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Compressed air as fuel

  1. Jul 25, 2007 #1
    hey guys can any1 tell me wats the concept behind cars using compreesed air as fuel....
     
  2. jcsd
  3. Jul 25, 2007 #2

    russ_watters

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    It is basically just a storage medium. You get power from the power grid, run a compressor to fill a tank of air, then release that air through a turbine to power whatever you need to power.
     
  4. Jul 25, 2007 #3

    mgb_phys

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    The main practical problem is the weight of the tanks needed to hold the high pressure air.
    It was used for small 'steam' engines running in places like wood pulp mills where they couldn't use steam because of the risk of fire. The advantage of compressed air is that you don't need to modify the rest of the steam engine.
     
  5. Jul 28, 2007 #4
    hi

    ya dats fine but can u tel me something about the which i can get from compressed air...
     
  6. Jul 28, 2007 #5
    please write in a proper way, its hard to understand what you are saying
     
  7. Jul 28, 2007 #6

    russ_watters

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    You'll need to speak in correct English so we can understand what you are asking.
     
  8. Jul 28, 2007 #7

    mgb_phys

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    I'm assuming from your name that English isn't your first langauge (and you aren't just using txt-speak to be kewl).

    There are 3 simple ways to power at least a toy car with compressed air:

    1, You can just blow air out of the back and use the reaction force. Just imagine filling a balloon and letting go! You can also demonstrate this with an office chair and a CO2 fire extinguisher if no one in the office is watching.

    2, You can use the expanding air to drive a piston, just like a steam engine, there used to be a popular toy car which did this. Just look up the details of how any steam engine works and substitute compressed air for high pressure steam.
    This is the easiest to build for a school project.

    3, You can use the air pressure to drive a turbine and then either use the turbine directly to drive the wheels or run a genarator to create electricity and then use electric motors to drive the wheels. Again this is exactly the same principle as a steam turbine.
     
  9. Jul 29, 2007 #8
    run a reciprocating compressor with input and output swapped, see what you get.
     
  10. Jul 29, 2007 #9
    I think compressed air engines are definitely worth looking into. I'm surprised nobody has mentioned http://home.ctlnet.com/~robotguy67/classic_cars/air_engines/V-Twin/air_engines.htm
    It's got 2 pretty good designs: too bad the plans haven't been made available yet.

    Of course, as in the Toyota Prius conundrum, just because something is better for the environment in its consumer use doesn't mean the processes required to maintain it don't have a bad impact on the environment. I mean the electricity to compress the air to put in the air tank must come from somewhere.

    If you think about alternative energy sources, you could have a wind farm make electricity from air movement which then compresses the air into a tank, which is then released into chambers which rotate a shaft and drive something, so it's like converting moving air to movement, although in an indirect manner.
     
  11. Jul 29, 2007 #10

    mgb_phys

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    This is done, although generally they use hydraulic oil pumps.
    It has the advantage that most the working parts are at ground level instead of on the top of a tower and you can combine the outputs of several windmills into one power source.

    ps - I would love one of those rotary engines!
     
    Last edited: Jul 30, 2007
  12. Jul 30, 2007 #11
    That makes a lot of sense. I agree, the rotary engine is awesome, especially with the narrow form factor. Also, being able to start in any position is a plus.
     
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