Results 1 to 3 of 3
  1. #1
    Join Date
    Mar 2016
    Location
    Lithuania
    Posts
    2
    Rep Power
    0

    Discharge pressure lower limit



    I would like to ask several questions about R404A refrigeration system:

    1.What is the smallest allowable discharge pressure for this type of systems?
    2.Does expansion valves have minimum working pressure?
    3. Is it normal that suction pressure is about 2bar (-30oC saturated temperature) when cooling is needed to maintain +7oC temperature.

    Sincerely,
    Mantas K.



  2. #2
    Join Date
    May 2007
    Location
    Auckland
    Age
    67
    Posts
    3,362
    Rep Power
    31

    Re: Discharge pressure lower limit

    hello,
    Question /1 what ever SDT your select to operate must be reasonably constant, the specific weight of 404a requires pressure to push it around.

    Question /2 TXV are selected with a specific pressure drop range to supply evaporator with sufficient refrigerant to do cooling load.

    Question 3/ NO , YOUR EVAPORATOR is starved of liquid, due to most likely low discharge pressure. The evaporator super heat will be off the scale same with compressor suction super heat. The compressor will die shortly.
    So condenser fan control or a head master controller for low ambients, to get a system balance happening.
    magoo

  3. #3
    Join Date
    Sep 2007
    Location
    Somerset
    Age
    63
    Posts
    4,504
    Rep Power
    38

    Re: Discharge pressure lower limit

    A good question Mankam.
    And a brilliant and concise set of answers Magoo.

    Gas flow, density and Discharge Pressure have a huge effect, yet many overlook them when fault diagnosing.
    Grizzly
    Despite the High Cost of Living it still remains Popular!

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
  •