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Alternator for Low Wind Speed Wind Turbine.

  1. May 12, 2008 #1
    Hi

    I've a wind turbine which have to run under a very low wind speed, from 2-3m/s.

    Currently, I'm using Envirotek V20, the result is around 1.5V-2.5V, and current is 0.3mA or nearly zero.

    My aim is to achieve 50W.

    Any suggestion for the alternator which I should use?
    p/s: without aided by any gear arrangement.

    thanks alot.
     
  2. jcsd
  3. May 12, 2008 #2

    russ_watters

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    Are you sure you have 50W of available wind energy at 2-3m/s? The alternator's size, unless it is absurdly large, doesn't affect the output power much.
     
  4. May 12, 2008 #3

    LURCH

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    Along with what Russ said; if the windspeed is that slow, I don't think any change of alternator is going to give you the Watage you're trying for. The only thing I can think o ffor increasing output is increasing input. Since you can't incrase the wind's speed, I suppose this will mean increasing the size of your airfoil blades. Catching more wind at the same speed will increase the energy that is being input into your system.
     
  5. May 13, 2008 #4
    think this is a good idea..

    I will try out with an experiment..

    thanks alot..
     
  6. May 13, 2008 #5

    russ_watters

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    What is the size of the turbine? We can help calculate the available energy and likely capture.
     
  7. May 13, 2008 #6
    I'm using this currently..
    www.envirotekpower.co.uk/V20info.html

    but I'm going to redesign the turbine blade..
    currently, I have few designs. they are most likely same as these examples
    www.peswiki.com/index.php/Image:Statoeolien_95x95.jpg
    www.peswiki.com/index.php/Image:Helix_Wind_95x95.jpg
    www.hi-energy.com.tw/selection-6-english.htm
    www.oregonwind.com/

    just not sure which can really function good in low wind speed, 2m/s-3m/s
    I think I have to run a few test on them..

    by the way, you are so kind, really thanks :)
    and I'm very appreciate..

    p/s: sry for the urls..
     
  8. May 14, 2008 #7
    Besides change the size of wind blades, Do you think it's possible to generate 50W with a gear system?

    my v20 now is able to achieve 165rpm @ 4.3m/s, and the current produce is almost 0! (even the wind speed reach 8m/s)

    do you think just because the alternator is a lousy one?

    many thanks:)
     
  9. May 14, 2008 #8

    russ_watters

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    More gearing will only hurt you - it doesn't amplify energy and you lose energy from friction.

    According to the site, that turbine only generates 3W (.25A @12V) at 4.5m/s using a turbine with a cross sectional area of .18 m^2. I don't have time to run through the energy calculation for the wind right now, but my gut tells me that if theirs can only generate 3W, you have no hope of generating 50W with a turbine that small.
     
  10. May 14, 2008 #9
    how about with only 2 gears, as to increase the rpm of alternator.

    wind turbine with a bigger gear, and small gear for alternator. So my alternator able to turn more round as wind turbine gear turns one round.

    or I can let alternators connected in series since my project can involves more than 1 wind turbine and alternator.

    thanks alot
     
  11. May 14, 2008 #10

    russ_watters

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    Well, you could certainly run 20 of them in parallel, or hook 20 up to a common alternator.

    But again, just changing the gear ratio does not change the energy you can generate. You'll increase the rpm, but decrease the torque.
     
  12. May 14, 2008 #11

    russ_watters

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    The wind energy available to one of those turbines, by the way, at 4.5 m/s is 8 watts. That's based on a kinetic energy calculation: 1/2 mv^2 = .5*(4.5*.18*1.29)*4.5^2 = 8. A total system efficiency of just under 40% is pretty good, so I wouldn't expect you to be able to beat their performance.

    1.29 kg/m^3 is the density of air.
     
  13. May 15, 2008 #12
    this fact is really disappoint me :(

    but how about increase the wind turbine size and with the help of gear ratio?

    thanks again
     
  14. May 15, 2008 #13
    I found this design is able to generate around 200 watts @ 10mph, 4.4704 m/s.

    unfortunately it is horizontal wind turbine.

    and it's able to generate 200W @ 4.4704 m/s, because it is horizontal?
     
  15. May 15, 2008 #14
    Dear Russ,

    I've found this, which is able to generate 150 Watts in a 10 mph wind!!

    Wow!!
     
  16. May 15, 2008 #15
  17. May 15, 2008 #16

    russ_watters

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    That person think's he's found a revolutionary new way to capture wind, but he hasn't. His own tests should tell him that:
     
  18. May 15, 2008 #17

    russ_watters

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    Yes, the physical size of the turbine is the key factor in determining how much power it can generate.
     
  19. May 15, 2008 #18

    russ_watters

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    No, it generates more power because it is bigger.
     
  20. May 21, 2008 #19
    dear russ, could you recommend some alternators that are suitable for low wind speed?
    because I'm trying to find those can generate well current & voltage under low wind speed.

    because this is the first priority then turbine design and gear system.
     
  21. May 21, 2008 #20

    Redbelly98

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    Russ, is that 8 watt figure per square meter, or for the area of Mecha's particular turbine, or some other area?

    I agree that increasing power must come from using larger turbine blades.
     
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