Results 1 to 4 of 4
  1. #1
    lemminger's Avatar
    lemminger Guest

    Lightbulb Gas velocity in vertical risers to ensure proper oil return



    Hi

    I'm about to size a vertical riser on a CO2 suction line. But I’m finding it very difficult to obtain some proper design guideline.

    If I look in my ASHRAE Handbook (2010 edition - the one with a CO2 chapter), they simply refer to riser sizing in the halocarbon section. The halocarbon section has a lot of tables for different refrigerants but none for CO2 (as far as I can see).

    So what method do you guys use to ensure proper annular flow in your CO2 risers?

    One method I’ve been thinking about trying, to use Bernoulli’s equation for pressure (and thereby force acting on a particle). But this doesn’t really apply to the annular flow profile.

    I've also been thinking about scaling one of the known tables from ASHRAE with the difference in density. But once again, density most relates to buoyancy and less to the friction forces driving the oil up the tube walls.

    Any ideas are much appreciated. I know that most of our design guidelines are made from good old experience and trial-and-error, but if you got any sources/documents to include i would be perfect.



  2. #2
    Join Date
    Aug 2010
    Location
    UK
    Posts
    110
    Rep Power
    14

    Re: Gas velocity in vertical risers to ensure proper oil return

    Are you sizing a transcritical or cascade system?

  3. #3
    Join Date
    Aug 2010
    Location
    UK
    Posts
    110
    Rep Power
    14

    Re: Gas velocity in vertical risers to ensure proper oil return

    The IIAR have a cascade Ammonia/CO2 book which includes a section on pipe sizing. You could also take a look on the BOC website.

  4. #4
    Join Date
    Mar 2009
    Location
    U.S.A.
    Posts
    320
    Rep Power
    20

    Re: Gas velocity in vertical risers to ensure proper oil return

    https://www.thermalfluidscentral.org...rainment_limit

    The Danish Research Institute
    The Industrial Refrigeration Consortium at the University of Wisconsin, Madison, Mr. Todd Jekyl

    The magic names for the math and the experimentation include:

    Wallis
    John c Chan
    Kutateladze
    Banerjee
    Surgenor
    And a host of others...The Russian work was the earliest definitive. The Web Address gives a flock of algebra derived from separate work by certain of these parties.

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •