Micro Hydro Turbine, pressure and head, efficiency
Micro Hydro Turbine, pressure and head, efficiency
(OP)
Hi,
I have a question regarding the calculation of turbine efficiency.
If there is a certain head available at a hydro site, say 20m then the pressure will be approx 2 bar. However the pressure at the inlet of the turbine will be lower than this when the turbine is running becuase of the flow not being entirely restricted, say 1 bar.
So when calculating the amount of power in the water to find the turbine efficiency, should the potential head of 20m be used or 10m (the head equivalent of 1 bar)?
Cheers
I have a question regarding the calculation of turbine efficiency.
If there is a certain head available at a hydro site, say 20m then the pressure will be approx 2 bar. However the pressure at the inlet of the turbine will be lower than this when the turbine is running becuase of the flow not being entirely restricted, say 1 bar.
So when calculating the amount of power in the water to find the turbine efficiency, should the potential head of 20m be used or 10m (the head equivalent of 1 bar)?
Cheers





RE: Micro Hydro Turbine, pressure and head, efficiency
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"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: Micro Hydro Turbine, pressure and head, efficiency
Ok thanks, that is helpful but I think I phrased exactly what I was trying to ask quite poorly.
Say for example if you have a substantially large 20m high storage tank, and at the bottom of the drop you have a ball valve connected to the end of the penstock pipe with a pressure gauge one side, and open to atmosphere on the other side, when the ball valve is shut the pressure will read appxox 2 bar. If the ball valve is then opened the pressure will obviously drop to a lower value, is the head still constant at 20m, and just the pressure is lower?
RE: Micro Hydro Turbine, pressure and head, efficiency
RE: Micro Hydro Turbine, pressure and head, efficiency
This page shows it,
http://www.lmnoeng.com/TankDischarge.htm
Now, valve losses, which you may have some, if its not a full port, fully opened ball valve.
There can also be some losses associated with the water freely jetting out of the tank, but you might reasonably ignore those, if you had a turbine attached right there.
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"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/