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Cooling in high pressure

  1. Jan 13, 2006 #1
    ok, i have forgotten my thermodynamics, and need a confirmation for my thoughts here...

    if youd compress He gas by blowing more gas into a thermo-isolated tank, the tank would get hotter right?
    and after compressing it enough the gas will become fluid (thats not a real phase transition, but you cant call it gas nor liquid after some density).

    1) would you get a solid state after even more compression?
    -my guess is no, because i cant see anything that would cause such a phase transition, i dont think the attractive powers will ever get strong enough if we started with He gas at room temprature and 1atm, as the temprature keeps rising when we compress it.

    2) will there be a change of the temprature gradient as a function of pressure or will the temprature rise leniearly as a function of pressure?
    -my guess is it'll rise linearly, because the work done for increasing the pressure is always the same for constant volume, but youd get less molecules inside the tank per unit pressure increase.

    3) what would happen if youd compress it all enough to become "quark plasma" (like neutron star)?
    - my guess is that it'll be VERY hot, it should make an explosion when it collapses like stars do, and we'll probably wont see it anymore, because light doesnt interact with it anymore.

    am i right?
    please regard all three guesses....

    by the way, i kinda got carried away with this post, so the title is a bit misleading, no cooling here if im right... so if any moderator is there, feel free to change the subject's name...
    Last edited: Jan 14, 2006
  2. jcsd
  3. Jan 13, 2006 #2


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  4. Jan 14, 2006 #3
    thanks for the reply,
    so they dont know what happen's at low temprature and high pressure.
    but im not necessarily talking of low temprature, if my guesses are correct the system should be very hot...

    anyway, i ran into something interesting here:
    "This gas (He) has a negative Joule-Thomson coefficient at normal ambient temperatures, meaning it heats up when allowed to freely expand."

    does that mean that on expansion it gets heated, and on compression it gets cold? (untill the coefficient changes its sign)?
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