Page 2 of 2 FirstFirst 12
Results 14 to 21 of 21
  1. #14
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    The vending machine and automotive systems that use CO2 are transcritical cycles, they don't actually condense the CO2 refrigerant.
    Liquid in any part of the cycle would be very very bad for the equipment.
    If more government is the answer, then it's a really stupid question.

  2. #15
    Join Date
    Jul 2000
    Location
    Guayaquil EC
    Posts
    10,328
    Quote Originally Posted by mark beiser View Post
    The vending machine and automotive systems that use CO2 are transcritical cycles, they don't actually condense the CO2 refrigerant.
    Liquid in any part of the cycle would be very very bad for the equipment.
    This is partly true, since in a transcritical cycle when the heat rejection is done, there is no condensing going on as would be the case in a subcritical system. This is why a transcritical "condenser" is called a gas cooler.

    There is a liquid phase present in the transcritical cycle but it occurs after the expansion device during expansion when the pressure drops below the critical point, creating a two phase flow to the evaporator where the liquid is boiled off. The CO2 refrigerant then enters the compressor slightly superheated.

    Here's a very good explanation from Danfoss:

    http://www.ra.danfoss.com/TechnicalI...0%28CO2%29.pdf

    This a video produced by Danfoss which shows CO2 phase changes and also gives a little historical background of CO2 refrigeration, which was first introduced way back in 1850 and peaked in the 1920s.

    http://video.google.com/videoplay?do...81612782948466

  3. #16
    Join Date
    Aug 2004
    Location
    North Richland Hills, Texas
    Posts
    14,914
    Quote Originally Posted by icemeister View Post
    Here's a very good explanation from Danfoss:

    http://www.ra.danfoss.com/TechnicalI...0%28CO2%29.pdf
    Thanks, that is just a little bit more informative than the 8 year old ACHR News article I was looking at.
    For a while I was sort of following how things were playing out in Europe with the vending and automotive CO2 stuff, but never really dug into the details of what is going on at each point in the cycle.

    Then I lost interest in it.
    If more government is the answer, then it's a really stupid question.

  4. #17
    Join Date
    Dec 2010
    Location
    Toronto
    Posts
    1,253
    Many of the fridgies in Europe complain about CO2 systems blowing up in supermarkets, pretty dangerous. Most of the mini-splits over there are CO2 as well as the govt is forcing the phaseout of anything with a high global warming potential.

    Most new domestic fridges are Propane also.

  5. #18
    Join Date
    Oct 2005
    Location
    B.C. Canada
    Posts
    855
    We got a few CO2 Supermarkets out this way, but from what I understand they are running a secondary refrigerant (glycol or whatever) would love to learn more about it.. Couple guys on here have some experience with these systems, there is even pictures.. i cant remember where.

  6. #19
    Join Date
    Sep 2008
    Location
    Western PA
    Posts
    25,567
    Quote Originally Posted by SolarMike View Post
    Many of the fridgies in Europe complain about CO2 systems blowing up in supermarkets, pretty dangerous. Most of the mini-splits over there are CO2 as well as the govt is forcing the phaseout of anything with a high global warming potential.

    Most new domestic fridges are Propane also.
    The reasons for those blowouts were bad joining procedures.


  7. #20
    Join Date
    Dec 2010
    Location
    Toronto
    Posts
    1,253
    Quote Originally Posted by jpsmith1cm View Post
    The reasons for those blowouts were bad joining procedures.

    Very true....

  8. #21
    Join Date
    Jul 2001
    Location
    Canada
    Posts
    1,810
    they are running a secondary refrigerant

    http://www.coldsystemsllc.com/co2-refrigeration.html

Page 2 of 2 FirstFirst 12

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
Comfortech Show Promo Image

Related Forums

Plumbing Talks | Contractor Magazine
Forums | Electrical Construction & Maintenance (EC&M) Magazine
Comfortech365 Virtual Event