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  1. #14
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    I doubt you'd get any noticeable gain in efficiency by using the condensate to cool the liquid refrigerant. But, if we use an extreme example, and you were to cool the liquid too much, then your metering device would be over sized.
    If you were a real tech, you'd solder a relay on that board and call it good to go.

    I do a triple evac with nitro to remove non condensables.

    I use 56% silver on everything except steel.

    Did you really need the " If you were a real tech " ??

  2. #15
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    Why is that?
    Quote Originally Posted by BBeerme View Post
    I doubt you'd get any noticeable gain in efficiency by using the condensate to cool the liquid refrigerant. But, if we use an extreme example, and you were to cool the liquid too much, then your metering device would be over sized.
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  3. #16
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    Lets just say that the heat exchanger is a miracle of engineering and cools the 100* liquid to 50 or lower. How would that affect the metering device?

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  4. #17
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    I am assuming that if the liquid is 100* or 50* the volume probably stays fairly consistent. And i am also going with a pressure of 110* for whatever refrigerant this theoretical system may be. So the 50* liquid has 60* subcooling. It can absorb enough heat to raise its temp 60*.

    I know this probably splitting hairs since the amount of heat required to raise the temp of liquid is small compared to the amount it takes to boil it. But it gets the gears moving in my brain and sometimes i learn something totally new or finaly understand something i thought i knew

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  5. #18
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    At the outlet of the metering device is flash gas. That liquid refrigerant flashing [boiling] does nothing to cool the environment, all it does is cool the liquid to the saturation pressure.

    If, as in my extreme example, the liquid is already at the saturation temperature, then you'll have too much liquid in the evap. And you would need a smaller metering device to throttle more of that liquid entering the evap.


    Quote Originally Posted by R600a View Post
    Why is that?

    Sent from my rotary telephone using Tapatalk
    If you were a real tech, you'd solder a relay on that board and call it good to go.

    I do a triple evac with nitro to remove non condensables.

    I use 56% silver on everything except steel.

    Did you really need the " If you were a real tech " ??

  6. #19
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    Ok i think i am getting your point now.
    I addressed that in the original design by using a txv. That is why i was wondering if it would do the same amount of cooling with less mass flow and cause higher head pressure.
    What do you think?
    Quote Originally Posted by BBeerme View Post
    At the outlet of the metering device is flash gas. That liquid refrigerant flashing [boiling] does nothing to cool the environment, all it does is cool the liquid to the saturation pressure.

    If, as in my extreme example, the liquid is already at the saturation temperature, then you'll have too much liquid in the evap. And you would need a smaller metering device to throttle more of that liquid entering the evap.
    Sent from my rotary telephone using Tapatalk

  7. #20
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    I sort of think i answered my own question. I think that the amount of heat capacity gained by an extra 50* subcooling would be just a drop in the bucket compared to the latent heat of evaporation that the refrigerant already has since we are keeping the pressures constant i dont think the amount of work the compressor does would change and we would just have created a system that was far more sensitive to what we pour down the condensate line and the only benefit would be if we were low on charge we could maintain enough subcooling to not loose performance.
    Am i right?

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  8. #21
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    Ok i am not shure where i would find the numbers for normal refrigerants so i will use r718 here goes.
    So 1 btu raises 1lb of r718 1*
    970.4btu will vaporize 1lb of r718

    So a 3 ton system would have a mas flow rate of 37.09810387469lb/hour

    And we would gain 2225.88623248btu/hour
    So our 36000btu system would move 38225.88623248btu/hour

    Thats not as bad as i thought but i don't know the numbers for r22 or r410a

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  9. #22
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    Here's another consideration for you.

    The higher the suction pressure, the greater the capacity of the compressor.
    If you were a real tech, you'd solder a relay on that board and call it good to go.

    I do a triple evac with nitro to remove non condensables.

    I use 56% silver on everything except steel.

    Did you really need the " If you were a real tech " ??

  10. #23
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    I could be wrong but i think the suction pressure would stay roughly the same.
    I know i could increase capacity by running the coil at 50* instead of 40* but then i lose latent capacity. And i am investigating the affect of free subcooling at the moment.
    Quote Originally Posted by BBeerme View Post
    Here's another consideration for you.

    The higher the suction pressure, the greater the capacity of the compressor.
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  11. #24
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    How should i understand these numbers?
    R22@ 40* 83.28 psia 21.688btu/lb liquid enthalpy 108.191btu/lb vapor enthalpy

    Do those numbers tell me the latent heat of vaporization? If so which one?
    Why do liquid and vapor have different numbers at the same temperature and pressure?

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  12. #25
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    I think the term is net refrigeration effect and it would be the difference between the two enthaly #s you listed

    Side note order up a copy of "pressure enthalpy without tears." recommended reading if you havent already

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  13. #26
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    I thought of another non conventional idea. What effect would it have if you put the txv outside?
    Just weld it in after the liquid line service port, weld an equlizer port in the vapor line to leave your service port open, strap the bulb to the vapor line and insulate the liquid and vopor lines really well. Also remove the piston of course.

    Do youall think it would work like normal or would it effect the efficiency?

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