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  1. #1
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    Question Change Mayekawa Chiller from R-22 to R-507



    Hello. I just discovered this site and am hoping someone can steer me in the right direction. Let me start off saying that I am a plant engineer, not a refrigeration engineer. I know enough about refrigeration to annoy the chiller repairmen, but that is about all.

    My plant has two chillers supplied by a now out of business company named McCormack Manufacturing. The chillers are about 16 years old, are rated at 12 tons capacity, and are water cooled. The chillers have screw compressor/oil separator units made by Mayekawa. The compressor is a model 125LUD-HX-SU. The chillers are charged with R-22 refrigerant. The coolant used is D-Limonene and we are controlling the leaving water temperature at -28 F. Suction pressure is in the 0-3 psi range and the discharge pressure is in the 190-210 psi range.

    We have to either retrofit the chillers with another refrigerant or replace them with new machines using a different refrigerant. It has been suggested that R-507 might be the best alternative refrigerant to use in this application.

    My questions are:

    1. Is R-507 the best refrigerant to use for replacing the R-22 in this type of application?

    2. What are the negatives for retrofitting the existing chillers with R-507 (or a different one if it is a better choice)? Would I have to change major components like a compressors, compressor motor, evaporator, or condenser?

    3. The Dupont information for Suva R-507, says that R-507 gives a slight increase in capacity at the temperatures we maintain. Is that true or just advertising hype?

    4. What kind of operating temperatures and pressures should I expect?

    Thanks for your time.

    3. How much



  2. #2
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    Re: Change Mayekawa Chiller from R-22 to R-507

    Around 50% increase in drawn power with 507., so new motor and starter equipment, new condenser, new expansion valves. Oil changes and flushing. Time consuming and expensive project. Plus more expensive to operate.
    I would recommend a new ammonia compressor skid using a plate HX evap and HX condenser. More efficient and eco freindly. ( no carbon taxes ) Cost comparative in the long term compared to retro-fit.

  3. #3
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    Re: Change Mayekawa Chiller from R-22 to R-507

    plantengmi,
    If you visit DuPont website it will recommend types to retofit R22.
    You can also download pressure/temp programme to see different refrigerants & how they behave.
    It does mention that can R507 can be used as a retrofit but appears to more suitable for a R502 system.
    There may be a mix up somewhere.
    It should be straight forward with minimal or no changes at all.
    Can you tell us type of the system eg flooded or DX etc.
    Last edited by RANGER1; 29-08-2012 at 11:13 AM.

  4. #4
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    Re: Change Mayekawa Chiller from R-22 to R-507

    The evaporator has the coolant on the shell side and refrigerant on the tube side. There is a TX valve on the entering refrigerant line. From what I have read, this means the evaporator is a direct expansion type.

    As far as the suitability of R-507 in this application, in their tech bulletin ART-37, Dupont has information for retrofitting both R-22 and R-502 systems with either Suva 404A or Suva 507.

    Is there a different refrigerant that might be a better fit for this particular chiller at the -28F temp we are maintaining?

    Thanks

  5. #5
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    Re: Change Mayekawa Chiller from R-22 to R-507

    I have no experience with an ammonia system and the plant has never had one. I am not sure how well the idea would go over. In general, how does an ammonia system compare with an HFC system as far as cost, size, or efficiency?

    Thanks

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