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expands

when water turns to steam at atmospheric pressure it expands 700 times it's size.



What about refrigerants? And in a condenser, when the refrigerant turns back into a liquid, how much does it's size reduce?



Just thinking. Maybe too much.

Comments

  • TechmanTechman Member Posts: 2,144
    expands

    Hi Paul I beleave that is 1700 times expansion for water to steam and I too have wondered about the freon rate of expansion
  • Paul Fredricks_3Paul Fredricks_3 Member Posts: 1,549
    oh

    yeah 1700
  • Brad WhiteBrad White Member Posts: 2,393
    edited March 2011
    Specific Volume Equation

    Now you are having me dig out the old books...



    As you know, the specific volume (CF/lb, M^3/kg, however expressed), of any gas is a function of its pressure (and incidental temperature, which in refrigerants go especially hand-in-hand).



    From my tables...



    For steam, at 0 psig (atmospheric, saturated condition), the water state is 0.016715 CF/lb. and steam vapor at the same pressure is 26.78 CF/lb. This is an increase of 1670.8. close enough to the 1700 factor.



    At 2 psig, this ratio drops to 1419.7 and at 100 psig, drops to 218. Steam specific volume at 100 psig is 3.8925 cubic feet per lb. compared to 26.78 at atmospheric pressure, so you can see how fast steam will travel when released.



    I will let the good professor speak to refrigerants. They are all different of course and I am curious about the correlation now myself. :)
    "If you do not know the answer, say, "I do not know the answer", and you will be correct!"



    -Ernie White, my Dad
  • Paul Fredricks_3Paul Fredricks_3 Member Posts: 1,549
    OK

    In the condenser coil the pressure is what the pressure is. May question may not matter because the pressure...is what it is. I'm wondering if the refrigerant changing to a liquid causes the pressure to be less? I figure it must which is why the pressure rises if you block the coil: Less refrigerant changes state. Of course it's also hotter which causes more expansion of the gas. Maybe both are to blame.



    I have a headache.
  • RDSTEAMRDSTEAM Member Posts: 134
    pressure will drop

    when it hits the metering device, thats what causes your liquid refrigerant to begin to boil.
  • Paul Fredricks_3Paul Fredricks_3 Member Posts: 1,549
    yeah

    got that. I'm talking about in the condenser only.
  • TechmanTechman Member Posts: 2,144
    Paul I have an asprin.

    Professor SILBERSTEIN TO THE RESCUE , i HOPE! I think that there is a pressure drop at the  condensing stage,but in a system that is on ,it's kinda fed  a steady diet of new freon  & until the load drops  and  then there's a little less diet  so ,less pressure on my gauges. I think  ! And I also think you are right about them being connected ,the good old P/T or T/P chart
  • Paul Fredricks_3Paul Fredricks_3 Member Posts: 1,549
    Just thinking

    Maybe too much. Non condensables in the system keep the high side pressure up, not because they are hot, but because they don't condense. So the pressure doesn't drop due to change of state, from gas to liquid, because there isn't a change of state.



    That probably answers my question. For now.



    Thanks everyone.
  • jp_2jp_2 Member Posts: 1,935
    no change of state, no cooling

    how can you have cooling if the refrigerant doesn't change state?



    isn't that what its all about, going from a liquid to gas?
  • Paul Fredricks_3Paul Fredricks_3 Member Posts: 1,549
    yeah

    except I was talking about the condenser. Of course, if it doesn't condense, no liquid to later vaporize and cool.
  • TechmanTechman Member Posts: 2,144
    edited March 2011
    expands

    The non-condensibles do not condense ,the freon still does condense,@ a higher temp/press and @ a higher cost. Water ( one lb ) @ 211* needs only 1btu to go to 212* water then it needs 970 btu to change to 212* steam. What is the freon rate of expansion?
  • jp_2jp_2 Member Posts: 1,935
    whats a non condensible ?

    in a cooling system?
  • TechmanTechman Member Posts: 2,144
    edited March 2011
    Stuff

    like air &nitrogen left in a system or letting the air in ur hoses get into the system.
  • RDSTEAMRDSTEAM Member Posts: 134
    what is it

    that you are trying to solve?? are you just wondering what the expansion rates are or are you problem solving a system.
  • jp_2jp_2 Member Posts: 1,935
    rate of expansion

    I would guess the rate of expansion for the freon, practically speaking would be instantaneous.  unless it had a rather large back pressure to deal with.



    I've always wanted to know the force of expansion, water to ice.   ice breaks a lot of stuff.
  • Paul Fredricks_3Paul Fredricks_3 Member Posts: 1,549
    No

    Just thinking out loud...or out web. Just trying to think like refrigerant. Kind of like trying to think like steam to get a better idea of the inner workings of a steam system.
  • Tom Blackwell_2Tom Blackwell_2 Member Posts: 126
    ideal gas

    Refrigerant gasses behave as an ideal gas, i believe; that is they will expand to the ratio of the absolute temperature ratio. The gas leaving the compressor is heated by the heat of compression and by the motor in a hermetic compressor. In a condenser coil, the pressure is that point at which the gas turns into a liquid. This would be the condensing temperature, and the pressure would correspond to the saturation temperature of the refrigerant. If non-condensables are present, then the pressure will be higher than the saturation point, but this would be evident only if accurate temperatures are known. The amount of charge in the system determines how much of the condenser coil is filled up with liquid and can be measured by the amount of liquid subcooling. If the coil had no stored liquid, then the liquid temperature would be the same as the condensing temperature. The amount of liquid subcooling has a great effect in the capacity of the metering device, particularly capillary tubes. My apology for the rambling nature of this post-just tying strings of thought togrther.
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