How to find out the minimum head required to install micro-hydro
A question from Rebecca:
To who it may concern,
I am a student in Sixth Form at Leicester Grammar School, I am working on an EPQ on a possible design for a hydroelectric generator that can be used on the vertical within a drainpipe system. This would allow it to be used on preexisting structures and should be easier to install than a typical micro-hydro scheme. I think that a cross-flow turbine would be the best for this project however I have been unable to find out what the minimum head is required for this. The other option for a turbine would be a Kaplan or propeller turbine, could you point me in the direction of which would be more suitable to use? I hope that you can help me to find this information out. Thank you very much for your time.
Thanks for your question which I have forwarded directly to our RedR KnowledgePoint experts.
Hope you get some useful answers soon!
Kind regards, Leigh
LC Jones RedR Member Volunteer Knowledge Point and Technical Support Services
Reply from Mike Innes, forwarded by RedR KP moderator.
Good luck with your project, Rebecca. As you've already discovered there are various options on the type of turbine you could use, and the minimum head varies with he type of turbine you choose (or are stuck with). I'm afraid the selection process is going to be a bit iterative.
For propeller or Kaplan turbines all of the blades of the impeller have to be in the flow; that is, the flow of water must fill the pipe in which the turbine is submerged. This can be hard to attain and difficult to maintain.
The crossflow turbine is an impulse type and can work with variable flow rates (within some limits). This article does a nice job explaining the pros and cons of the different turbines
I'm presuming you have a maximum head, if only from some practical limitations (height of the hill/house/tower etc.). Given that maximum you can select the turbine that best suits it, then use these guidelines
to calculate the minimum. If the scheme still works, you're done, if not you'll need to change something about the head, the flow rate or the turbine type and go back around the loop.
hope this helps
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