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Homework Help: Joule kelvin liquefier

  1. Mar 10, 2006 #1
    We have a helium liquefier which takes compressed He gas at 14 K, liquefies a fraction alpha and rejects the rest at 14K and atmospheric pressure.
    I've got to the stage alpha = (Hf - Hi)/(Hf - Hl)
    where Hf, Hi, Hl are the final, initial and liquid enthalpies respectively. I know that the liquid and the final enthalpies are determined, and that we have to find the smallest possible Hi to maximise alpha.
    The only problem is determining what Hl should logically be. All we know that it must be in equilibrium with the vapour in the liquefier. Any hints would be greatly appreciated.

  2. jcsd
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