2013



Results 1 to 9 of 9
  1. #1
    Join Date
    Jan 2005
    Location
    usa
    Age
    57
    Posts
    7
    Rep Power
    0

    Question Horsepower to tons/ref. conversion ?


    We have a cascade system with a 15 hp low stage compressor and a 30 hp high stage compressor. Is there an easy way to figure the tons of refrigeration this system is putting out? The high stage has a tower water cooled condenser. Low stage is 508B and high stage is 22.



  2. #2
    Join Date
    Sep 2003
    Location
    ISRAEL
    Age
    62
    Posts
    3,621
    Rep Power
    23

    Re: Horsepower to tons/ref. conversion ?

    Hi Hank,

    It depend on evaporating and condensing temp of the compressor.

    Wouldn't it be easy to to look in the compressor manufacturer catalogue and choos it from there?

    Chemi

  3. #3
    Join Date
    Jan 2005
    Location
    usa
    Age
    57
    Posts
    7
    Rep Power
    0

    Re: Horsepower to tons/ref. conversion ?

    Actually we were wondering what affect the cascade aspect has on the tonage rating? An older similar unit at this site has 4 30 hp compressors, and another has 2 50hp compressors, while our cascade systems do the same with a 15hp and a 30 hp, it appears that the cascade exponentially increases the capacity. It is hard to grasp how this can be possible, but it is, it works.

    Our evap temp is -80C and our cond. temp is -10C for the low stage and the high stage is -10C for evap and +20 to +35C condensing temp.

  4. #4
    Join Date
    Mar 2005
    Location
    USA
    Age
    67
    Posts
    641
    Rep Power
    10

    Re: Horsepower to tons/ref. conversion ?

    I do not know of any way to convert input power (HP) into tons of capacity. There are too many variables, such as evaporating temps, condensing temps, stages of economizing, type of refrigerant used and so on.

    Like suggested above, use the compressor manufacturers data and your actual operating conditions.

    The 30 HP compressors may not be drawing 30 HP, but may actually be drawing 23 or 24 HP. The 50 HP compressors may be drawing 45 HP. So you can not compare motor size to get an accurate comparison.

    Ken

  5. #5
    Join Date
    Mar 2010
    Location
    kuwait
    Age
    38
    Posts
    1
    Rep Power
    0

    Question Re: Horsepower to tons/ref. conversion ?

    can i use r134 compressor in r12 system ?

  6. #6
    Join Date
    Mar 2009
    Location
    U.S.A.
    Posts
    248
    Rep Power
    7

    Re: Horsepower to tons/ref. conversion ?

    Well if the Condensing for the low temp cmp is the same as the evap for the high stage, its not cascading; or it has an infinitely large interstage heat exchanger.

    Nominally: in the absence of closed cycle injection or other enhancers to the low side circuit or direct heat rejection from the low stage compressor, the heat absorbed (the refrigeration effect) plus the heat input of the low stage compressor (thermal equivalent of the BHP draw, not the nameplate HP) will represent the high stage load. Identify the numbers for the High Stage compressor at the specific evaporating and condensing temperature; measure the current input to the Low Stage compressor; deduct one from the other and you should end up with the low stage capacity.

  7. #7
    Join Date
    Nov 2004
    Location
    China
    Posts
    176
    Rep Power
    10

    Re: Horsepower to tons/ref. conversion ?

    Measure the process flow and temperature change. If you can find the specific heat of the process fluid it's easy to calculate the refrigeration effect (capacity). Measure the motor amps to calculate the power input. Divide one by the other & you have COP

  8. #8
    Join Date
    May 2010
    Location
    KSA
    Age
    38
    Posts
    5
    Rep Power
    0

    Re: Horsepower to tons/ref. conversion ?

    Dear all the formula is
    1.34hp = 3412 Btu/hr
    with regards:

  9. #9
    Join Date
    Jul 2009
    Location
    Illinois
    Posts
    189
    Rep Power
    6

    Re: Horsepower to tons/ref. conversion ?

    Hank,
    Glad to see that you are still around. Some time ago you had issues with oil return in a R-508B system but you never let us know if you solved it and if so how. Please let us know.

Similar Threads

  1. Pressure to Temperature Conversion
    By cryptojoe in forum Technical Speculations
    Replies: 5
    Last Post: 13-04-2010, 12:42 PM
  2. Propane Refrigerator Conversion
    By zolar1 in forum Refrigerants
    Replies: 26
    Last Post: 04-02-2007, 04:42 AM
  3. R12 to R134A conversion
    By northern-tech in forum Commercial
    Replies: 8
    Last Post: 26-06-2006, 06:24 PM
  4. Horsepower and Kilowatts
    By baker in forum Air Conditioning
    Replies: 4
    Last Post: 23-03-2004, 10:17 AM
  5. Horsepower = Tonnage
    By acman in forum Fundamentals
    Replies: 9
    Last Post: 31-05-2003, 03:10 PM

Posting Permissions

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