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ERRORIST

Member

From: OXFORD ALABAMA

Registered: 2004-01-28

Posts: 1,182

Re: Capillary action in a carbon nanotube???

How high would H2O rise up the tube from sea level?
How high up the tube would liquid H2 rise up the tube once compressed to a liquid?

A typical nanotube is 3 to 4 H2 molecules across.

GraemeSkinner

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From: Eden Hall, Cumbria

Registered: 2004-02-20

Posts: 563

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Re: Capillary action in a carbon nanotube???

*Austin Stanley already answered this question in the Gravity wheel thread did he not?

Capillary action is not infinate, there is a limit as to how high it will alow a liquid to rise.  You can caluclate that distance via the following equasion:

H = 2T/drg

H is the distance the liquid will rise
T is the surface tension bettwen the liquid and the tube
d is the liquid's density
r is the radius of the tube
g is acceleration due to gravity

I am unsure what the surface tension would be bettwen carbon nano-tubes and any given liquid, but if you knew that you could calculate the height.  However, this all may be misleading because at such small distance (nano-meters) the action of surface tension may break down.

So not far at all then.

Graeme

---

There was a young lady named Bright.
Whose speed was far faster than light;
She set out one day
in a relative way
And returned on the previous night.
--Arthur Buller--

ERRORIST

Member

From: OXFORD ALABAMA

Registered: 2004-01-28

Posts: 1,182

Re: Capillary action in a carbon nanotube???

However, this all may be misleading because at such small distance (nano-meters) the action of surface tension may break down.

So, I guess there is no real way to find out unless you do an experiment.

John Creighton

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From: Nova Scotia, Canada

Registered: 2001-09-04

Posts: 2,401

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Re: Capillary action in a carbon nanotube???

However, this all may be misleading because at such small distance (nano-meters) the action of surface tension may break down.

So, I guess there is no real way to find out unless you do an experiment.

Will water even fit inside a nanotube?

---

Dig into the [url=http://child-civilization.blogspot.com/2006/12/political-grab-bag.html]political grab bag[/url] at [url=http://child-civilization.blogspot.com/]Child Civilization[/url]

GCNRevenger

Member

From: Earth

Registered: 2003-10-14

Posts: 6,056

Re: Capillary action in a carbon nanotube???

Actually no, you can pretty well estimate what would happen.

Bascially, since the tube is so EXTREMELY small, there isn't enough room for the molecules to assemble themselves, so the capillary action won't work very well at all.

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[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

ERRORIST

Member

From: OXFORD ALABAMA

Registered: 2004-01-28

Posts: 1,182

Re: Capillary action in a carbon nanotube???

So the molecules would always stay as a gas even if you pump it up?

GCNRevenger

Member

From: Earth

Registered: 2003-10-14

Posts: 6,056

Re: Capillary action in a carbon nanotube???

Down on the scales you are talking about Errorist, there is really not that much distinction between "gas" and "liquid"

It wouldn't rise very high unless you used extreme pressure differentials.

---

[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

ERRORIST

Member

From: OXFORD ALABAMA

Registered: 2004-01-28

Posts: 1,182

Re: Capillary action in a carbon nanotube???

Even if you did that would it combine to form a liquid or just always remain a gas no matter what the pressure difference is?

GCNRevenger

Member

From: Earth

Registered: 2003-10-14

Posts: 6,056

Re: Capillary action in a carbon nanotube???

Errorist, you aren't understanding. The concept of "liquid" doesn't so much apply on extremely small scales (single number angstroms).

You better not be going back to the 20-page treatise on why using CNTs for fuel transport to orbit is a dumb idea, are you?

---

[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

Trebuchet

Banned

From: Florida

Registered: 2004-04-26

Posts: 419

Re: Capillary action in a carbon nanotube???

Two serious methods of transferring fuel occur to me: One is to design the engine/pump assembly/etc to be seperate from the actual fuel/oxidizer, which should be designed as a modular unit that can be plugged into the engine assembly with a minimum of fuss, but this is probably too complicated; the other, probably more doable method, borrows from the method the Army uses to refuel tanks in a hurry.

The US Army has this entertaining method of fueling a tank in a hurry whereby they use a large flexible bladder-like device full of fuel, attach a hose to the fuel tanks, and then run over the bladder, forcing fuel into the tanks without any complicated equipment (other than the tank itself, of course). I was thinking that designing a fuel transfer vehicle so that it has the bladder inside a fuel tank, and another bladder, empty at takeoff, which can be filled in orbit with some inert gas like helium or nitrogen. The expanding second bladder would crush the fuel or oxidizer bladder and force fuel through the refueling attachment into the other craft. This would seem to solve a lot of problems with the 'no gravity' situation of transferring fuel in orbit. The same system could be used to transfer bulk water, too.

GCNRevenger

Member

From: Earth

Registered: 2003-10-14

Posts: 6,056

Re: Capillary action in a carbon nanotube???

No see, Errorist continued to push his idea of making a carbon nanotube pipeline to orbit, that is, a pipe with Hydrogen compressed into the Earthly end and it be collected at the top in geostationary orbit.

This of course won't work, because gasses are not contiguous blobs of matter but are actually collections of unbound molecules bouncing around with mostly empty space surrounding them. Since gravity on Earth is so strong, none of the hydrogen molecules reach escape velocity at reasonable temperatures - which determines the speed of the molecules, not pressure - so none of the gas would make it to the top. Gravity would just compress it at the bottom.

The pressures needed to force liquified hydrogen into the pipeline were so high, that hydrogen would slip between the atoms of anything except diamond and the pump would brittle and shatter. Diamond and CNT material are also chemically vulnerable to attack by hydrogen, which would cause them to break down too.

---

[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

RobS

Banned

From: South Bend, IN

Registered: 2002-01-15

Posts: 1,701

Website

Re: Capillary action in a carbon nanotube???

I don't think anyone has yet designed a bladder material that remains flexible at cryogenic temperatures.

       -- RobS

ERRORIST

Member

From: OXFORD ALABAMA

Registered: 2004-01-28

Posts: 1,182

Re: Capillary action in a carbon nanotube???

I still think the hygrogen would flow to the top as it does now with out the pipe into space.
However, in this case I think since just a few molecules at a time can make it through the tube since its diameter is so small. It would be a more effiecent fuel injector for any type of engine including ion engines. It would atomize the fuel better .

GCNRevenger

Member

From: Earth

Registered: 2003-10-14

Posts: 6,056

Re: Capillary action in a carbon nanotube???

You might get a few molecules at the top, but the yeild would be so low and the pump & pipe break down so easily, that it would never work.

The fuel is already broken down, its a gas!

---

[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

John Creighton

Member

From: Nova Scotia, Canada

Registered: 2001-09-04

Posts: 2,401

Website

Re: Capillary action in a carbon nanotube???

Why not just put multiple pumps along the tube?  ??? It would make alot more sence. Oh yeah and use a tube with a little bigger diamater then carbon nano tubes.

---

Dig into the [url=http://child-civilization.blogspot.com/2006/12/political-grab-bag.html]political grab bag[/url] at [url=http://child-civilization.blogspot.com/]Child Civilization[/url]

ERRORIST

Member

From: OXFORD ALABAMA

Registered: 2004-01-28

Posts: 1,182

Re: Capillary action in a carbon nanotube???

Great idea they have multiple stage boiler feed pumps in power houses.

ERRORIST

Member

From: OXFORD ALABAMA

Registered: 2004-01-28

Posts: 1,182

Re: Capillary action in a carbon nanotube???

Great idea they have multiple stage boiler feed pumps in power houses. Hey,they can even be solar powered.

Trebuchet

Banned

From: Florida

Registered: 2004-04-26

Posts: 419

Re: Capillary action in a carbon nanotube???

I don't think anyone has yet designed a bladder material that remains flexible at cryogenic temperatures.

      -- RobS

Then use either use storable non-cyrogenic fuels or try something else - long coiled tanks that an aerogel ball can be pushed through like a piston by compressed gas, a rigid umbrella-like device that can open up inside the tank and pull down to force the fuel/oxidizer out, building a tank that has an insulative blanketlike thing around the gas bladder so IT can expand (regardless of whether or not the cyrogenic liquid can be stored in a flexible bag, the gas is storeable)...

GCNRevenger

Member

From: Earth

Registered: 2003-10-14

Posts: 6,056

Re: Capillary action in a carbon nanotube???

The gasses are so thin even above ~15,000ft that it would be useless. You would need so many pumps, probobly THOUSANDS of pumps, that it would never work. No practical space elevator would be strong enough to support them all, much less their power sources and wiring (which would suffer from severe electical transmission losses).

Plus the carbon nanotube "pipe" will be attacked by the Hydrogen and break down anyway.

---

[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

ERRORIST

Member

From: OXFORD ALABAMA

Registered: 2004-01-28

Posts: 1,182

Re: Capillary action in a carbon nanotube???

So use Helium. A pumping station every 1 mile up would work. That does not equate to thousands of pumps to get Helium in orbit at worst 250 pumps could do it.At best 5 pumps could do it.

GCNRevenger

Member

From: Earth

Registered: 2003-10-14

Posts: 6,056

Re: Capillary action in a carbon nanotube???

Errorist, I think you have a SERIOUS problem with realizing the scales of your crazy ideas. This pipe has to be about twenty four thousand miles long. Your arbitrary "250 pumps" is just pulled out of thin air.

Helium doesn't reach as high as Hydrogen due to lower molecular velocity, plus its worthless for combustion rocket fuel, and much harder to store because of its extremely low liquification temperature.

---

[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

ERRORIST

Member

From: OXFORD ALABAMA

Registered: 2004-01-28

Posts: 1,182

Re: Capillary action in a carbon nanotube???

Its good for ion drive and you can dump it out over to tanker or storage tank at the 250 mile elevation.

Euler

Member

From: Corvallis, OR

Registered: 2003-02-06

Posts: 922

Re: Capillary action in a carbon nanotube???

It would be much easier just to fill up a tank and use the elevator's normal ascenders to lift the fuel.

GCNRevenger

Member

From: Earth

Registered: 2003-10-14

Posts: 6,056

Re: Capillary action in a carbon nanotube???

No, and no:

-Helium has very very high ionization energy per mass, making an ion engine fueled by it very inefficent, requiring a much bigger power source

-The space elevator, at any point below geostationary orbit, is NOT moving at orbital velocity. Hence, no ships can dock with elevator at altitudes lower then geostationary since the elevator would be traveling hundreds or thousands of miles an hour relative to a stable orbital velocity.

---

[i]"The power of accurate observation is often called cynicism by those that do not have it." - George Bernard Shaw[/i]

[i]The glass is at 50% of capacity[/i]

ERRORIST

Member

From: OXFORD ALABAMA

Registered: 2004-01-28

Posts: 1,182

Re: Capillary action in a carbon nanotube???

We went over that one pump alone could not hold up to the task but a few pumps divided over the total distance can. Xenon could be pumped also. A series of multiple pumps could work. One pump pumps it to one elevation to the suction of another pump and so on. Remember the inside diameter of the tube is only 1/4 inch diameter.