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Low rpm high torque water wheel  RSS feed

 
Makin Itapin
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So this is my question. If I have a very wide water wheel, say 12ft wide vs 1ft wide. Will that give high torque?
 
allen lumley
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- Wider ( and possibly deeper 'Buckets" ) will allow you to catch more of the water flow than a narrower wheel will, Depending on your location, the time of the year,

and the resulting amount of stream flow you could have more water running in the stream than you can use.

Does your site provide year round flow, or can you place a Dam upstream from your water wheel to hold back some/most of the total flow to hold it in reserve for

your local dry period(s)

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For the good of the crafts ! Big AL
 
Rhys Firth
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Not really, Torque comes from the lever arm length, a 12 foot diameter wheel 1 foot wide would have more torque than a 12 foot wide wheel 1 foot in diameter.
 
Dillon Nichols
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Rhys is right; going from a 1ft diameter to a 12ft diameter would also lower the RPM by a factor of 12, assuming the resistance of the wheels is equal.

The other thing to keep in mind is that an overshot water wheel will provide better efficiency than an undershot, providing more bang for your flow... but this does limit wheel size in some situations. I think a breast-shot wheel is somewhere in between for efficiency.
 
Makin Itapin
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Thanks everyone. That's what I was thinking. It's a wide but somewhat shallow river. I'm in a great spot thou. There was a dam there at one time. So almost all the stone wall is in tact. Even in a dry season there should be plenty of water for this. I'm thinking as well because the river drops about 12-15ft naturally over 50-75 yards I can rout a portion of water in some type of aqueduct to my wheel and posibably hide the wheel under ground completely if not partially. Next question is how big of a wheel X water do I need for 2,000Watts wheel?
 
Dillon Nichols
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The potential HP of a water wheel is apparently Head(in feet) * Flow(In cubic feet per minute)/540. (http://www.waterwheelfactory.com/horse.htm)

If your entire generation process (from flowing water, through the water wheel, through the generator, through the wiring, through the charge controller, and back out of the battery bank and through the inverter... or whatever your system is) was 50% efficient, you'd need about 5.2 gross HP to make your 2KW.

So, to work back from that, and your head of 15ft: 5.2*540/15=187.2CFM flowrate, or about 1400 US Gallons per minute. So, you'd need a wheel big enough to pass that volume of water... assuming you have that much flow available.

How big that is in actual dimensions, I have no idea... and that 50% efficiency is just a wild guess, too.


2000 watts continuously is quite a lot of power; do you have extravagant power needs? Are you planning to have a battery bank charged by this power? Even a relatively small battery bank would allow for heavier loads for short periods of time, lowering the wattage required to be continuously generated...


EDIT: Found this, which explains how to determine sizing... also contradicts the previous power calculation. Hmm... http://www.backwoodshome.com/articles/behrens18.html
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