Looking for cheapest Trompe Designs

Discussion in 'Designing, building, making and powering your life' started by purecajn, Nov 9, 2011.

  1. Wolf_rt

    Wolf_rt Junior Member

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    Its certainly possible, but would have to be nearly 3000 feet deep.... quite a engineering feat.

    even if you could get to 500psi and double it with heat... What would you do with it?

    it would cost 10's of thousands for piping and storage.
     
  2. Pakanohida

    Pakanohida Junior Member

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    There has to be something we are missing with regards to PSI of air pressure and the depth the water has to drop prior to dropping off the air. These depths sound insane & not wise to approach.
     
  3. purecajn

    purecajn Junior Member

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    yer, hw do you maitenance this beast of yours? and we are moving away from the post title of "cheapest." was hoping to find the most cheapest/most economical power source for a househould.
     
  4. Wolf_rt

    Wolf_rt Junior Member

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    well if you have 200ft of fall on your property you've found it.

    if you have to drill a 200 ft well with a kick at the bottom its probably not that cheap.
     
  5. Pakanohida

    Pakanohida Junior Member

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    I was talking with a friend last night at length, we reckon the depth is to increase cooling of the air and keep it that way. The venturi principle which is essentially what we are messing with is already in practice in salt water aquariums in the guise of "Protein Skimmers" which works the opposite of the Trompe. In a Protein Skimmer, the air goes up as the water goes down. This causes dissolved organics on the water surface to breakdown into a brown frothy disgusting looking stuff. You can find this exact action on any beach in the world at high tide, you will see a line of brownish foam floating on top of the water. The high tide generally deposits this waste onto the beaches.

    So, going back to the Trompe now, the system should be simple to capture. Pressure will be directly related to how well the air housing can hold air, its volume, etc.

    Thus, IMO, what we need to do first is not make the trompe device, but first figure out how to house the air cheaply underground, safely. Some thing everyone can do cheaply with materials on hand.
     
  6. Wolf_rt

    Wolf_rt Junior Member

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    The air will stay at whatever temperature the water is, and pressure will be directly related to height..

    making the chamber to hold the air is definitely the biggest engineering problem though for sure.
     
  7. Pakanohida

    Pakanohida Junior Member

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    I disagree. Air temp is cooled on the way downwards, and air temp is maintained by being surrounded by cool earth in the collection chamber. Pressure is related to height, but also to collection. When air is released you have less pressure, and more water in the chamber.
     
  8. Wolf_rt

    Wolf_rt Junior Member

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    when air is released, you will have less air, same pressure, because it still has the same amount of water sitting on it, which is what provides the pressure.

    Once the air has been collected at the bottom, it may stabilize to the temp of the surrounding earth, which may be cooler than the water, but that has nothing to do with the air being isothermally compressed, if you heat or cool isothermally compressed air after it is compressed it is still isothermally compressed.

    the contrast is against a piston compressor, which will burn you if you touch the output pipe while the compressor is running.

    The volume of the storage will not affect air pressure, because if it isn't full of air, it will be full of water. the air/water pressure will be equal at whatever depth you choose, and can be calculated the same as pump head. ie, the 35psi per 15 ft figure you supplied.

    If the 'tank' at the bottom, is leaky, that will certainly cause a drop in pressure, and likely failure of the whole system.

    The air pressure will vary slightly (in equal proportion to the 15psi-35 foot ratio) as the volume of air increases and forces the water level lower, until the vent level is reached.

    I found this more accurate way to determine pressure on wiki...

    Pump curves in feet of head can be converted to pressure - psi - by the expression:
    p = 0.434 h SG

    where
    p = pressure (psi)
    h = head (ft)
    SG = specific gravity
    so:

    p= 200 ft (for example) measure from the surface of the water entering the trompe, to the bottom of the vent pipe (or the top of the bend in the input shaft, if no vent)

    SG= 1 (for fresh water at 60def F)

    so 0.434 x 200 x 1 = 86.8psi for a 200 ft drop.


    As far as creating the tank goes, only the section above the vent level needs to be airtight, if water leaks out the bottom it won't effect the operation of the trompe.
    also, the pressure of the earth pressing against the sides of the tank increases in the same proportion as the water/air pressure, the further you go down so a particularly strong tank is not required, as long as it is completely buried.

    As to how to make a spot for the tank 200ft down in the earth.. its got me stuffed.
    I guess you could drill a well large enough to admit a person who could hollow out the bottom of the well as required, would be prohibitively expensive though.
    the other option i see, is to build the whole trompe into the side of a cliff/steep hill.. the storage tank would have to be able to handle the pressure on its own though, as there would be little soil above it.
     
  9. Wolf_rt

    Wolf_rt Junior Member

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    I had an idea.... if you drilled two wells to intersect at the bottom, then lined and capped one of the wells to act as a tank, with the vent and output coming thorugh it, it may work.

    [​IMG]


    With such a vertical tank though, the air pressure would be quite variable, depending on the water level in the capped well.
     
  10. Pakanohida

    Pakanohida Junior Member

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    I disagree. We are supposed to have a chamber that fills with water and air, that's the beginning basis of the whole system!! As the air fills the chamber, the water level goes down till it is under pressure.

    Isothermally cooled is just fancy way of saying the air & water gets cooled by the earth as it travels down the pipe to the collection chamber
     
  11. Pakanohida

    Pakanohida Junior Member

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    Here's the basics re-drawn from the PDM.


    [​IMG]

    Uploaded with ImageShack.us
     
  12. Wolf_rt

    Wolf_rt Junior Member

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    Remember when bill describes the air bubbles getting smaller as they go down the tube? that's because they are being compressed.

    the air is as compressed as it is going to get while the bubbles are still in suspension in the water stream.

    the tank is there to collect the already compressed air.

    any air (any material, even the soil) under a column of water will be compressed at the rate described above, the trompe is just an easy way to get air under a column of water.

    This is physics. you can prove the concept to yourself through a simple experiment.
    take a coke bottle and cut the bottom off, and stretch a balloon over it. take the device to the local pool, and dive to the bottom with it. the previously flat balloon will be sucked into the bottle as the air is compressed.

    What do you think of the two wells pic i posted as a simple way to form the tank underground? the water goes down the pink pipe, and the water comes back up the same well outside the pipe, in a similar fashion to the pic in the PDM.

    [​IMG]
     
  13. purecajn

    purecajn Junior Member

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    good job, u 2 are really comming up with gravy. any chance of a quick-n-easy tank lvl chk that can be hacked into it?(as I don't think a pressure guage is as easy) Handy to have a quick visual on air lvl.
     
  14. Pakanohida

    Pakanohida Junior Member

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    Physics with water is tricky. Water, IMO, acts like it is alive.

    Your bottle experiment is a generality IMO as well. I am a diver and understand compression underwater, which is very different on land.

    At 10 meters below the sea surface you experience 2 atmospheres of pressure, or 200kPa, however at 30m or 100' you will experience 4 atmospheres, but at 40m it jumps up to 5 atmospheres & then it starts getting bad. Last time I went a tour of a cave system on land I didn't experience any pressure problems what so ever. Follow my simple reasoning?

    Couldn't the pressure be a result of air and water dropping via gravity from a large source into a small pipe. I mean we are going from a funnel using the venturi principle to pull the air down. Granted, I am a layman when it comes to physics, but I do understand water very well from other jobs & life experience. Vicktor Schauberger's works helped too.
     
  15. Wolf_rt

    Wolf_rt Junior Member

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    Yeah i see what you mean about the cave, but what about a combination of the two?

    If you added air to the 'cave' here until it started spilling out, the air pressure would HAVE to be 100psi as far as i can see.
    [​IMG]


    How about a simple float that passes through the vent pipe for a level check?

    [​IMG]
     
  16. purecajn

    purecajn Junior Member

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    simple float would work, but it would need a spring of some sort for line tension. Then again, when said string breaks/rots, or the float becomes unattached/sinks how would one maintenance it? If your gonna use a tube to feed the line thru then why not simply drop a stick down for your level chk? like the Petro. stations do it for their tank, only with a tube feed whereby compressed air can't escape. Or even a stick perminently in said tube with the float attached to the bottem whereby the stick rises and falls with the water. that way the float level system can simply be pulled out and replaced if needed.

    Also, is there a way to download a whole thread? as I'd like to do same when this thread is complete.
     
  17. purecajn

    purecajn Junior Member

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    A shallower system could be made whereby said chamber could be physically/mechanically compressed for more pressure when needed for short periodsof time. This would releave the need for depth in a non-commercial environment, no? but would the bottom press up whereby temporarly closing water outlets/inlets temporarely, or would the top bress downward. Two pipes ( ? ) , one fed into the other.
     
  18. Wolf_rt

    Wolf_rt Junior Member

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    good idea with the stick... the tube is there anyway for the vent.

    I use a program called PageNest to download web pages.

    any further compression of the air would be best achieved by a regular compressor above ground i suspect.

    The system you suggest would be mechanically complex, and as you said, maintenance is a major drama underground.
     
  19. purecajn

    purecajn Junior Member

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    how much air pressure would one really need for a residential home? I think that is a major point not being taken here. If say only 10lbs or less of pressure is actually needed to run what ever then an above ground system or even ground lvl system could be used in which extra compression would be fesable in emergancy situations all the while making maitenance extremely easy..
    And why would the air chamber tank have to be deep anyway. as long as the feeder and exit tube are deep the air storage can be placed anywhere, even above ground. Well as long as you have something that can handle your presure created. A lot less digging to boot
     
  20. Wolf_rt

    Wolf_rt Junior Member

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    anything under 80psi is going to be pretty useless for running any sort of vein type air powered motor. (air tools)

    I'm unsure what pressure air(steam) turbines require??? (for running a generator) but will definitely require large flow rate. Did some quick research and it appears that turbines are available that will run with as little as 50psi... will have a VERY high delivery requirement though. (not sure how to work this out as these systems are designed for steam... which may also produce exhaust velocity issues, as steam shrinks as it cools going through the turbine)

    Spray painting will require 50-60psi although LVLP guns will operate with as little as 25psi.

    refrigeration by just letting compressed air escape will require at least 80psi i suspect.. the more the better

    Hmmm, i wonder how hard it would be to comvert a regular compressor to run on low pressure high volume (LPHV) air power to create a small amount of highly compressed air. (would probably require a custom made air motor (fairly basic to make if you have machine tools) to suit the pressure).

    From what i can figure getting a (comparatively -to piston compressors) high volume of air is rather easy with a trompe.

    It may be worth having a play with Tesla boundary layer effect pumps?
     

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