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Some help with college project about air battery?

  1. Jul 28, 2014 #1
    Hello everyone! I'm working on my practical project in college and it's roughly about ''air battery'' (CAES) which is filled with help of solar cell (eventually I need to build small version of it).
    My mentor explained it to me roughly as well and I would love some help as I'm not very good at thermodynamics.

    First thing that I'm not sure about is processes in model.
    They basically go like this:

    Compression of air
    Cooling compressed air
    Heating an air (later when we want to use it)
    Letting some of the air go to maintain same pressure in tank
    Expanding an air into turbine

    Does all that make sense?

    Let me know if you need me to go more in detail.. eventually I will, but this is just to check if my foundation is good or I'm missing something obvious.

    Thanks a lot!
  2. jcsd
  3. Jul 28, 2014 #2


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    Staff: Mentor

    Well, in terms of storing energy, why don't you just skip the cooling/heating and just used the compressed air itself as the source or energy. That is, fill a tank with compressed air and release it later on into a turbine to generate power.
  4. Jul 28, 2014 #3
    That's what I asked my mentor as well. He told me that we're cooling air because it would be two(or more)-stage compression. ..also, because it's storing energy (we're going to use it later) temperature would drop to room T anyway.
    Reason for heating it later would be to avoid temperature dropping below critical point (don't know what's critical point yet) during expansion itself.

    Does it still sound pointless or?
  5. Jul 28, 2014 #4


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    Staff: Mentor

    I guess for a school project it's fine. At first glance it looks like a sound project to me. I'd recommend posting the specifics of what you need help with. I don't think I will be able to personally help you, but I'm sure someone around here can.
  6. Jul 28, 2014 #5
    That's cool, thank you anyway!

    Well, if processes above makes sense, another thing that bugs me is how to calculate expansion from one to another tank.
    Basically, I would use two transformed extinguisher tanks. One would be main (used for storing compressed air), and the second one would be on side and used just for regulating pressure in first one during the air heating. Expansion into turbine is done from main tank only.

    So, i'm not sure how to calculate expansion (or how parametres would change by it) when there is two fixed volumes of tanks.

    Also, would that count as free expansion if air and presssure in second tank doesn't matter?

    And last but not least-does this calculation even matters if i'm just wacthing manometre and realising air with valve into another tank and nothing is changed in main tank except temperature.
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