Is there an optimum load for a turbine to operate most efficiently?

[MrTurtle]

Specifically Francis turbines. I'm sure there is an ideal flow rate which gives the maximum efficiency, but if you had one flow rate to work with would there exist an ideal amount of applied load which would result in the most efficient conversion of energy? Say you kept all other things constant but changed the friction resisting the rotation of the turbine, would there be an optimal friction value that allows the maximum amount of potential and kinetic energy to be captured? Or would the most efficient design be the one with the minimum amount of friction?

 

[itsmoked]

Minimum friction.
Yes, there will be some point of maximum efficiency. It won't be anyplace you can reasonably find and use. The electrical load point normally isn't easily moved around so the best you can do is have the load you have and run just enough water to maintain that load point which is the best efficiency at that load point.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[NRP99]

Yes, minimum friction/0 friction could do the magic of getting ideal efficiency in any machine.

But making complete system frictionless is impossible and when trying to achieve we may incur costs which may defy logic to use that turbine/system for power generation. Even if we spend money to do everything to lower down friction, there would be still some amount of friction present in system.
How can we remove the frictional losses in penstock and components mounted before water enters turbine (which reduces the input energy) and inside turbine even if we use very high surface finish components/efficient bearings (which reduce the output energy)? Even if we use air bearing, the air-friction would contribute to the loss of energy. Same thing for generator losses.

So with whatever possible economical ways we can reduce friction, that can be beneficial in achieving best possible efficiency.

 

[GregLocock]

I doubt you'll improve efficiency by adding friction, but there is the nub of a good idea there, called impedance matching.

Cheers

Greg Locock


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