Forums: Skydiving: Wind Tunnels:
Energy Concious Wind Tunnel?

 


kiittycatt  (C 36134)

Sep 14, 2005, 8:15 AM
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Energy Concious Wind Tunnel? Can't Post

Does anyone know if there currently exists in any wind tunnel a means of recycling the energy from the exhausted wind? I.E. wind turbines at top powered by the exhausting air?


rehmwa  (D 12816)

Sep 14, 2005, 9:27 AM
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Re: [kiittycatt] Energy Concious Wind Tunnel? [In reply to] Can't Post

You think that any energy you get out would be more than the additional load this would create?

I don't. Better to just stick a fan in a windy region of the country.


kiittycatt  (C 36134)

Sep 14, 2005, 9:44 AM
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Re: [rehmwa] Energy Concious Wind Tunnel? [In reply to] Can't Post

It wouldn't recover all the energy used to generate the wind, however it would certainly recover some of it and would save the operators money for sure. I don't have any specifics yet, but was thinking of doing a research project on it, and was just wondering if anything like it already existed.


Paulipod  (B 1234)

Sep 14, 2005, 10:34 AM
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Re: [kiittycatt] Energy Concious Wind Tunnel? [In reply to] Can't Post

Not so sure that this is something that is so feasibleWink

Basically adding any kind of impedance to the output flow in most facilities would increase load on the motors and therefore cost more in energy.

It is the same for each flyer you put in the wind.... each additional load adds work for the drive.

Takes more energy to create drive than you can harness from it - ie conversion losses etc

Damn - and I was on track for creating a perpetual motion machineTongueLaugh


rehmwa  (D 12816)

Sep 14, 2005, 11:22 AM
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Re: [kiittycatt] Energy Concious Wind Tunnel? [In reply to] Can't Post

In reply to:
and would save the operators money for sure.

Not what I mean. What you are proposing is the same as saying hooking up a generator light to your bicycle tire won't make you pedal harder.

I don't think you'd recover any of the energy you are speaking to. What you would do is to create a larger draw on the tunnel than without a device. Then the device would recover a portion of that extra loss.

made up example - If a tunnel would use 100 units of energy. This device would increase that to 110 and you'd recover 5 to sell back. Thus you now use 105 whereas before you only used 100 (that type of thought). If you are thinking in terms of an energy/mass balance - remember to draw your control lines to contain both the tunnel system AND the recovery system - then treat as steady state, do the balances, etc.....

Stupid laws of thermodynamics.....

Maybe Kallend could explain more clearly.


(This post was edited by rehmwa on Sep 14, 2005, 11:22 AM)


alw  (C 35179)

Sep 14, 2005, 12:55 PM
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Re: [kiittycatt] Energy Concious Wind Tunnel? [In reply to] Can't Post

Don't go there Shocked

There is a component of work that lifts the people in the tunnel
There is a component of work that moves the air through the tunnel
There is a component of work that overcomes the resistence to the air moving through the tunnel

What's energy is left in the air after it leaves the tunnel is available for conversion to some other form of energy. That prossess would be lossy.

The cost benefit of capturing that energy would be an interesting equation, but knowing what wind energy costs to produce I would say it would cost more to recature it.

NOW, Crazy if you made the air path a closed loop (recirculated) your fans would be more efficient and that would be an interesting equation as well. I'm sure that it has been calculated. As long as tunnel flyers are willing to pay the energy loss costs of open circuit tunnels, my guess is that no greenies are going to build closed circuits for the purposes of saving energy.



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