POOF!
Partially frozen puffed snail. I hate snails.

rgrego...@yahoo.com

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Apr 23, 2005, 9:31:18 PM4/23/05
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The Ghost In The Machine wrote:
> ...

> The tank pressurization energy should be partially recoverable though
> I'm not sure exactly how, but prototype liquid nitrogen cars have
> been suggested by a Webpage somewhere; I'd have to find it now.
> Of course, they're far worse than hydrogen, mileage-wise.
>
> I am not so naive to think we can recover all of it, of course, and
> I doubt that significant recovery is even possible, as the regulator
> (the bit that actually releases the gas) will probably freeze up.
>
> <mode voice="habshi"> Of course we might be able to convert that
> into air conditioning. </mode> :-)
>
> --
> #191, ewi...@earthlink.net
> It's still legal to go .sigless.

You could use the high pressure gas to run a turbine and then on top
of that burn the hydrogen in an internal combustion engine.
To get an idea of the power that might be generated by the turbine, we
can calculate the speed achieved when the gas is released to ambient
pressure. For an incompressible gas approximation, the Bernoulli
formula implies v = (Pressure/density)^.5. For the 2200 bar pressure,
200 K temperature, 62.4 kg/m^3 density I originally suggested, this
would result in v = (2.2*10^8Pa/62.4kg/m^3)^.5 = 1877.7 m/s.
At 300K and 2200 bar, the "Hydrogen Properties Package" page gives the
density as 48.2 kg/m^3. Then the speed would be 2136.4 m/s.
Perhaps someone familiar with turbine engineering could calculate the
power that could be generated.

Bob Clark

rgrego...@yahoo.com

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Apr 23, 2005, 9:43:32 PM4/23/05
to

That's why I suggested the ultrafast laser approach:

Introduction to Micromachining Handbook.
http://www.cmxr.com/Industrial/Handbook/Introduction.htm

A very informative including some nice animations illustrating the
process.
Another posibility might be to use high pressure waterjets to cut
channels in the fibers. These can cut through steel with a combination
of pressure and velocity. The smallest diameter jets I've seen are
about .01" inches wide or 250 microns. It may be possible to reduce the
diameter of these jets to less than 10 micron diameter.
Keep in mind also that I don't know that any of these high strength
fibers maintain their longitudinal strength cross-wise or if they have
been tested yet.


Bob Clark

rgrego...@yahoo.com

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Apr 23, 2005, 10:49:00 PM4/23/05
to
Jonathan Barnes wrote:
> > >> We already have light-weight tanks that can hold 10,000
> > >> psi.
> > >
> > > A 400 liter 10,000 psi tank of hydrogen contains less
here-to-there
> > > than my VW Golf's modest gasoline tank.
>
> Doing a little thinking out loud,
>
> the most efficient pressure tank is a sphere.
>
> for 400 l capacity
> 0.4 = 4/3 x pi x r^3 gives a diameter of 915 mm
>
> cross section of tank = 0.915 ^2 / 4 x pi = 0.657 m^2
>
> pressure is 10,000 psi = 67 MPa
>
> strength of steel = 430 MPa
>
> area of tank wall = pi x 0.915 x t = 2.87 x t
>
> If we had a safety factor of 2.5, wall stress is 172 MPa
>
> 172 x 2.87 x t = 0.657 x 67
> wall of tank is t = 90 mm ( thin wall assumption " pushed " )
>
> tank wall volume = pi x 0.915^2 x 0.09 = 0.270 m^3
>
> density of steel = 7.81 tonnes / m^3
>
> weight of tank = 2.1 tonnes
>
> When your fuel tank weighs a couple of tons you need a big vehicle
which
> needs a lot of fuel..... :-)
>
>
> ...

I'm proposing using materials whose tensile strength is more than 10
times 430 Mpa. If the Scifer steel does have 5.5 Gpa tensile strength
cross-wise then the thickness will only have to be 430/5500 as big and
therefore the mass will also decrease by this factor to 430/5500 *
2100kg = 164kg.
Carbon fibers have comparable strength but only 1/5th the weight so
the mass would be 164kg/5 = 33kg.

Bob Clark

rgrego...@yahoo.com

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Apr 23, 2005, 11:02:05 PM4/23/05
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Uncle Al wrote:
> ...

> Get this through your thick insane head: By a huge margin (even on a
> log-axis), the densest storage of hydrogen - atoms/liter - is diesel.

> You can do that in an uncovered $1.50 bucket from K-Mart. Diesel
> comes out of the ground for no more than $2.00/bbl amortized cost as
> petroleum. Not cost per gallon, jackass, cost per barrel. That is
> what Arabian crude production costs. They cap and forget any well
> that is not a gusher.
>

> ...

Unless you're going to use this diesel fuel in a reformer to convert
it into hydrogen, this is irrelevant to the issue at hand. You remember
reformers, right Al? Their PURPOSE is to reduce POLLUTION.
But since they use diesel fuel should like them right?


Bob Clark

rgrego...@yahoo.com

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Apr 24, 2005, 12:04:00 AM4/24/05
to

Uncle Al wrote:
> Robert Clark wrote:
> [snip]
>
> > We already have light-weight tanks that can hold 10,000
> > psi.
>
> A 400 liter 10,000 psi tank of hydrogen contains less here-to-there
> than my VW Golf's modest gasoline tank. The hydrogen tank also
> contains
>
> (400 liters)(680 atmospheres)(101.235 J/l-atm) =
>
> 27.5 megajoules of /_\PV energy. That is the energy of detonation of
> 14.5 lbs of TNT after a minor rear-ender. KA-FUCKING-BOOM!
> (Apologies tendered to readers for author's inability to display
> ...

I thought you said you couldn't get that energy added by the pressure
out again?
For a controlled use of this pressure, use a turbine.

Bob Clark

rgrego...@yahoo.com

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Apr 24, 2005, 12:10:41 AM4/24/05
to
G. R. L. Cowan wrote:
> Robert Clark wrote:
> >
> > Uncle Al wrote:
> > > Robert Clark wrote:
> > > ...
> > > Hopeless idiot. The H*Y*D*R*O*G*E*N car is bullshit. The
densest
> > > storage of hydrogen, atoms/liter, is diesel - and you can do that
in

> > > an open bucket without paying for /_\PV.
> > >
> > > --
> > > Uncle Al
> >
> > "Dr. Strange Al, or how I learned how to stop worrying and love
> > pollution."
> >
> > Reading Al's posts on this topic you get the feeling he doesn't
WANT
> > cars to run on pure hydrogen even if it is feasible to do so.
>
> http://www.hydrogen.org/h2cars/overview/main01.html
>
> That's a lot of prototypes, and a lot of years, for zero sales.
>
>

These vehicles are still in the prototype stage, but look at the later
years here for more successful renditions:

H2Cars.
http://www.hydrogen.org/h2cars/overview/

Bob Clark

George Dishman

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Apr 24, 2005, 4:04:00 AM4/24/05
to

<rgrego...@yahoo.com> wrote in message
news:1114311725.7...@l41g2000cwc.googlegroups.com...

If your concern is to reduce CO2 production,
then consider a simpler alternative. If the
fuel recycles atmospheric carbon then there
is no net production:

http://www.absoluteastronomy.com/encyclopedia/B/Bi/Biodiesel.htm

or

http://www.absoluteastronomy.com/encyclopedia/B/Bi/Bioalcohol.htm

Check out what Brazil is doing.

George


Jonathan Barnes

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Apr 24, 2005, 6:38:40 AM4/24/05
to

<rgrego...@yahoo.com> wrote in message
news:1114310940.3...@l41g2000cwc.googlegroups.com...

Such as ??? Unidirectional louse carbon fibre is not a material you can
make a tank out of.
At best 35% of your material is the matrix, and you need strength in a plane
so you need twice as much as for a unidirectional material.

What is the density of the composite.. should be a lot less than steel thus
saving weight.

>If the Scifer steel does have 5.5 Gpa tensile strength

I think these " super " materials can only be fibers a few atoms thick..

Carbon fibres may be forty times the strength of steel on a weight for
weight basis, but for a carbon fibre bi directional composite it's a lot
less.
about 12 times might be realistic.

if we say the tank will be a metre in diameter and weigh 170 kg it's still a
problem to fit in a conventional car.

Jonathan Barnes

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Apr 24, 2005, 6:38:39 AM4/24/05
to

"Uncle Al" <Uncl...@hate.spam.net> wrote

> "G. R. L. Cowan" wrote:
> > Jonathan Barnes wrote:
> > >
> > > > >> We already have light-weight tanks that can hold 10,000
> > > > >> psi.
> > > > >
> > > > > A 400 liter 10,000 psi tank of hydrogen contains less
here-to-there
> > > > > than my VW Golf's modest gasoline tank.
> > >
> > > the most efficient pressure tank is a sphere.
> > >
> > > for 400 l capacity
> > > 0.4 = 4/3 x pi x r^3 gives a diameter of 915 mm
> > >
> > > weight of steel tank ( approx ) = 2.1 tonnes

> > >
> > Two tonnes of tank wall, 13 kg of payload.
> >
> > Instead of weighing as much as a regular car,
> > an automotive hydrogen tank can cost as much as one:
> > the carbon filament-wound tanks in the GM Hy-Wire and Sequel
> > vehicles, if they exist. At 5,000 psi, 2 kg H2 is contained
> > in only 75 kg of tank.
> >
> 2) What makes you think organics would hold 10,000 psi hydrogen
> against diffusion?

A coating of something needed ???

> Pumping up and discharging an
> organic wall tank to 10,000 psi 50 times/year for five years is not a
> clever idea.

I think you will have trouble with the matrix material at the high
pressures, but wound tanks do prefom well, but they are expensive, and there
is little on cost to be saved with volume production...

> 3) Housewife + liquid hydrogen = TV sitcom.

More a disaster movie I would think :-)


>
> 4) A hydrogen-burning engine would be a major NOx polluter. A fuel
> cell car would be an expensive joke

Fuel cell could improve drematicaly, but the hydrogen storage problem
remains.... methane powered cells look interesting... but they are to
complicated and thus are very expensive.

> 5) The densest hydrogen storage modality - atoms/liter - is diesel
> fuel in a bucket.

Can you supply the energy value ( Mj / kg ) for diesel and hydrogen ?

Robert Clark

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Apr 24, 2005, 10:25:32 AM4/24/05
to
Jonathan Barnes wrote:
> <rgrego...@yahoo.com> wrote in message

After a web search, these Scifer steel wires are about 10 microns
thick. The measured longitudinal tensile strength of these wires is 5.5
Gpa. Carbon fibers in use have longitudinal tensile strength about 7
Gpa.
Whether they can maintain this strength cross-wise is what I'm
suggesting should be investigated.
Quantum Technologies has in production carbon composite hydrogen tanks
that can hold 8 kg of hydrogen at 10,000 psi to fit in a standard size
car. This is enough to drive a prototype vehicle 300 miles, 480 km. The
carbon composite design makes these tanks much lighter than a
comparable steel tank:

GM launches latest stage of its hydrogen 'moonshot'.
Sequel concept is a five-seat SUV with a 300-mile range.
http://www.detnews.com/2005/autoshow/0501/09/-54837.htm

Bob Clark

G. R. L. Cowan

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Apr 24, 2005, 10:44:09 AM4/24/05