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Thread: R134a to R407C

  1. #1
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    tooltemp Guest

    R134a to R407C



    Hi
    I'm looking at a job where the packaged water chiller is running on R134a. The chiller has 4 off MTZ160-4 Manurope compressors fitted, running as two circuits. Air cooled condensors and 2 plate heat exchangers. Internal ciculation pump and process pump.

    The ciller is being used to cool the hydraulic oil on a press. The press is fitted with a 185kW process motor and a 5.5kW recurculation motor.

    We have already decided that the 2 heat exchangers fitted are too small. However there is a concern that the ciller also does not have enough capacity so I'm considering changing it to R407C.

    Perameters at the moment on 134a are:

    Evap Temp - 6.5'C
    Condensor Temp - 50.0'C
    Measured super heat - 10'C
    Set point-11'C
    Acutal temp - 12.6'C
    DT on flow & return - 5'C
    Flow rate to process - 227l/min

    What sort of gain in duty could I expect from changing to R407C? Also I know I will need to change the TEV orifices, any thing else that would need to be changed?

    Lots of questions I know, but any help would be great.

    Thanks



  2. #2
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    Re: R134a to R407C

    Those compressors have a capasity of 24,2 kW each at 6/50*C, 10K superheat and zero subcool with R134A. Power consumption 8,1 kW each.

    With R407c you get 37,2 kW each at 8/52*C dew point. Power consumption 13,2 kW each.

    An other alternative is R404a. Capasity 36,4 kW and power consumption 14,9 kW each at 5/50*C.

    You need to increase the capasity of both the evaporator and the condensor.

    What is the in/out temp of the oil at 6,5*C evaporating?
    Last edited by SteinarN; 15-05-2008 at 03:07 PM.

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