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Making ancient time water wheel to lift water

  1. Nov 27, 2014 #1
    I have one project of developing setup to lift heavy water at some height. A setup that take less energy as compare to traditional water pumps. I was searching on net and I found giant "water wheels" of ancient times to lift water.

    Like this one http://en.wikipedia.org/wiki/Norias_of_Hama

    Is this possible to rotate this with electric motor and make setup to lift water which is efficient than traditional water pumps?

    I was thinking that due to circular motion, inertia, momentum, centripetal force, etc might be this can be more efficient than traditional water pumps!. I thought it may require more power to move it from rest but once wheel gets momentum then it requires less power as compare to moving from rest.

    For example:
    Wheel diameter: 30 meter
    Water mass: 100,000 kg per round
    Speed: 1 round in 10 minutes
    Driven by: electric motor

    I don't have any physics background so please excuse me if you feel this is stupid idea. http://www.thescienceforum.com/images/smilies/icon_rolleyes.gif [Broken]

    Please give your opinion on this?

    Shaks
     
    Last edited by a moderator: May 7, 2017
  2. jcsd
  3. Nov 27, 2014 #2

    Danger

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    I'm not sure about that. While I don't know any math, my intuition thinks that the large diameter would also make for an awful lot of leverage on the loaded side to overcome.
     
  4. Nov 28, 2014 #3
    Wheel diameter: 30 meter
    Water mass: 100,000 kg
    Speed: 1 round in 10 minutes
    Driven by: electric motor

    100,000 kg water = 26,417 gallon per round (1 gallon = 3.78541 liter/kg)
    26,417 gallon / 10 minutes = 2,641 gallon per minute (gpm)

    I found formula of calculating pump power according to gpm.
    Motor HP = (height in feet * gpm) / 3960
    Motor HP = (98.42 x 2641) / 3960 = 65.64 HP = 48.95 KW

    So if traditional pumps are used to lift 2,641 gpm then estimated 48.95 KW motor is required.

    Any idea if same amount of water is lifted by water wheel then how much electricity will be required?

    I believe that moving wheel from rest to required speed will take same electricity but once wheel get momentum then it should take less electricity to keep that momentum/speed?



    Shaks
     
  5. Nov 28, 2014 #4

    Bystander

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    Only if you leave the water on the wheel, which defeats the purpose.
     
  6. Nov 28, 2014 #5
    Explain with some logic, why its not possible?

    Shaks
     
  7. Nov 28, 2014 #6

    Bystander

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    The momentum of the water on the wheel is lost at the top, and you are constantly having to "replace" it.
     
  8. Nov 28, 2014 #7
    :confused:
     
  9. Nov 28, 2014 #8

    A.T.

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    That is the modern version of such devices:
    http://en.wikipedia.org/wiki/Hydraulic_ram

    I doubt it. The whole point of these wheels was to use the energy of the flowing river. But if you want to use electric energy, the current electric pumps are already the result of decades of optimization for this purpose.

    PS: I think you don't really mean "heavy water", do you?
     
    Last edited: Nov 28, 2014
  10. Nov 28, 2014 #9
    You pointed a good thing. :)

    The point where I am seeing a difference between traditional pumps and water wheel idea is the following:

    1. Traditional pumps are immediately stopped when power is switched off but wheel is in circular motion so even electricity is switched off then still wheel will be in circulation for a few seconds due to its momentum until air, water and other frictions don't overcome.

    2. Due to circular motion "centripetal force" helps against gravity, is this true?

    Heavy water = big amount of water :)

    Shaks
     
  11. Nov 28, 2014 #10

    jbriggs444

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    1. Any effect that you get from residual motion as the wheel slows down after power is turned off is "paid for" by extra effort that was required to get the wheel moving when the system was started up. There is no free lunch.

    2. Again there is no free lunch. Energy is conserved. There is no point in looking at complicated machines and hand-waved explanations to find the place where this manifests. Any extra lift that comes from "centripetal force" or any other effect will have been paid for by extra effort somewhere and somehow.

    If the water moves from bottom dead center to top dead center and is acted upon by "centripetal force", that centripetal force will have worked to oppose gravity for the first half of the movement and to assist gravity for the second half. That's how it balances out for that particular scenario.
     
  12. Nov 28, 2014 #11

    russ_watters

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    You have it backwards. An old style water wheel does not utilize centrifugal force, but a new style pump does.
     
  13. Nov 29, 2014 #12
    A.T., you gave good idea of Hydraulic ram pump and running wheel with "flowing water/river" and I am thinking to use both as combination.

    The first priority is to "rotate water wheel" with "flowing water". Now the question is how much water required to rotate such wheel? I mean following:

    1. How much water flow required
    2. Above water flow can rotate how big wheel
    3. How much water can be lifted in one round

    I think this is good idea, I created one diagram of my idea regarding flowing water.

    2m782zm.png

    Will this work i.e. we can create slob to create pressure in water flow so wheel may be rotated but the question is how to measure force of flowing water?

    How to measure force of flowing water or kinetic energy or potential energy of flowing water?

    Any idea on this?

    Shaks
     
  14. Nov 29, 2014 #13

    russ_watters

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    The pressure is expressed in the height it fell. The energy is pressure times flow rate. So what exactly are the requirements?

    I really don't think you are recognizing just how difficult and expensive it will be to build a 30m water wheel.
     
  15. Nov 29, 2014 #14

    jbriggs444

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    Looking at the diagram, it seems that your scheme is to use water-powered water wheels. The first wheel uses a 1 meter downward slope to power a wheel that lifts water by 30 meters (net 29 meters). Energy conservation requires that the fraction of water lifted by this wheel can be no more than 1/30 of the total flow.

    The next wheel uses another 1 meter downward slope to lift the water by 31 meters (net 29 meters after the two drops) Energy conservation requires that the fraction of water lifted by this wheel can be no more than 1/31 of its input flow.

    If you wanted to get (let's say) 99% of the water to be lifted by 29 meters you would need to allow 1% of the water to fall through a total of about 2900 water wheels ending with one that is roughly 2.9 kilometers in diameter.

    Then you'd still need to somehow get enough water to the top of your 2.9 kilometer mountain (or up out of the bottom of your 2.9 kilometer deep wheel well) to make up for that 1% leak rate. The efficiency losses in such a scheme would be enormous.
     
  16. Nov 29, 2014 #15

    russ_watters

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    Oh, requirements were in the first post: at 50% efficiency, that's about 90 kW. Its a pretty high flow rate and lift.
     
  17. Nov 29, 2014 #16
    You mean that one wheel can lift around 1% of total water flowed under the wheel? Can you copy formula here?

    I am looking to measure the force of flowing water in these mini canals. For example if canal is 5' wide (or wheel width +1 feet extra) and 5' depth and 10-20' long. We can measure how big wheel this water can rotate if we can measure the force of flowing water.

    Shaks
     
  18. Nov 29, 2014 #17
  19. Nov 29, 2014 #18
    Your question is not answerable in this forum. You are not posing a problem in physics; you are posing a problem in engineering and economy. We can discuss the principles water wheels and pumps; we could even figure out estimates of their efficiency. But a "minimum cost" design is a totally different beast. For example, from a "minimum cost" standpoint your idea that "these wheels will cost one time" is false. They will have wear and tear; they will need maintenance. It is one thing to maintain a compact device, even high tech, and quite another to maintain a huge structure.

    From the engineering/economic point of view, your question is invalid to begin with. Before you literally go inventing a wheel, you should get a firm grasp of the contemporary technology used to lift water and what costs its use incurs. Knowing the cost structure, you can pose valid questions: how can I optimize the costs? Where could I save most?
     
  20. Nov 29, 2014 #19

    sophiecentaur

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    If your initial source of energy is from moving water then there is an attraction in avoiding the inefficiency of transforming it to Electrical and then back to Mechanical again. A large,slow water wheel could be used to drive a 'conventional' pump using gears of a belt to produce a faster rotating small pump directly. But, as voice says, the whole project would need to be costed - for both Money and Water flow. If there is plenty of water available to produce your motive force then it's FREE!, which could be highly relevant.

    One way to look at the feasibility would be to decide how much water flow you need from your pump and what height it needs to be lifted. That will give the required Power (=mass per second times g times h). Then you need to estimate the amount of available Hydro power you have - (Available water mass per second times g times drop). You would be lucky to get as much as 10% efficiency out of an overall system without some cleverness, I'd bet so you can check whether your available Power In is ten times the wanted Power Out. If not, then think again.
     
  21. Nov 29, 2014 #20

    Danger

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    One thing that you might investigate is attaching an auger (Archimedes Screw) directly to your paddle wheel. It still won't be very efficient, but at least it would remove the need to translate the energy from rotational through other forms.
    I suppose that construction costs could be minimized if you sneak into an amusement park at night and steal their Ferris Wheel...
     
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