Water Wheel hydro power? [RE-wrenches]

[Ron Macleod]

Hello Wes - Ian et.al.

	Sorry not to respond sooner - I've been out of town. 
	Wes - a "well designed" overshot wheel can achieve 80 - 85 % eff. at
the wheel shaft. One of their best attributes is they maintain eff. over
a wide variation in flow. It is also true that they cannot handle much
loss of head. 
	One reality is that to get these kind of eff. an overshot needs a
minimum of 12 feet of head.In a good design one needs 14 to 16 inches of
head over the "Chute" that delivers water to the wheel and about 4
inches of clearance between the wheel and tailwater. Two feet so far. If
the wheel radius is much less that 5 feet the buckets start to dump
water too high up the wheel and effectivly head is lost. Thus 12 feet.
	Other realitys are the low speed and high torque and massive wheel
weight (steel construction is the only way to go).With a prime mover at
say 12 RPM speed increase to a generator can be pretty lossy. A good
steel wheel with appropriate mechanical power tansmission and generator
is a pretty expensive deal. Example - 12 food diameter steel wheel - 40"
wide with shaft and bearings - say $14000.00 - power transmission
another $ 1000.00 - low speed Jacobs wind generator (270rpm - 48 volts)
$2200.00.
	So - anyway - figure the power available from your available flow and
head - and assume about 55-60% overall sys eff. water to wire.
	Water wheels are very cool and pretty to boot. In 20 years I've only
installed one - thus above #'s. I have just sold the same customer a
small francis turbine  with alternator which will match the output of
the wheel for less than half the cost. It runs at about 450 rpm and
weighs about 276 pounds as opposed to over 4000.
	Ley me know if you have more questions. - Best Ron
	 

Wes Kennedy wrote:
> 
> Hi Gang,
> 
> Anybody have any experience with calculating power available from a
> hydro site when using the overshot water wheel?  I remember reading
> an article in an old Home Power, but I can't find the formula.
> 
> Thanks!
> Wes Kennedy
> Evolutionary Technologist
> 
> "Your philosophy is not what you believe, it's how you live!"
> -j rubin
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