Homebrewed Electricity > Hydro
My Jungle hydro project- 5kw pelton to power future eco-hostel
mab:
I think when i was looking into my pelton system it was stated somewhere that the optimum spoon velocity was approx 1/2 the jet velocity for max power xfer to the wheel; in practice it will vary slightly depending on the exact spoon shape and where the jet is actually hitting the spoon - if the water hits the spoon and comes off still with forward velocity the wheel's spinning too fast; if the waters coming off back towards the nozzle the wheel's too slow; if the water comes off sideways it's about right. In practice however, with my small wheel the water's going in all directions so fast I can't really tell TBH.
At the risk of being a pedant: the generator Sparweb showed looks like a Turgo wheel rather than a pelton (judging by the angle of the nozzles to the wheel); possibly H-hydro blue spoons? It may be worth considering a turgo - I found that it was possible to get a smaller diameter turgo than pelton which accepts the same max jet/nozzle diameter, which in turn allowed me to get higher shaft RPM (i only have 20m head). I say this as direct drive of the generator will always be more efficient than a transmission, and with one less thing to wear out. The efficiency of a turgo is comparable to that of a pelton i believe.
junglehydro:
--- Quote from: SparWeb on March 28, 2021, 01:59:54 PM ---Hi JH,
One thing to check is the volume of the flow in the penstock (Area * velocity) and compare with the nozzle flow volume (Area * velocity). Put that way, kinda obvious that they'd be equal, but the reason to point it out is to make sure it's considered in your math. It can give you a solved variable that otherwise wasn't certain. A few calculations to size up the nozzles, penstocks, and wheel in general, followed by experimenting with nozzle sizes, should allow you to tune in the generator to the point you're happy with it.
--- End quote ---
Yeah so I am pretty sure that we'll start with less water and a less than optimal power production, since we don't have enough length of pipe to feed the penstock with enough water for 5kw. But we don't need that much know, and it's something we can easily scale up in the future by adding another pipe to the water bay that feeds the penstock. and we'll have to adjust the nozzles probably a few times as we go up in flow. Right now I would settle with a constant 500-1000 watts so we can run everything we need to build our place.
--- Quote from: mab on March 28, 2021, 05:41:26 PM ---I think when i was looking into my pelton system it was stated somewhere that the optimum spoon velocity was approx 1/2 the jet velocity for max power xfer to the wheel
--- End quote ---
Yeah I remember reading that as well, that usually runaway(unloaded) speed is about double of the optimal speed. ( I think in powerspout documentation, so not sure if thats a general rule or applies to powerspouts only.) If I use the calculation from bigrock I come to about 2400 rpm unloaded, so then loaded would be 1200. so a 2:3 wheel ratio should do the trick in that scenario. I guess I should see if I can find a Tachometer to measure rpms somewhere once I have everything setup is still the most reliable way to figure out my true RPM.
bigrockcandymountain:
If you have the generator hooked up, you can just measure the frequency in hz for rpm indication too. A tach is a good idea though.
junglehydro:
Hi guys and girls a quick update here, with some new questions!
So I've decided to start a bit smaller with a creek that is quite a bit closer, but will dry up a bit in de dry season, so somewhat less production then. The big turbine is too much of a hassle with transport and infrastructure being such a problem at the moment, and that capacity will not really be needed for a few years anyway..
I am going to install a powerspout in a closer creek with 85m of head and am thinking about hooking it up to our current solar system.
Am I correct in thinking that basically all it needs extra is a diversion load so my turbine won't overspeed?
I am thinking about hooking up a Xantrex c40 in diversion mode.
I now have a all in one inverter chargecontroller, a powest 3kva, hooked up to two 100ah 12v lithium batteries
The turbine will generate about a 1000 watt continuous for about 9 months a year and then drop down to 400 watts at the minimum for the rest.
bigrockcandymountain:
1000w continuous is awesome anyway.
A c40 is only able to do 40a. I can't remember if you are 12v or 24v. At 12v you'll need to dump 83a and at 24v 43a. Either way a c40 is a bit small. Float voltage of a 24v system is 26v or so, so i guess the c40 might be ok. I like to oversize a bit but that's up to you.
If you are 12v, 2 c40s or something like that will do the trick but will be close to max just like 1 at 24v.
A ts45 tristar would give more margin for error and they have a better reputation.
Are you heating water with the dump load?
Good to hear from you again. I have been wondering how your project was working.
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