2013



Results 1 to 11 of 11
  1. #1
    Join Date
    Nov 2008
    Location
    iraq
    Age
    35
    Posts
    2
    Rep Power
    0

    How can calculate ton of refrigeration in any units?


    Hi every one i'm new here ,
    i need help,
    How can calculate ton of refrigeration in any units?
    i mean at 3 phase and single phase,
    and what it mean CFM for ton refrigeration?



  2. #2
    Join Date
    Mar 2005
    Location
    u.a.e
    Age
    58
    Posts
    140
    Rep Power
    10

    Re: How can calculate ton of refrigeration in any units?

    you can check a unit's capacity from its model number and manufacturers data sheet, some units can identify easily by model numbers, Such as Mitsubishi MU24NV means 24000 BTU'S-2TONS /MU18000NV means 18000 BTU'S-1.5TONS.
    One TON is equals 12000BTU'S, Also if it is in KW then you can take 3.5KW's(REF)equals one Ton.
    CFM means cubic feet per minute and it is used for air quantity delivered to the area by a unit, approximately 400 CFM per Ton is a standard figure.
    For more details please refer to a book such as Modern Air Conditionind and Refrigeration Handbook.
    Refrigeration Capacity is same for 3phase and 1phase units but voltage and Current are differant.
    Last edited by malik55; 02-12-2008 at 08:34 PM.

  3. #3
    Join Date
    Aug 2005
    Location
    USA
    Posts
    5,340
    Rep Power
    16

    Re: How can calculate ton of refrigeration in any units?

    Welcome to the RE forums Azhar.

    I am at a loss to answer your question about refrigeration cooling capacity (Tons) for either 3 phase or single phase. They have no direct comparison. The electrical phase does not matter, only the operating conditions (evaporating and condensing temperatures).

    The phrase "CFM per Ton of Refrigeration" means this: To produce a Ton of Refrigeration (again at some operating conditions) the compressor has to compress "x" CFM of refrigerant. This relates to the volume of refrigerant vapor (in cubic feet per minute) on the suction side of the compressor to produce 1 Ton of cooling.
    If all else fails, ask for help.


  4. #4
    Join Date
    Nov 2008
    Location
    alaska
    Age
    48
    Posts
    11
    Rep Power
    0

    Re: How can calculate ton of refrigeration in any units?

    Guys:

    Cfm is only relative to compressor displacement, the COP has to be factored in. An example a booster has a large swept volume for low tonnage as compared to a high stage compressor or swing duty. Getting a copy of a good compressor selection program (mycom is easy to use and provides a lot of data on a calculated performance and then extrapolating by finding an approximate swept volume match at your operating conditions will be pretty close as efficiencies on compressors are fairly uniform.

  5. #5
    Join Date
    Aug 2005
    Location
    USA
    Posts
    5,340
    Rep Power
    16

    Re: How can calculate ton of refrigeration in any units?

    Quote Originally Posted by dglaab
    Cfm is only relative to compressor displacement...
    Well, there are several ways to talk about this. CFM is CFM. So if the context is displacement of compressors then you have compressor displacement X volumetric efficiency = ACFM. ACFM is the swept volume of gas the compressor moves in operation. The "A" in ACFM stands for "actual".

    So when you break this down into what it means, this is what you have:

    ACFM = the gas moved by the compressor
    CFM = compressor displacement
    CFM/Ton = volume flow of refrigerant gas required at the operating conditions to produce 1 Ton of cooling.

    If you know the compresor capacity then if you multiply CFM/Ton X Tons capacity of the compressor you find the total volume of gas moved by the compressor.

    Then, if you know the total volume flow of gas moved by the compressor you can do this:

    Compressor displacement (CFM) divided by the total volume flow (CFM) = volumetric efficiency.
    If all else fails, ask for help.


  6. #6
    Join Date
    Apr 2009
    Location
    Johannesburg
    Age
    60
    Posts
    1
    Rep Power
    0

    Re: How can calculate ton of refrigeration in any units?

    1 ton of refrigeration = 12000 btu's / hr
    1 ton of refrigeration = 3.51 kw cooling
    ( 12000 / 3414 = 3,51 )
    typically for 1 ton of cooling your air supply from the evaparator would be 400 cfm as a general guide.

    As a general guideline for sizing a/c units for small offices or bedrooms etc we use as quick guide 500 btu's/hr per sq meter or 11 sq feet.
    i.e A room measuring 4m x 3m = 12 sq meters
    Therefore a quick rule of thumb says we need a unit with a cooling capacity of 12 x 500 = 6000 btu's/hr,
    most manufacturers smallest unit would be 9000 btu's / hr so we would quote to install a 9000 btu' hr machine.

  7. #7
    Join Date
    Oct 2008
    Location
    Colombia
    Posts
    81
    Rep Power
    7

    Wink Re: How can calculate ton of refrigeration in any units?

    Quote Originally Posted by Azhar View Post
    Hi every one i'm new here ,
    i need help,
    How can calculate ton of refrigeration in any units?
    i mean at 3 phase and single phase,
    and what it mean CFM for ton refrigeration?
    Go to this link and take the ebook there. You can find all several equivalences between cfm and t.r. in ac and refrigeration.

  8. #8
    Join Date
    Apr 2009
    Location
    Panacea, Florida
    Age
    77
    Posts
    76
    Rep Power
    6

    Re: How can calculate ton of refrigeration in any units?

    Quote Originally Posted by Azhar View Post
    Hi every one i'm new here ,
    i need help,
    How can calculate ton of refrigeration in any units?
    i mean at 3 phase and single phase,
    and what it mean CFM for ton refrigeration?
    All of the major manufacturers - Carrier, Trane, York, Addison, and on and on - publish their catalogs for free download from the internet. Just google the name of a manufacturer, go to the website, and browse their product line. You will find performance data with total and sensible cooling capacity as a function of evaporator entering dry bulb and wet bulb, evaporator air flow, and condenser water or air temperature. Attached is a typical performance table for an air cooled five ton heat pump. (I accidentally uploaded it twice, only the 56MB file is readable.)
    Attached Files Attached Files

  9. #9
    Join Date
    Oct 2009
    Location
    India
    Posts
    3
    Rep Power
    0

    Re: How can calculate ton of refrigeration in any units?

    If got a coupel of cold & freezer rooms to install and i neet to work out wat size compressor and evaporator to use how do i work it out.
    room size 4m x 6m (4 Nos)
    meet, veg.

  10. #10
    Join Date
    Aug 2001
    Location
    Gold Coast, Australia
    Posts
    588
    Rep Power
    18

    Re: How can calculate ton of refrigeration in any units?

    Work out all your heat gains (sensible & latent), add your product heat load. Decide how fast you need the product to be brought from whatever temp. it is on entering the room to your desired temp.
    Using this information you can calculate the required RE (Refrigerating Effect). Then find your THR (Total Heat of Rejection). Decide what ambient you're assuming for the purposes of your design.
    IIrc, at this point you have enough information to select the major equipment.

    Then you need to do your pipe sizing, valve selection, other controls (EPR, CPR for e.g.) etc.

    Once you're happy with that lot, you're ready to figure out how you're going to build the cold room.
    Last edited by FreezerGeezer; 08-10-2009 at 02:18 PM.

  11. #11
    Join Date
    Mar 2008
    Location
    England
    Posts
    188
    Rep Power
    9

    Re: How can calculate ton of refrigeration in any units?

    You do need to provide a lot more information if you need help.
    Detail of the product type, plus entering temperature and final design storage temperature, amount of time to reduce the product to the design temperature.
    Insulation value of the store, design ambient temperature, lighting loads, number and type of occupants (people working in the store) other loads, fork lift trucks etc.

Similar Threads

  1. advanced refrigeration technology
    By Lc_shi in forum Fundamentals
    Replies: 10
    Last Post: 16-02-2011, 06:22 PM
  2. Replies: 9
    Last Post: 30-11-2009, 11:08 AM
  3. New Building, New Units!!!
    By Fett in forum Air Conditioning
    Replies: 6
    Last Post: 19-11-2008, 04:43 PM
  4. Portable Refrigeration Air Conditioner Units
    By possum in forum Fundamentals
    Replies: 2
    Last Post: 23-07-2007, 02:47 PM
  5. Rebuilt truck refrigeration units (Carrier)
    By Tuong in forum Fundamentals
    Replies: 0
    Last Post: 17-03-2003, 11:00 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
  •