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Scroll compressor modeling

  1. Jul 31, 2015 #1

    I am currently trying to model a water-cooled scroll compressor but do not have enough data to predict output conditions.

    At the moment, I can collect inlet and discharge pressure, outlet temperature, water mass flow rate as well as inlet and outlet temperature.

    I would like to be able to predict outlet conditions, (Pdischarge and T2) knowing the input power to the compressor experimentally since it takes quite a lot of information to model it geometrically.


  2. jcsd
  3. Aug 1, 2015 #2


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    Collect throughput mass flow and inlet temperature as well . Then it's just simple sums .
  4. Aug 1, 2015 #3
    Thanks for your reply. However, I have not been able to do that at least for now. That's why I'm looking for an alternative.
  5. Aug 1, 2015 #4


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    Without knowing the air (?) mass flow there is no way of doing a proper energy balance .

    I'm sure that there is a way of finding this mass flow - after all it is constant anywhere in the system from first inlet to final discharge .

    Any way of fitting a flow meter to inlet or discharge ??
  6. Aug 1, 2015 #5
    It's a cryogenic cooling unit for nitrogen liquefaction using helium as the refrigerant. I hope to later on back calculated the Helium mass flow rate knowing the amount of nitrogen liquefied but still that wouldn't be accurate. At the moment I can't fit a mass flow meter unfortunately!
  7. Aug 7, 2015 #6


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    Hi Ariel, welcome to the board,
    A screw machine is a positive displacement type of compressor but it will have considerable slip during operation so mass flow drops as discharge pressure increases. The manufacturer should be able to give you discharge pressure and temperature along with flow rate for any condition. You'll need to know what that is before you can try and model it because the slip will vary depending on pressure differential and could be quite large.

    Can you get mass flow from the manufacturer, and if you can, why do you need to create your own model?
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