Is 3 ft of head worth 80 ft of 3 in pvc?

[countrykidd]

I have a a homemade turbine working (in the testing phase) on 12 ft of head, fed by 3" PVC. The 12 ft drop is over about 100ft. For test purposes, the 3" pipe starts from a convenient 3' high cement dam. The funny thing is that over the last 20 years the beavers built their dam 70' further upstream and it holds back 3 more feet of water than the little cement dam. (Which is good for the lake.)
What I am wondering (from what I've read on this site so far, I am pretty sure one of you guys know this off the top of your head) is "Is it worth it to extend the pipe another 80' upstream to the beaver dam to gain 3 more feet of head? The pipe would drop down the side of the beaver dam then run flat for 70' before dropping the next 12 ft.

I may have to go back to the beaver dam anyway because in a very dry summer the beavers make their dam pretty tight and only a trickle of water gets to our cement dam.

[hydrosun]

How many gallons per minute are you using? If you lose too much head in friction in the additional 80 feet of pipe it would wipe out any gain in head. The other concern I'd have is if the beavers would try to block  the pipe.
Chris

[countrykidd]

I'll have to get back to you on how much water I use because I am still playing with nozzle sizes and whether to use one or two.  My turbine is homemade and not a design really recommended for low head situations. I thought I'd try it because it seemed easy to build. May tackle a Banki later.



As for the beavers, yes they are driven to plug rushing water. For awhile, they tried to plug the gate in the cement dam , too.  The intake will have to be under water. No noise.. no beavers .... I hope.

[nick1234]

what is the volume of water going over the dam gate
 how much of that flow can you use
 that will determine the size of the pipe you need 
the more flow the more power
the flow and pipe size will determine if the extra 70 ft has merit

[ghurd]

Cool!
I would like to see a photo of that thing standing still.
Looks interesting.
G-

[countrykidd]

Thanks! Here's a pic that caught the turbine in stop motion. I have a video of my garage testing and one of the on site testing but not sure how to share them here.

[ghurd]

I do not believe videos can be posted here.
Start a photobucket or youtube account, then post a link.  That's what I did.

I suppose it is not a good design... but by golly, it IS spinning!
G-

[countrykidd]

Should see it spin with no belt to the PMG, that's when you find out if you got the turbine balanced! This weekend I am trying a few modifications, maybe get a RPM reading and ballpark the gal/min.

Currently, there is a 9" pulley on the turbine shaft and a 2" on the PMG. The initial testing resulted in 31 vdc (open circuit) and 2.2 amps when hooked to a deep cycle that was basically flat at 12.0 vdc. The battery was reading 13.7 when we shut it down 5 hours later which seems too quick for 2 amps of charging.

[ghurd]

13.7V.
Could be the battery is getting old.  If it was sitting at 12.0V very long, it is a sign it is not tip-top condition either from being abused (from being left standing at 12.0V?) or just worn out.

And part of the voltage is surface charge.
It does not take a whole lot of amps (proportional to the battery capacity) to get a charging battery up to a terminal voltage of 13.7V.

Looks like fun.
G-

[hydrosun]

I can't tell from the picture if there is any kind of nozzle at the end of the pipe. If you are running the three inch pipe directly at the turbine you are throwing out the power of the pressure from 12 feet of fall.  The maximum power that can be moved by a pipe is when 40% of the pressure is lost. Beyond that the added gpm is offset by the loss of head. So you would find that you would get more power by using less water by restricting the opening at the end. Ideally that restriction would be a smooth transition to a smaller diameter.  I'd start with a  1 inch diameter opening that would let out about 70 gpm and lose about 1 foot head in 100 feet 3 inch pipe. So a 50% efficient turbine would produce about 70 watts. Your turbine looks similar to what I made 20 years ago using  pieces of metal in slots cut into the pulley. You may want to put more slots closer together to avoid having the water missing the blades or hitting at less than perpendicular.  Using a 1 inch nozzle would allow you to use a smaller diameter pulley and then have the rpms higher for a closer speed match to your generator. And adding the 80 feet pipe to get 3 more feet head would make sense at 70 gpm.
Chris

[jlt]

You could get more output by decreasing the diameter of the turbine,and making it direct drive .your probably losing a third of your power in the belt drive.You don't say what kind of gen. you have. A turgo  wheel will take more water and . they are not to hard to build.just put your blades at 90 degrees  from how they are now and space them closer together.If you have enough water a second line up to the beaver dam .and hooked up to a second nozzle . and then shut off the other one when you don't have enough water 

[countrykidd]

Thanks for all the input. Very much appreciated. Gives me some ideas on which changes would be to the best.
 I have attached a few pics of my on site testing to better describe my set up.

I do have a 1 1/2" "nozzle" at the end. I tried a 2" but measured less output and went back to the 1 1/2" .

You are right about the belt and losses associated. We are going to try a flat belt to reduce the losses.

 I went with the pulleys so I could easily change ratios to get the best RPM to torque. After the initial test I found that I could change the bottom pulley from a 6" to a 9" and the top one from a 3' to a 1 1/2".  This change boosted RPM on the PMM but still had enough torque to keep running when load was applied.

The main reason my hub/blades are so big is that I wanted blades big enough to catch the output from a 1 1/2" nozzle but I would put more blades on if I were to build another one.

The PMM, I am using, was donated and I don't know much about it. The information plate on it says rated for 200 watts and 2.5 amps. It is pretty small and you can just feel the magnets cog when you turn it by hand.
Recent testing measured 46 VDC (open circuit) and 2.6 amps when charging a deep cycle battery. Maybe that's all I'll get out of it? How many watts is that? Is it 2.6 X 14 = 36.4 or is it calculated as  2.6 x 46 = 119.6?

Once again all input is appreciated.

If interested I have posted a video of the unit running at http://www.youtube.com/watch?v=XQ3ysu0Nx-A

[hydrosun]

A 1 1/2 inch nozzle will let out about 150 gpm at 10 feet head and 100 feet 3 inch pipe will lose 4.5 feet head at 150 gpm.  So that leaves about 7.5 feet head. But really a bit less gpm and a big more head, so a close estimate. A 50 % efficienct turbine would produce about 110 watts. You are actually producing 2.6 amps into a 13 volt battery or 33 watts. So about 15% efficient. Your open circuit voltage should be about double the loaded voltage. If not you might want to change the pulley ratio to get that. Could you cut slots in between the present cups and add more cups to the existing turbine?
 The small size of the wire in the motor rated at 2.5 amps may really limit your output. As far as your original question, running an added 80 feet of pipe running 150 gpm would lose more head than the 3 feet potential. You'd get less power than now. The only way to change that is to use a bigger pipe. But even a 4 inch pipe loses 2.5 feet head per hundred feet pipe. So your best bet to make improvements is in the turbine and motor.  Using a turgo and slower speed motor should allow you to direct connect the turbine to the motor for higher efficiency. What you would be shooting for is about 100 watts max.  Have fun playing in the water. I spent a lot of time doing the same before going to a Harris PM turbine and then didn't have any more fun trying to make improvements.
Chris

[frepdx]

countrykidd, that's some great improvisation, nice work.

Did you get a flow rate? I skimmed above and may have missed it. You need that to calculate pipe losses before you know if the extra piping for three more feet of head is worth it. Here's an on-line calculator; http://www.freecalc.com/fricdia.htm

Also, once you get the flow rate check the losses in the nozzle tube. Might be worth it to eliminate and make a nozzle from the 3" transition.

[scottsAI]

Nozzle looks wrong, can't see detail at the actual very tip.

Purpose of a nozzle is to convert pressure to velocity.
As I see it:
Your nozzle is the transition from 3" to 1.5" turbine is several feet from the transition! Not good.
As already mentioned a smaller nozzle may produce more power.

To test piping efficiency add a sight glass 1 inch before the Nozzle. (clear tube to see water level (pressure))
Pressure or level should be as tall as the water supply.
If the level is less this represents head losses in the pipe.
Sight glass water level represents the actual power available to your turbine.

Have fun,
Scott.