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  1. #1
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    Question about air-conditioning DX evaporator



    Hi friends,

    For a DX evaporator for air-conditioning system, Do anyone have a simple documents that shows :

    What is evaporator temperature standard ?
    What is air temp passing form evaporator ?
    What is air return temperature to evaporator ?

    I think evaporator temp. must be 5.5C ~ 7.2C , Air passing form evaporator coil should be something about 17 ~ 18 C and air returning to system must be 27~28C. Maybe these temperatures are not correct exactly. I want a documents that shows these temperatures standard clearly, I searched internet but didnít find suitable document and also I didnít find it at Ashrea.

    Thanks for your help in advance.

    Sincerely yours.



  2. #2
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    Brian_UK is offline Moderator I am starting to push the Mods: of RE Site Moderator : and general nice guy
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    Re: Question about air-conditioning DX evaporator

    It is difficult to say what the evaporator temperature should be when the design space temperature is so variable.

    Every space is different.
    Brian - Newton Abbot, Devon, UK
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  3. #3
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    Re: Question about air-conditioning DX evaporator

    Quote Originally Posted by Brian_UK View Post
    It is difficult to say what the evaporator temperature should be when the design space temperature is so variable.

    Every space is different.
    Dear Brian_UK,

    Thanks for your reply. I can understand your mean clearly, But I think there should be a standard in this case.

    For example regarding water chillers for air-conditioning system, We suppose water temperature that leaves evaporator to fan-coils 45 F and water temperature that comes back to evaporator of chiller 55 F.

    As you told it would be different in situations and cities as result of condition or system design but I think we should have a standard.

    When you see most of rotary compressors, Catalogue mentions nominal capacity of rotary compressor at Te = 7.2 C , Or for example when you check capacity of expansion valves of Danfoss the nominal capacity on catalogue is at Te = 5.5 C.

    (Te = Evaporator temperature)

    I do not have any source on my hand but I think on air-conditioning system we should suppose Te temperature 5.5 ~ 7.2 C.

    Sincerely yours.

  4. #4
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    Re: Question about air-conditioning DX evaporator

    Dear Friends,

    I found my reply by own and i want to put reply to this topic for others use, How can i attach a PDF document here ?

    If anyone thinks that this document could be useful let me know how can i attach this here.

    Sincerely yours.

  5. #5
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    Re: Question about air-conditioning DX evaporator

    Quote Originally Posted by A.Mortezania View Post
    Dear Brian_UK,

    Thanks for your reply. I can understand your mean clearly, But I think there should be a standard in this case.

    For example regarding water chillers for air-conditioning system, We suppose water temperature that leaves evaporator to fan-coils 45 F and water temperature that comes back to evaporator of chiller 55 F.

    As you told it would be different in situations and cities as result of condition or system design but I think we should have a standard.

    When you see most of rotary compressors, Catalogue mentions nominal capacity of rotary compressor at Te = 7.2 C , Or for example when you check capacity of expansion valves of Danfoss the nominal capacity on catalogue is at Te = 5.5 C.

    (Te = Evaporator temperature)

    I do not have any source on my hand but I think on air-conditioning system we should suppose Te temperature 5.5 ~ 7.2 C.

    Sincerely yours.
    There is no standard evaporating/condensing temperatures because it depends of system design (temperatures, relative humidities inlets/outlets). Usually evaporating temperature for air cooled finned evaporator is around 3C below suface temperature. Condensing temperature is above 3-7C above surface temperature.
    In datasheets compressors parameters are presented (mostly) according to ARI conditions.

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