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  • Generating power from air flow

    Discussion in 'The main mechanical design forum' started by nacimroc, Jul 8, 2016.

    1. nacimroc

      nacimroc Member

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      I am wondering if there is any way to charge a battery from an air flow in a pipe (pipe diameter no bigger than 20mm ish)? I have the choice of either a very low flow (0.5 litres/min) or charging from a compressed air supply. The compressed air method wouldn't be ideal.

      I would only need tiny amounts of power but the unit would be in a remote location with no power source.

      I am being slightly restrained as its for a product I am thinking of producing.

      Thanks
       
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    3. Dana

      Dana Well-Known Member

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      Certainly it can be done, but the power produced will be minimal at any reasonable airflow or pressure. What is producing the airflow in the first place?
       
    4. nacimroc

      nacimroc Member

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      It is landfill gas (The EX part I would worry about later, I am just curious if its feasible for now). If the landfill gas can't be used the possibility of a compressed air supply could be used. Are there any products out there already?
       
    5. Sekocan

      Sekocan Member

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      How will you supply compressed air without power? May be if you can give some more details, we can find a workaround.
       
    6. nacimroc

      nacimroc Member

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      There is a compressed air supply where I will install the unit but no power. I would like to tap into the compressed air line and use it to turn a mini generator to create power.
       
    7. Dana

      Dana Well-Known Member

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      0.5l/m (.0083 l/sec) is a very low flow; not much energy there. In a 20mm pipe that's an average velocity of 0.0265 m/s. Air is 1.23kg/m³ under standard conditions, so that's 0.00001025 kg/sec. This would yield (at theoretical 100% efficiency) 0.00000000359903125 watts. To put that in perspective, a single AA battery (1.5V, 2700mAH) stores 4.05WH of energy. That means your airflow would be able to fully charge the battery in... 1284 centuries.

      That's assuming nothing but the kinetic energy of the flowing air. If there's pressure behind it, that's a different story; you need to know the actual pressure drop across your device to compute the actual power... but if you're already getting only 0.5l/min in that 20mm pipe there can't be a significant amount of pressure available.
       

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