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  1. #1
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    Non Condensable Gas Concentration In Liquid Refrigerants



    I have an important NCG question I was hoping one of you engineers could maybe help me with? We all know that the air concentration in the vapor space above a cylinder of R-22 goes up as temperature goes down, due to the condensation of the refrigerant. My question is, what happens to the concentration on the air in the liquid phase in that same tank as the temperature goes down? Does is act like CO2 in water and become more soluble? Or does air act differently in refrigerant and actually decrease in the liquid, with decreased temperature, as it increases in the vapor?

    Thanks.



  2. #2
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    Re: Non Condensable Gas Concentration In Liquid Refrigerants

    .

    As far as I'm aware air does not react with refrigerant.
    Air is Not solubal and will always remain as air and it
    will always find the highest part of the cylinder (or fridge system).

    Air is a non condensable gas because the pressure inside most systems
    is not high enough for air (N2 & O2) to saturate. Its volume can change
    but it will never saturate at normal refrigeration pressures.
    The result is air just sits there and takes up space. If air takes up space
    the refrigerant can't do its job, which in most cases is condense.

    Regards

    Rob

    .
    Last edited by Rob White; 17-07-2012 at 08:32 AM.

  3. #3
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    Re: Non Condensable Gas Concentration In Liquid Refrigerants

    besides, it can contribute to oil contamination/carbonization , sludge formation due to heat since condensing pressure & temp would go up ..................

  4. #4
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    Re: Non Condensable Gas Concentration In Liquid Refrigerants

    The way I understand it If air is in top part of full or partly full refrigerant bottle, the pressure will be higher than its saturated temp.
    Same as if mixed gases the pressure won't match saturated temp of that refrigerant.

  5. #5
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    Re: Non Condensable Gas Concentration In Liquid Refrigerants

    Hi Ranger
    You are right, when there are non-condensables in a system yous Dalton's Law - The total pressure of a mixture of gases is equal to the sum of the partial pressures that each gas would exert if they occupied the space alone. PT = P1 + P2.
    This is how you determine if a system has non-condensables.
    Regards
    Paul

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