Upside down "U" shaped manometer carbon nano tube

ERRORIST · 2004-11-19 11:01:01

How about if it was shaped like a Manometer U shaped but upside down where both open ends are hanging down near the surface? You could put an air ejector on one end and the hydrogen would flow into the other end. Near the top of the U you can tap into the line and get the H2.

John Creighton · 2004-11-19 11:27:31

This is called a siphon. People who make wine use it to transfer liquid from one carboy to another. Some people use to use it to steel gas but I believe new cars have protection for that now. I head you can get pretty high huffing gas. It can also be very dangerous if you swallow some. Anyway for a siphon there is a limit to how high the U can be. It depends on the density of the fluid and the amount of gravity. The siphon works because the falling fluid on the other side greats a vacuum. This is the exact same principle as a normal pump. If you extract fluid from the top of the siphon there is no down force to great the vacuum. If you create the vacuum with the pump the down part of the U is useless. If you put another fluid down the other side you created a gravity pump similar to a carburetor. This will weigh much more then an electric pump and the only possible reason I could see to use it is if you wanted a two weigh flow of fluid. Unfortunately I don’t know if such a device could be constructed anyway. A carburetor in a car mixes two fluids. In our case we want one fluid to go up and the other to go down.

GCNRevenger · 2004-11-19 11:31:47

No Errorist, this would not work either. The strong gravity of the Earth will just pull your Hydrogen back down before it ever reaches the top of the bend at geostationary orbit, just like your one-tube pipeline.

Pull all you want with a vacuum pump on the vacuum end, it won't do any good. In fact, you have the ultimate vacuum pump already made for you: space. The same reason space doesn't suck all our atmosphere away is the same reason that you can't suck Hydrogen up into space either: gravity.

You can't use normal plumbing math on this scale. You just cannot. The plumbing math is wrong, its just not wrong by very much over small distances and velocities.

ERRORIST · 2004-11-19 12:37:09

So as you pull the atmosphere out of one side the atmosphere that was displaced should rush up the other side in equal volume. Correct?

GCNRevenger · 2004-11-19 12:40:04

Through a 24,000 mile tall U-shaped pipe? Nope, not against Earth's gravity.

ERRORIST · 2004-11-19 13:07:09

Yep, right against Earths gravity: Here is how.

Step

1.0 ) Turn on vaccum pump.

2.0 ) Once the pump has removed all it can close suction valve on other open end and to vacuum pump suction valve.

3.0) Turn off vacuum pump.

4.0) Open suction valve above vacuum pump suction valve to allow atmosphere to rush back into pipe.

5.0) Close suction valve to vacuum pump once the atmosphere has rushed back in.

6.0) Open suction valve to vaccum pump and turn vacuum pump back on.

7.0) Open vacuum valve on other open end of upside down "U" tube again.

8.0) Repeat steps 1.0 through 7.0. over and over untill atmosphere reaches top of upside down "U" tube.

John Creighton · 2004-11-19 13:13:21

Do you mean use multiple pumps? We agreed you can do this but were concerned that it might weigh too much to be practice to build. Clearly the more it weighs the more it will cost to build and the more danger it will pose to earth if it falls down. There is still no reason for the u unless you want to return fluid to earth and I don't know if a siphon will work with gasses anyway. There will atleast be some mixing.

ERRORIST · 2004-11-19 13:26:17

The siphon will work once you get the system primed. Once it is primed then you can introduce the other gasses. Once the atmospehre is all purged from the system then there should be little mixing.

John Creighton · 2004-11-19 14:11:55

At the bottom the down gas is sucked out the down side of the first U and the up gas is pushed inside the upside of the first U.. You then open a valve connecting the down side of the first U to the down side of the second U. This removes over half the gas from the down side of the second U. You then open the valve connecting the upside to the downside of the second U. This Sucks out some of the remaining upgas from the upside of the second U. You then close that valve and then open the valve connecting the upside of the first U to the Up side of the second U and less then half the gas will make it to the upside of the second U. At each stage there will be mixing of the up gas and the down gas. In the end there may be to much mixing for the system to be worth while. The reason it works better for liquides is liquids stay roughly the same volume. But I don't even think there is a way to do it with liquids. Although you could send air bubbles up through a liquid.

ERRORIST · 2004-11-19 14:23:17

I think a liquid may be to heavy for the tube. I think any gas would work and later can be turned back into a liquid once in space.

John Creighton · 2004-11-19 14:48:36

I think a liquid may be to heavy for the tube. I think any gas would work and later can be turned back into a liquid once in space.

Use normal pumps powere transmitted by an RF waveguide. Forget about the upside down U. Or just winch a tank up a cable.

ERRORIST · 2004-11-19 14:51:21

John,
How would the math look for both ideas? Also, Explain the Rf wave guide to me how does it work?

John Creighton · 2004-11-19 14:57:27

http://www.freestudy.co.uk/fluid%20mech … .pdf]FLUID FLOW THEORY

Your probably interested in Newtonian Flow or LAMINAR flow. I believe the energy per mass lost in a fluid as it flows is called head loss. You are interested in the energy per mass minus the energy due to gravity. I don't know lets call it modified head loss. For a flow through pipes the head loss per length depends on the viscosity of the fluid the flow rate though the pipes and how wide the pipes are.

John Creighton · 2004-11-19 15:05:33

As for a tank climbing a thread it would depend on how fast the climber can climb. What would be reasonable would it go the speed of a horse, a car a train or a plane. One tank could be passed between climbers. This would allow a more continuous mass flow. However the thread can only support a limited weight.

John Creighton · 2004-11-19 15:23:16

One equation that might be useful is work is at least P DV or equivalently power is equal to P DV/dt.
So the greater the volume of the fluid you move the more energy it takes. However the lighter the fluid the less force it takes to move it up the pipe. The end result being that for a given efficiency the energy it takes to move the fluid up the pipe is the same per mass regardless of its density. I wonder if instead of having the pipe full from top to bottom if you could only have a section of it full at a time. That is only fill the section between two pumps at any one time. Well not exactly but if the density of the fluid was greater in once section then the others. This would kind of be like food going down the esophagus. If the pipe was made out of nano tubes it could support itself. At low flow rates a pipe should be just as efficient as a climber. At higher flow rates the pipe might move more fluid but might be less efficient then the climber to viscous or turbulent effects.

Another thing to think of is there are non mechanical ways to climb a thread. If the thread could support a wave guide then electromagnetic methods could be used to climb the thread kind of like a high speed train or elevator.

ERRORIST · 2004-11-19 15:26:53

Frictional loss will create head loss. But, that is what the pump will do. It will overcome that loss near the end and boost the pressure up again. Energy would be conserved inside the tube so any pressure difference created on one end will have an effect on the other end for either concept the upside down U tube or just the straight one.

John Creighton · 2004-11-19 15:31:23

Energy would be conserved inside the tube

Energy is conserved but entropy always increases. The friction causes the ordered flow to be turned into random thermal motion (A.K.A heat.) the heat can stay in the fluid or be transmitted though the pipe. You cannot reclaim all of this thermal energy and the equipment needed to reclaim some of the thermal energy will add more mass to your system. It is actually not practical to try to reclaim any of this thermal energy.

ERRORIST · 2004-11-19 15:36:18

Just let it conduct and radiate out of the tube wall. It should not prevent the fluid from rising as long as there are enough pumps.

John Creighton · 2004-11-19 17:55:07

Just let it conduct and radiate out of the tube wall. It should not prevent the fluid from rising as long as there are enough pumps.

That is true but the more pums needed the more it is going to weigh. It will work and it may be built in the future. It is all a question of economics and safety.

ERRORIST · 2004-11-19 18:15:53

What would be the most sensible distance between pumps? Consider todays materials.

John Creighton · 2004-11-20 09:42:15

What would be the most sensible distance between pumps? Consider todays materials.

http://physicsx.pr.erau.edu/Courses/Cou … f]Varation of pressure with altitude.

P=P_oe^(-h/a) where a=P_o/(g*rho_o)=8.55 Km for air.

Thus of 8.55 Km the pressure drops by 1/e=1/2.71828182845905=0.36787944117144
In other words after 8.55 Km the air pressure drops to 37% of the original. Or way can say it drops by 63%.

Now this is without any flow. So if the air isn't moving at all in your pipe and your pumps are spaced 8.55 km apart then each pump needs to supply 0.63 atmospheres of pressure. If however you space the pumps half 8.55 km then each pump needs to supply 1-exp(-1/2)=0.39346934028737 Atmospheres. Thus if you put the pumps right beside each other each pump needs to supply less pressure then if you space each one half weigh. The reason is that each pump has less air pushing on it. If you space each pump half way the flow rate will be greater because each pump will be moving a greater density of air. Moving a greater density of air will require a greater energy. Now if the air is moving the pumps must supply a greater pressure to overcome friction. As far as making the wave guide nanotubes are conductive so it might be possible to make a wave guide out of nano tubes. Also note that as the altitude gets higher and gravity gets weeker the pumps can be spaced further apart. Also note that as the altitude gets higher and gravity gets weaker the pumps can be spaced further apart.

Also see:
http://www.cgd.ucar.edu/cms/wcollins/AT … tm]Formula Sheet, First Midterm

This page has a formula that takes into account temperature variation. Since it gets colder at higher altitude the pump spacing may first decrease before it increases. Notice the connection between the universal gas constant and density.

John Creighton · 2004-11-20 09:48:50

I will point out that making such a pipe line is a fair bit greater an engineering challenge then building a climber. The pipe line will be only able to move up or down gasses while the climber will be able to carry a much greater variety of materials back in forth. One must ask when we reach this level of engineering sophistication will it make sense to pump fuel from earth or will we be better off obtaining the fuel from space.

GCNRevenger · 2004-11-20 10:17:11

Nooo I don't think it will ever be built. See, if you need somthing like 4,000-5,000 individual pumps to reach geostationary orbit, the weight of them plus the weight of the metal waveguide tube, plus the weight of power conversion equipment on each pump plus the weight of valves and other safety equipment, and lets not forget the actual pipe and the gas itself will be so great that no cable of reasonable size could support it all.

The pumps will each have to be able to move around two metric tons each and every single day to compete with a SMALL two-climber/two-rail elevator capable of lifting 5MT every three days. If you were to build an elevator strong enough to support the literally thousands of heavy vacuum pumps and associated hardware, I will bet good money that the same elevator using climbers would slap it silly.

There are three fundimental problems with the whole idea of a pipline to the sky:

1st: You are fighting gravity with gas pressure, that is, you are relying on the uncompressability and kenetic motion of gasses in order to efficently move gas up the pipeline. This is stupid, because gasses compress very easily, and the kenetic motion of the gas molecules is too low to reach very high to the next height step.

2: Continuing to embrace the lie that carbon nanotubes have fantastic and even magical do-anything properties. This is simply not so. They have a limited maximum theoretical mechanical strength like everything else, and this strength compared to the weight of a hypothetical 24,000mi high cable is not much higher. Hence, you will require a vast quantity of them to make a strong enough cable for a pipeline.

3: Hydrogen gas, the only gas worth sending up the pipe, will chemically attack the pipeline itself. On Earth, metal pipes are pretty good at holding it back for a while, but Hydrogen will attack carbon more easily then metals and the pipeline will simply break down. CNTs also do not have the energy level banding that metals do, so they cannot be used as a waveguide pipe either.

John Creighton · 2004-11-20 10:29:35

If you were to build an elevator strong enough to support the literally thousands of heavy vacuum pumps and associated hardware

I do wonder if this equipment can be made light enough.

3: Hydrogen gas, the only gas worth sending up the pipe, will chemically attack the pipeline itself. On Earth, metal pipes are pretty good at holding it back for a while, but Hydrogen will attack carbon more easily then metals and the pipeline will simply break down.

How about methane. This would also give carbon which will be needed to build more space elevators.

CNTs also do not have the energy level banding that metals do, so they cannot be used as a waveguide pipe either.

Can you explain this a little more to me. I though all you needed for a wave guide was a boundary that could not support a voltage due to the conductivity of the material. Or a change in the speed at which the wave travels.

John Creighton · 2004-11-20 10:34:47

You are fighting gravity with gas pressure, that is, you are relying on the uncompressability and kenetic motion of gasses in order to efficently move gas up the pipeline.

When you compress the gas with the pump it will expand and do work by raising the gas to a higher altitude. If the gas looses heat well it is compressed it may regain some energy as it expands for the sun. I am not sure what the net effect will be in terms of efficiency. But with thousands of pupms small efficiency losses will be bad. Do we really need thousands of pumps? Time to do more math .

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#1 2004-11-19 11:01:01

Re: Upside down "U" shaped manometer carbon nano tube

#2 2004-11-19 11:27:31

Re: Upside down "U" shaped manometer carbon nano tube

#3 2004-11-19 11:31:47

Re: Upside down "U" shaped manometer carbon nano tube

#4 2004-11-19 12:37:09

Re: Upside down "U" shaped manometer carbon nano tube

#5 2004-11-19 12:40:04

Re: Upside down "U" shaped manometer carbon nano tube

#6 2004-11-19 13:07:09

Re: Upside down "U" shaped manometer carbon nano tube

#7 2004-11-19 13:13:21

Re: Upside down "U" shaped manometer carbon nano tube

#8 2004-11-19 13:26:17

Re: Upside down "U" shaped manometer carbon nano tube

#9 2004-11-19 14:11:55

Re: Upside down "U" shaped manometer carbon nano tube

#10 2004-11-19 14:23:17

Re: Upside down "U" shaped manometer carbon nano tube

#11 2004-11-19 14:48:36

Re: Upside down "U" shaped manometer carbon nano tube

#12 2004-11-19 14:51:21

Re: Upside down "U" shaped manometer carbon nano tube

#13 2004-11-19 14:57:27

Re: Upside down "U" shaped manometer carbon nano tube

#14 2004-11-19 15:05:33

Re: Upside down "U" shaped manometer carbon nano tube

#15 2004-11-19 15:23:16

Re: Upside down "U" shaped manometer carbon nano tube

#16 2004-11-19 15:26:53

Re: Upside down "U" shaped manometer carbon nano tube

#17 2004-11-19 15:31:23

Re: Upside down "U" shaped manometer carbon nano tube

#18 2004-11-19 15:36:18

Re: Upside down "U" shaped manometer carbon nano tube

#19 2004-11-19 17:55:07

Re: Upside down "U" shaped manometer carbon nano tube

#20 2004-11-19 18:15:53

Re: Upside down "U" shaped manometer carbon nano tube

#21 2004-11-20 09:42:15

Re: Upside down "U" shaped manometer carbon nano tube

#22 2004-11-20 09:48:50

Re: Upside down "U" shaped manometer carbon nano tube

#23 2004-11-20 10:17:11

Re: Upside down "U" shaped manometer carbon nano tube

#24 2004-11-20 10:29:35

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#25 2004-11-20 10:34:47

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