Hydroelectric project (small drop and low flow)

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sicetaitsimple
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Re: Hydroelectric project (small drop and low flow)




by sicetaitsimple » 22/06/19, 15:28

Remundo wrote:oh yes, but of course ...

take me 20 L of water at the end of a bar 2m, you will see if it will not lower your arm ...

now you put 10 similar branches, we talk about it again ...

Obviously, if you have levels of pithecanthropic technology, the friction could prevail ...


20l? Each "cup" is filled for 40s? Indeed it does not turn quickly ....

On the bearings, we can actually advise Macadam the use of magnetic bearings, it may be a little complicated, right?
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sicetaitsimple
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Re: Hydroelectric project (small drop and low flow)




by sicetaitsimple » 22/06/19, 15:33

Ahmed wrote:The solution of Remundo I like it, but obviously with such a low flow, there is hardly any valid solution ... :frown:


The drawing is pretty ....
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Re: Hydroelectric project (small drop and low flow)




by Bardal » 22/06/19, 20:16

Yes, the drawing is pretty, although some impressionists have even better made the water mills ...

Without digressing too much towards aesthetics, these questions have been studied for at least two centuries by various scientists and engineers endowed with powerful means of investigation; all this has led to the abandonment, generalized in modern countries, of this type of "turbine" for low head; however, the market and the stakes are high: run-of-river power plants, tidal power plants, pico-plants ...

The reason for this abandonment is simple: only the valorization of a laminar flow of water allows to reach good yields for the production of electricity; out, the impeller works in principle in turbulent flow, with two stops of the fluid per cycle; it is also the same physical reason which made leave the wheels with paddles of the ships in favor of the propellers (or Voith-Schneider thrusters more recently).
All this led to large-sized machines, slowly rotating, therefore of low mass power and moreover delicate to monitor and regulate.

Very generally, all low-drop installations (below 10 meters) use Kaplan turbines, which are much more efficient and simpler in maintenance, or recently, various interpretations of the Archimedes screw. The Kaplan turbine is relatively tolerant in terms of variations in operating conditions if its initial optimization was correct, it requires very little pressure (at least 2 m) and requires little earthwork for small installations; only the screw can compete with it in some cases of very small fall, but it is still not widespread.

Finally, there are on the international market small units of 100, 200, 300 watts, ready to be installed, consisting of a Kaplan turbine in a steel tube, a regulated alternator and the hose which can be extended according to the drop; this type of machine, made in China obviously, was offered a few years ago for a few hundred euros by the house "Energie-soft" (which must still exist); I think it would be better for our friend to search the net for this type of machine rather than embark on the adventurous construction of a paddle wheel and ball bearings, as well as its sides, a reach in particular , which is no small feat.

Well, I should have started there:
https://www.energiedouce.com/hydro-turb ... 02510.html
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Re: Hydroelectric project (small drop and low flow)




by Remundo » 22/06/19, 20:34

the wheel above has a good hydraulic efficiency, especially if it turns slowly, it can exceed 80%, however it is not suitable for large flows because in this case it becomes too big and / or must turn too much quickly.

its disadvantage is also its slow speed of rotation unsuitable for generators of electricity, on the other hand its couple was a dream to operate old machines such as millstones or small sawmills.

As for making a reach to bring 0,5 L / s, it's a breeze: recover PVC pipes and nest them ...

but for 30 € electricity a year ... it takes passion.
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Re: Hydroelectric project (small drop and low flow)




by sicetaitsimple » 22/06/19, 21:34

Remundo wrote:the wheel above has a good hydraulic efficiency, .....


I write in a room which is as often about 2,7m under the ceiling, and therefore I visualize quite well the "wheel above" of 4m that you propose, 2/3 at my level and 1/3 at the upper level. And so I'm going to go and pour 0,5l / s upstairs, and nothing is going to happen except a flood!
If I'm wrong, the monster in question could potentially produce about 10W!
Please, stop!
Makadam simply asked a question about this forum for his particular case in describing it, the least thing if one pretends to know a little something is to tell him that technically and economically it's bullshit, after he will do what he wants.
Last edited by sicetaitsimple the 22 / 06 / 19, 21: 50, 1 edited once.
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Bardal
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Re: Hydroelectric project (small drop and low flow)




by Bardal » 22/06/19, 21:48

Oh ... And do you tilt your paddlewheel in a PVC pipe? I admit that I would like to see that.

And 80% yield? I am surprised. Is it a dream or the result of experiments?
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sicetaitsimple
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Re: Hydroelectric project (small drop and low flow)




by sicetaitsimple » 22/06/19, 21:55

bardal wrote:And 80% yield? I am surprised. Is it a dream or the result of experiments?


No, no, 80% yield for a bucket wheel is an internationally recognized value!
Is not it Remundo, will you flood us with irrefutable sources to prove it to us?
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Re: Hydroelectric project (small drop and low flow)




by Remundo » 22/06/19, 22:01

you are only provocateurs, but it's been a long time since I spotted you on this forum...

first I said 2 2m wheels were conceivable,

then there is no need to "fit" the reach in a wheel above, the reach tangent from the top.

finally, a very large wheel that rotates slowly on ball bearings has negligible friction losses especially as the force of the water is great.

The performance of the wheels above has always been controversial because many poor workmanship can damage the operation, everything is sensitive as the spill reach / bucket must be done as calmly as possible, then the buckets must keep the most water in descendant; the study of their form is essential, and the construction of a courier is sometimes necessary, but here too, the courier can sometimes do more harm than good ...

In the same way the evacuation of the water in the lower part must be clean (no splashing). But to handle 0,5L / s, a big wheel will not have any difficulty and will not clog, unlike a small pipe with a Kaplan in it.

The weak point of Makadam is its flow which is too low, but that is precisely why a wheel above is relevant, these are the rustic wheels adapted to low falls at very low flow (type of mountain stream). .. do not dislike, great connoisseurs hydraulic Sunday keyboard ...
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sicetaitsimple
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Re: Hydroelectric project (small drop and low flow)




by sicetaitsimple » 22/06/19, 22:33

Remundo wrote:you are only provocateurs, but it's been a long time since I spotted you on this forum.........
do not mind, great connoisseurs hydraulicians keyboard Sunday ...


Damned, spotted .... There I tremble ....
In addition, test engineer at the beginning of my professional life at the leading hydraulic performance pump in France and one of the best in the world at that time, Bergeron. It can still serve me on Sunday or Saturday.
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sicetaitsimple
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Re: Hydroelectric project (small drop and low flow)




by sicetaitsimple » 22/06/19, 22:46

Remundo wrote:The performance of the wheels above has always been controversial ....


Is that so? It's weird, you told us above that it could exceed 80%? Could one have inferred that between 70 and 80% it was roughly the norm?
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