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Joule Thomson

  1. Jan 21, 2009 #1
    I've been scouring the web in search of a Joule Thomson coefficient value for methane, but so far no luck.

    I have the volume, temperature, and specific heat as well... so I could also use the coefficient of thermal expansion for methane.. but I can't find that anywhere either!!

    Does anyone know of a good online reference?

    Thanka alot.
  2. jcsd
  3. Jan 22, 2009 #2
  4. Jan 22, 2009 #3
    For future reference, I did figure out that you can calculate the Joule-Thomson coefficient using Van der Waals constants.

    Another option uses Beattie-Bridgeman constants.

    So I was able to figure it out from those known values.
  5. Jan 27, 2009 #4
  6. Jan 27, 2009 #5
    Thanks for the reply, but I can't see how to find the Joule-Thomson coefficient.
  7. Jan 28, 2009 #6
    1. You open the page: Thermophysical Properties of Fluid Systems.
    2. On this page you select Methane instead of Water, select needed for you units of measurement, and select the form of database, for example, Isothermal. Then you press to continue.
    3.On the page Isothermal Properties for Methane you select temperature, for example, 300; select minimal, maximal pressure and increment, for example: 0 2 0.01
    Do not forget to clean the box N3 with Java
    4. Press for data
    5. On the next page you will see a table with many properties, including JTC
    6. To change the form and ranges of data you return back.

    I wish you good luck
  8. Jan 28, 2009 #7
    Thank you!

    Nice to know about this tool, very useful,

    I used:


    Equation (14)

    My results are slightly different, but the process in question is not isothermal, isobaric, or isochoric, the constant is enthalpy since it is effectively a throttling process.

    I'm not sure how to apply this to the tool you posted, but it is definately very cool. Thanks.
  9. Jan 29, 2009 #8
    The Equation (14 ) follows from the van der Waals equation, that is good for overall picture, but is not precise in details. The Joule-Thomson coefficient is very sensitive to parameters of the intermolecular forces. Therefore, it is better to use direct experimental data, generalized in databases, like the NIST Database.
  10. Apr 6, 2010 #9
    I've found in my book the J-T coefficient of Methane to be 4.38 K/MPa
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