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  1. #1
    Join Date
    Apr 2018
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    Hello, i am working on a frozen food storage project where we are looking on optimizing its ammonia refrigeration plant.
    There are 5 storage rooms and each of them have 2 evaporators with direct cooling.
    There are two 2-stage sabroe compressors working in parallel with cold gas intercooling.
    And an air cooled condenser sitting on the roof of the building.
    The condenser fans have EC motors with 50% and 100% speeds.

    The plant is found in the north of Norway with colder temperatures most of the year.

    My question comes to the condenser.

    We will like the condensing temperature to float in relation to the ambient air, but with different given temperature approaches so that the condensing temperature ranges between 13C and 23C.

    I have been told by a former university lecturer of mine that the temperature approach is a fixed value for condensers.

    My question is can the temperature approach not be adjusted to different values ? Some examples can be 15C, 20C, 25C.

    If yes how can this be done ?

  2. #2
    Join Date
    Jan 2013
    United Kingdom
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    I think you are mixing up Approach with Condensing Pressure/temps. The approach is an indication of the thermal efficiency between the refrigerant temperature and the medium used, in this case air, in most cases it is water. The lower the approach the better the efficiency in heat rejection.
    I think what you are looking for is a way to regulate the condensing pressure, if you have EBM EC fans then they have an inbuilt VSD , currently you seem to be using a two step control 50% and 100% , but the fans are capable of variable control based on a voltage input from a pressure transducer located in the condenser , so you just have to fit a discharge pressure transducer and wire it in too 1 fan then slave the other fans from that, all fans will then operate at the same speed , ramping up and down based on the setpoint you put into the master fan. You need to use the EBM EC fan software to configure the control pressures, response and ramping required, contact your local EBM dealer and they will support you on this. If in doubt RTFM.

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