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Forum Index : Other Stuff : micro-hydro from air
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| jmccull Newbie  Joined: 31/10/2014 Location: United StatesPosts: 7 |
I'm working on using compressed air to spin two pelton turbines simultaneously. A 12vdc air compressor rated at 3.71 cfm @ 90 psi is equal to water at 27.75 gpm and 207' head. If one is 12vdc, it can charge batteries for 12vdc compressor while other turbine can be at desired voltage for an inverter. 12vdc, 24vdc, 36vdc, 48vdc My compressor has an air pressure switch, so that it can turn off and on according to pressure in the tanks. This way turbines continue to charge while compressor is off. Any questions? comments? |
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Gizmo Admin Group  Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
Whoah! How did you work that out? I can tell you, without even doing the maths, thats like saying a 2 year old child has as much strength as Arnold Schwarzenegger! Glenn The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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| jmccull Newbie Joined: 31/10/2014 Location: United StatesPosts: 7 |
1 psi = 2.3' of drop so 90 psi x 2.3 = 207' of drop. 1 cfm = 7.48 gpm so 3.71 cfm x 7.48 gpm = 27.75 gpm The compressor is not turning the turbine, it is maintaining the air pressure in the tanks which is released through a small nozzle onto the pelton wheel. A single psi is one pound of pressure or force on one square inch. Doesn't matter if air or water, still one pound of force. |
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| jmccull Newbie Joined: 31/10/2014 Location: United StatesPosts: 7 |
At the moment, I'm planning to power only my compressor from a single 12 vdc battery that is charged by my 63 amp 12 vdc chevy alternator. My compressor only draws 15 amps, so even an inefficient car alternator should be fine. I'm curious to see if i can get enough power from lower air pressures, to keep my battery charged. If I can release air at 40 psi instead of 90 psi, then my compressor will run less but my alternator will still be storing energy in my battery. I may decide to add an inverter and another battery later on this 12 vdc side. More interested in adding a turbine set at a higher voltage to charge a battery pack for a large inverter. |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
No, 27.75 gpm of air has much less energy than 27.75 gpm of water. And a pelton wheel is designed to work with a non-compressible liquid, like water. For air you would get better results using a turbine or air engine. But more importantly, your trying to build a device that powers itself. Not going to work, despite all the fake YouTube videos. The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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Tinker Guru  Joined: 07/11/2007 Location: AustraliaPosts: 1904 |
What our newbie seems to forget is that water is about 800 times denser than air. So, its not just a pressure or gpm equation. Anyway, I'm not discouraging you to find that out for yourself. You'll have fun experimenting and the lessons learned will be much better grasped than anything other forum members try to convince you of. Klaus |
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| jmccull Newbie Joined: 31/10/2014 Location: United StatesPosts: 7 |
The 27.75 gpm from the compressor is being used to fill an air tank. Which is then released at a suitable pressure to spin the turbines. You're confusing pressure with volume. A pound of pressure is still a pound. Getting something for nothing would be expecting my compressor to charge a dead battery. |
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| jmccull Newbie Joined: 31/10/2014 Location: United StatesPosts: 7 |
Yes water is a lot more dense than air, which is why i have to compress it, in order to achieve the higher pressure. 90 pounds of pressure focussed on one square inch is still 90 pounds whether it's water or COMPRESSED air. Windmills don't use compressed air. |
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| Gizmo Admin Group Joined: 05/06/2004 Location: AustraliaPosts: 5078 |
I'm am too tired to give an intelligent answer. And I dont like banging my head against a wall. Build your device. The advice I can give is it wont work, because you have a misunderstanding of several engineering principles and physics. To save yourself wasted time and money, do your research first and if you can, go talk to a physics teacher/engineer. The best time to plant a tree was twenty years ago, the second best time is right now. JAQ |
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