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Thread: HEATPIPES (Thermal syphone)

  1. #1
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    Default HEATPIPES (Thermal syphone)

    Dose any body know anything about useing Heat pipes?
    I am looking into useing heatpipes to remove heat from a laser modules.
    would this be practical and effectiant way of removing the heat (cooling the laser within operating peramiters). This would be for a two watt laser module times three (6watts toltal) pluss drivers, pluss galvos, and maybe even the three T.E. Cooling chips.

    My Q's are:
    0) how hot is a 2 Watt laser module going to get?
    1) What would be the best fluid to use?
    2) What size tubbing inside diameter would be best?
    3) how long should the heatpipe be?
    4) how many individule heatpipes should be considerd for one module?

    I have some knowladge of them and how they work, and how to asemble a working one. Must be in a vaccume and fluid amount is less than 1% by volume of the volume of the heatpipes toltal volume. I also know about the capulary wicking needed for those heatpipes that are horizontal in use, and I know most of the types of fluides they use in them for the different heat ranges.
    I have made some useing Butane and some useing Methanol, both worked but the fluid levels were not right and they leaked over a period of three days to a non working status. So I gusse sealing them up while they contain a vaccum and keepping 1% fluid by volume and making the seal permenetly is the hard part.
    Any insite from any one would be helpfull.
    Thanks
    BEAMANN (GODSLIGHT SHOWS)

  2. #2
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    I'm facing right now cooling issues in the design of my new case, and I wondered too if heat pipes would work. I have 4 watts of laser power and their power supplies on the same 10mm thick alu plate (on the other side), the supplies side is cooled with some big heat sinks and with a constant airflow, but that's not suffisant, these damn TEC are heating like hell.

    But first an important question : will the heat pipe work if positionned upside down?? Is there gravity independant pipes on the market?

  3. #3
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    from what i understand, a heat pipe is not a cooling solution by itself.

    it just transfers heat from one place to another, so you would still be in need of a cooling solution (i.e a heatsink and fan)
    "its called character briggs..."

  4. #4
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    Of course, it was implied The easiest solution would be to find computer heat sink based on heat pipe.
    The problem is we need one with big contact surface, and those for CPU have usually smaller one...

  5. #5
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    I did some work with heat pipes and computer graphics card.

    It depends what the TDP of the laser units is as to how many / how much you'd need to transfer heat away from a smaller heatsink to a larger unit.

    For graphics cards with a TDP of about 125w we used 2/4 pipes of about 20mm going from a polished copper block through to a larger heatsink with fan.

    The length of heatpipe should be dependant on where you want it to go to, although if I remember correctly, keep it as short as is needed.

    Have a look on ebay for older / broken graphics cards, you can normally get a good copper plate, heatpipes and heatsinks from those units. An NVIDIA 7900GTX is a good example which you should be able to find.

    ( http://cgi.ebay.co.uk/ASUS-EN7900-GT...item27b96e9462 ) - One example

    To be perfectly honest there are probably easier (and maybe cheaper) ways to cool laser components, as most people here appear to use a large baseplate, fans etc and have no problems...

    Keep It Simple Stupid - Always served me well in the past, make a design too advanced and theres more things to go wrong (more things to damage other components!).

  6. #6
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    I think its more of a design problem and that why the request for the heat pipe

    If you use tecplates the beamheight will be higher and when you want to match it with lets say a laserwave its very difficult to design something that can stack beams without getting it to high at aperture. But a heatpipe is an interesting idea to work with

  7. #7
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    I havea 12" by 18" 1 inch thick alum baseplate and am running 2 watts blue, 1.5 watts of red, and 500mw green with my power supplies mounted on the bottom with the drivers for the scanenrs and lasers bolted to the plate. I have ZERO heat issues even after hours of running. The plate gets warm like someones forehead when they are sick and that is all.

    So where is all your heat coming from?

  8. #8
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    The TECs would be my guess, they are not magic and the energy you put into them as electrical power comes out as heat in addition to the heat they pump.

    If you have 2W of say 445 that means about 8W of heat load from the diodes, add a TEC and you may need to remove twice that, maybe more, depends on the delta T across the TEC.

    Regards, Dan.

  9. #9
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    Quote Originally Posted by sbk View Post
    I'm facing right now cooling issues in the design of my new case, and I wondered too if heat pipes would work. I have 4 watts of laser power and their power supplies on the same 10mm thick alu plate (on the other side), the supplies side is cooled with some big heat sinks and with a constant airflow, but that's not suffisant, these damn TEC are heating like hell.

    But first an important question : will the heat pipe work if positionned upside down?? Is there gravity independant pipes on the market?
    Are talking about using a H/P upside down or a Thermal diode?
    A Vertical type heat pipe will work the same from both ends as long as thair is a pressure differance between both ends.
    a Thermal diode will not It's different TECH in valved
    YES you can find a heat pipe that use wicking to compleete the thermal loop. I have used succesfully desoldering wick inside some of my EXP and got a reverse flow, barly! Now I whant to try capulary tubing inside heat pipe tubbing to see if I can get a better result.
    Last edited by beamann; 03-17-2011 at 20:05. Reason: adding more TXT
    BEAMANN (GODSLIGHT SHOWS)

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