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  1. #1
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    Thermostatic expansion valve orifice size for variable loiads



    I would like to have ideas when selecting the orifice size for variable loads like ice cube makers or ice cream batch freezers. Where the refrigeration load is different at the beginning of the freezing cycle from the load at the end of the freezing cycle.

    When selecting the size of the orifice, should we consider the load at the beginning of the freezing cycle, the load at the end of the freezing cycle or the load at middle point?



  2. #2
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    Re: Thermostatic expansion valve orifice size for variable loiads

    you size with your peak load which is the initial load value at the beginning of the cycle.

  3. #3
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    Re: Thermostatic expansion valve orifice size for variable loiads

    when you design system you calculate all load then you choose in how many hours you want to cover it
    and then you choose your compressor - condenser and evaporator and...

    In cool rooms :
    your size comes from your evaporators capacity (actual evaporator capacity = evaporator loads-type of gas you choose- rooms temp -evaporator temp. and humidity )) when you choose size you should look for drop pressure in expansion valve --((discharge pressure - suction pressure))

    In this type of work it comes from evaporator capacity ( when you choose size you should look for drop pressure in expansion valve --((discharge pressure - suction pressure))
    Last edited by mbc; 25-07-2014 at 06:02 AM.

  4. #4
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    Re: Thermostatic expansion valve orifice size for variable loiads

    yup as said befor, you start with your heat load total / by time this gives the evap and TXV needed (But the final txv will be determined by plant)

    With total BTU/H we can size a plant, for this we need to know ambient, Compressor is sized for load, condenser is sized for ambient heat with some head room.

    For example: My place needs 1.5tons of cooling for air conditioning My txv will be from 2.02tr to 1.5tr through its operating range based on sub cooling.

    I have a 17000BTU/H rotary compressor and I am using a 2 ton condensing coil with a fan cycling switch.

    These combinations maximizes the efficiency and performance of each system.

    the natural function of a txv will reduce capacity as the load pulls down.
    Now in Redvers Sask.

  5. #5
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    Re: Thermostatic expansion valve orifice size for variable loiads

    You Can choose the TXV and orifice @ design condition. Choose the one which loads 80%(TXV loading) at design condition , so that it gives enough capacity during pull down. As you know the valve capacity depending on the pressure drop across it. I generally select valve loading 80% and generally do not find any capacity issues with varying load

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