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  1. #1
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    Making a simple water cooled condenser



    How long of copper tube of 1/4 size would I need to make a 3,100BTU water cooled condenser?

    I plan on using a 1/2" PEX water pipe as the jacket and cooling the 1/4 inside.

    I tried searching the forum but couldn't find any info on the heat rejecting ability of 1/4" copper per foot with a 10K delta-T.

    I'm thinking with a 16C inlet temp I'd guestimate 6 feet or so?

    Basicly I want to figur out how many BTU per foot of 1/4 at a dT of 10K in a water cooled aplication.



  2. #2
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    Re: Making a simple water cooled condenser

    This is exactly he same way the evpaorators are working on some Trumpf lasers we're servicing.

    In attachment a Kelvinator document from just after WWII. Got it some time ago from a RE poster
    Hopes this is of any help even if it's ancient.
    I have another for cooling but it is 105kB large, so too big to post here.
    Anyone has a tool to reduce this size?
    Attached Files Attached Files
    It's better to keep your mouth shut and give the impression that you're stupid than to open it and remove all doubt.

  3. #3
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    Re: Making a simple water cooled condenser

    Ok cool, so I'm figuring about 100 BTU per 2.4 F^2, but I'll be using it in the revers, but I supos it works all the same only the water is cooling it.

    So 3100BTU * 2.4 = 7440 squar feet of tubing? Thats doesn't sound right to me.

  4. #4
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    Re: Making a simple water cooled condenser

    Peter_1,Download Winzip or WinRar free off the web or send your email address. You can use any of these to reduce the file.I'm salivating at the thought of it so...

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    Re: Making a simple water cooled condenser

    Quote Originally Posted by The MG Pony View Post
    How long of copper tube of 1/4 size would I need to make a 3,100BTU water cooled condenser?

    I plan on using a 1/2" PEX water pipe as the jacket and cooling the 1/4 inside.

    I tried searching the forum but couldn't find any info on the heat rejecting ability of 1/4" copper per foot with a 10K delta-T.

    I'm thinking with a 16C inlet temp I'd guestimate 6 feet or so?

    Basicly I want to figur out how many BTU per foot of 1/4 at a dT of 10K in a water cooled aplication.
    Thats fairly simple but you have a couple of figures missing.
    Using the formula Q = U A LMTD for a cross flow heat exchanger you can find A by transposing.

    We know that Q = 3100btu's or 908.3W
    U (for copper) = 385
    A = the area of copper tube ( for the length divide the answer by Pi r^2)
    LMTD = (shell & tube) (Q = UAd lmtd)
    Shell = (Q = mcd lmtd)
    Tube = (Q = mcd lmtd)

    So, to complete the formula, we need to know the refrigerant entering and leaving temperature and SHC. From what you state, we assume that you are using water as the cooling fluid with an entering temp of 16 and a leaving temp of 6 (dt = 10K)

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    Re: Making a simple water cooled condenser

    Lets assume the average of the discharge of R-22 and of R-134a in a fridge/freezer aplication entering refrigerant and a goal of 30 out or better

    Would the average discharge be round 60C?

  7. #7
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    Re: Making a simple water cooled condenser

    Oh, I forgot - we need the expected mass flow rates as well

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    Re: Making a simple water cooled condenser

    About 20.84 Kg/H (45.86 pounds/H)
    Last edited by The MG Pony; 31-05-2007 at 11:34 PM.

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    Re: Making a simple water cooled condenser

    I assume that this is the cooling water? Great.

    All we need now is the refrigerant side (shell?)

    Then we can feed the info into the formula

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    Re: Making a simple water cooled condenser

    Oh no thats the refrigerant, sorry.

    Water would be 818.3L/h (180 gallons(UK)/H)

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    Re: Making a simple water cooled condenser

    *Nickers" Any one? *Trots off*

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    Re: Making a simple water cooled condenser

    Help? How do I assemble the formula?

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    Re: Making a simple water cooled condenser

    Quote Originally Posted by The MG Pony View Post
    Help? How do I assemble the formula?
    Hi MG Pony

    I attached to you a file in which i made for you a rough estimation. Check it and if u need further discussion I'd like to be in ur service. I wish it could help

    Best regards
    Attached Files Attached Files

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    Re: Making a simple water cooled condenser

    Thank you but I don't understand, The pex is holding the water, and inside the pex will be the copper tubing of 1/4. So do you mean I need 6 feet worth of copper tube in a pex jacket?

    I'd realy enjoy learning how to assemble then compile the formula, as it is one I feel I'll be oft needing. Math has all ways been my weak point unless it is working on some thing physical, I'm very practical learning slanted.

    Or do I need five 6foot tubes in a water jacket?
    Last edited by The MG Pony; 22-06-2007 at 07:45 PM.

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    Re: Making a simple water cooled condenser

    Sorry MG, just read your recent replies and it's been a s**t day today so I'll feed your info into the formula over the weekend.


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    Re: Making a simple water cooled condenser

    Ok thank you.

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    Re: Making a simple water cooled condenser

    Quote Originally Posted by The MG Pony View Post
    Thank you but I don't understand, The pex is holding the water, and inside the pex will be the copper tubing of 1/4. So do you mean I need 6 feet worth of copper tube in a pex jacket?

    I'd realy enjoy learning how to assemble then compile the formula, as it is one I feel I'll be oft needing. Math has all ways been my weak point unless it is working on some thing physical, I'm very practical learning slanted.

    Or do I need five 6foot tubes in a water jacket?
    You Welcome, Yes five 6 foot copper tubes in a water Jaket... I attached to u new file to demonstrate further the calculations.

    Cheers
    Attached Files Attached Files

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    Re: Making a simple water cooled condenser

    Ok I get it now, thanks, I was intending to wind the tube in a spiral to reduce the space that it would take up.

    I apreciate all the work you have don, I'll have to re-read it a fiew times in the morning to under stand it better, but I sor tof get it.

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    Re: Making a simple water cooled condenser

    Quote Originally Posted by The MG Pony View Post
    Ok I get it now, thanks, I was intending to wind the tube in a spiral to reduce the space that it would take up.

    I apreciate all the work you have don, I'll have to re-read it a fiew times in the morning to under stand it better, but I sor tof get it.
    U welcome at any time

    Cheers

  20. #20
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    Re: Making a simple water cooled condenser

    We never did finnish this, I would assum it works in the revers too!

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