2013



Results 1 to 7 of 7
  1. #1
    Join Date
    Apr 2001
    Location
    UK
    Posts
    2,156
    Rep Power
    17

    How to Correctly Size Condensing Unit and Evaporator


    Ive worked out a cooling load for two Chiller rooms
    The first one , the duty required is 4.32 Kw
    The second is 6.29 Kw

    What is the correct way to to size the condensing unit and evaporator coil using the wholesalers charts.

    This has always been a grey area for me, and Im determined to get it right and learn the proper way to do it.

    The third question is, how to I accurately select the orifice for the expansion valve

    Thank you in advance


    Any opinions, statements and facts expressed in this message do not constitute legal advice in any shape or form and is given for a general outlook in nature. You are advised to seek appropriate and specific professional assistance from a regulated and authorised advisor for definitive advice.

  2. #2
    Join Date
    Oct 2003
    Location
    Belgium
    Age
    52
    Posts
    5,501
    Rep Power
    22

    Re: How to Correctly Size Condensing Unit and Evaporator

    What brand you're used to work with for the compressors and evaporators?
    Brand for the TEV?
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

  3. #3
    Join Date
    Aug 2004
    Location
    Holland
    Posts
    55
    Rep Power
    11

    Re: How to Correctly Size Condensing Unit and Evaporator

    For the evaporator the first question is what kind of thing are stored.
    IE for unpakked meat you need a high relative humidity.
    For other things a low as possible relative humidity.
    For high relative hunidity you wil need a evaporator witch wil have high overheat and "high" evaporator temperature.
    So you must select a bigger evaporator with bigger airflow.
    on low humidities a smaller evaporator is selected to obtain lower evaporator temperatures with lower airflow.

    For the compressor condensing unit rule of thumb select the desired operating evaporator pressure select the next bigger size close to what you need in total heat displacement.

    Selecting a orifice is simple.
    You now the total capacity, the desired range of evaporating pressure, check the orifice selecting chart op the expansionvalve manufacturer.
    If you use danfoss, the selectingchart is printed on the inside of the box.

    Victor

  4. #4
    Join Date
    Apr 2001
    Location
    UK
    Posts
    2,156
    Rep Power
    17

    Re: How to Correctly Size Condensing Unit and Evaporator

    Quote Originally Posted by Peter_1
    What brand you're used to work with for the compressors and evaporators?
    Brand for the TEV?
    Hello Peter,

    Condensing Unit are always Le Unite Hermetique
    Expansion Valves danfoss
    evaporators Friga Bohn

    Product is cake mix..............in liquid form, contains flour and egg , other ingredients.........I think am looking to maintain temp of around 2Celcius in room
    Any opinions, statements and facts expressed in this message do not constitute legal advice in any shape or form and is given for a general outlook in nature. You are advised to seek appropriate and specific professional assistance from a regulated and authorised advisor for definitive advice.

  5. #5
    Join Date
    Oct 2003
    Location
    Belgium
    Age
    52
    Posts
    5,501
    Rep Power
    22

    Re: How to Correctly Size Condensing Unit and Evaporator

    I suppose you calculated the needed capacity.

    A FHS4531 ZHR gives 4,8 kW at -7C evaporating and ambient 32C, connected to an SD062R with orifice 3 in a TES2.

    A FHS4540 ZHR gives 6,08 kW at -7C evaporating and ambient 32C, connected to an SD082R with orifice 4 in a TES2.

    Did the calculation for UH with their selection software, the evaporators via the catalogs I have here and the Danfoss selection also with the catalog. Danfoss also has a small software program for this.

    You said you wants to maintain 2C, so assume +/- 7 to 10 K DT so evaporating at -5C to -7C. Max ambient = 32C.

    We discussed this also in the past in another thread: you can make 100 calculations but will never find a condensing unit that precisely matches the evaporator and vice versa. And the given capacities are only valid as long load in the room remains the same, the ambient remains the same, the humidity doesn't change too much...in fact all parameters which changes continuous without the possibility to counteract these.

    For the above proposal, it took some minutes to make the calculation. It's not worth to calculate it realy much deeper then I did, at least... that's my opinion.
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

  6. #6
    Join Date
    Apr 2001
    Location
    UK
    Posts
    2,156
    Rep Power
    17

    Re: How to Correctly Size Condensing Unit and Evaporator

    Thx Peter.. I appreciate yur help.
    I shall cross reference, and yes I think I get the hang of it.
    Any opinions, statements and facts expressed in this message do not constitute legal advice in any shape or form and is given for a general outlook in nature. You are advised to seek appropriate and specific professional assistance from a regulated and authorised advisor for definitive advice.

  7. #7
    Join Date
    Dec 2002
    Location
    Malaysia
    Age
    49
    Posts
    86
    Rep Power
    12

    Re: How to Correctly Size Condensing Unit and Evaporator

    My suggestion ( maybe common sense !) is always to get the load right to the best estimate - then do as Coolman suggests then do as Peter as put forward.....should be fine !

Similar Threads

  1. Daikin a/c units.
    By rick in forum Air Conditioning
    Replies: 59
    Last Post: 18-02-2008, 10:22 PM
  2. Need a correctly sized valve
    By Abe in forum Commercial
    Replies: 2
    Last Post: 26-10-2005, 08:42 PM
  3. Evaporator Concerns-Use of a 30 TOR Unit for a 40 TOR System
    By nrps in forum Technical Speculations
    Replies: 9
    Last Post: 05-07-2004, 11:47 AM
  4. Selecting Evaporator coil and condensing unit
    By Abe in forum Tools and Calculators
    Replies: 7
    Last Post: 04-04-2003, 03:20 PM
  5. Matching Evaporator with Condensing Unit
    By Abe in forum Technical Discussions
    Replies: 12
    Last Post: 25-07-2001, 08:57 AM

Posting Permissions

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