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Thread: Peltier cell questions

  1. #1

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    Hello all,
    1) I was wondering whether all of the heatsinks on eBay said to fit computers would work with a peltier cell?

    2) Also, If you can hook up a peltier cell like a CPU fan with just an adapter, or if the power is to great?

    3) Do you think just one cell is enough for a 24 gal tank?

    4) If not, do you think I could get a smaller second one and hook it up to the same heat sink?

    5) How would I go about waterproofing the peltier cells and or heat sinks, or should I just try to pipe in the cold air?

    Thanks!! [img]http://www.**********.com/iB_html/non-cgi/emoticons/biggrin.gif[/img] [img]http://www.**********.com/iB_html/non-cgi/emoticons/smile.gif[/img] [img]http://www.**********.com/iB_html/non-cgi/emoticons/alien.gif[/img]

    Here is the heatsink

    here is the peltier cell.
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  2. #2
    Tony Paroubek's Avatar
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    The coleman and igloo portable coolers that can work plugged into a car lighter socket work on peltier cells. I know of one person that has built a mini ultrahighland grow chamber using one of these coolers. Essentially the same as using a chest freezer setup but on smaller scale and different cooling system.

    Peltier cells get pretty cold. They also generate alot of heat on the other side. To cool a terrarium you would need to figure out how to get the cold off the peltier and into the grow chamber and also effectively cool the heat sinks on the other side. I would imagine the effectiveness of the set up would depend on many factors. Such as:
    How much of a temperature drop are you trying to achieve.
    How large is the area needing to be cooled.
    How effective is your system to move the cold off the peltier and also remove the heat from the other side.
    How well insulated is the grow chamber.
    Is that a Nepenthes in your pocket or you just happy to see me?

  3. #3

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    Thanks Tony!! Here are my plants, unless you have any suggestions... It is a 24 gallon tank. I would put styrofoam around the back and sides. I plan to have the unit mounted on top and have the heat sink blow the warm air most likely into a water reservoir, or pipe it to the lowland tank. the peltier cell would be just inside the top of the tank, and I would mount a fan on the top side next to it to blow the cold air around the tank. I am aiming for a 15-20*F cooling effect. If you think it would work, I could just wrap it in aluminum foil where it would be in the tank, to enlarge the area dissipating cold, and water proof it from humidity. Do you think it works on power adapter plugs like a CPU fan? Thanks again!! [img]http://www.**********.com/iB_html/non-cgi/emoticons/biggrin.gif[/img] [img]http://www.**********.com/iB_html/non-cgi/emoticons/smile.gif[/img] [img]http://www.**********.com/iB_html/non-cgi/emoticons/alien.gif[/img]
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    Tony Paroubek's Avatar
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    Thoughts on your plans:

    Blowing the warm air off the heatsink side into a lowland terrarium: Fine for warming the terrarium but will drastically drop the humidity of the lowland chamber as you pump all that air into it. So need to address that issue if you plan to use the warm air for that purpose.

    For best efficiency you should have a heatsink on the one side disipating the heat and on the growchamber side a cold sink to better disipate the cold off the cell. As far as I know (which is only minimal when dealing with peltier cells) The better the heat and cold sink the better they operate. Quality copper or aluminum cpuheat sinks with integrated cpu fans mounted right to the peltier with thermal conductive glue would be best. So basically you need a hole in the grow chamber to place the cold sink through and seal up around the edges. I am guessing that a 250watt computer power supply would do nicely to run up to 2 peltiers and 4 fans if you wanted to add a second one.

    I have no idea how much cooling effect you could achieve with one cell. Insulating around the sides and back will help alot. I think it is highly dependent on the quality of the heat and cold sinks and their ability to move the heat and cold off the surface of the cell.
    Is that a Nepenthes in your pocket or you just happy to see me?

  5. #5

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    Thanks Tony. I've never heard of a coldsink before, but wouldn't the aluminum foil wrapped around the cold side fairly thickly do the same thing? Also, I'm not enough of a computer person to know the difference between a CPU power supply and a normal one. All I know is that the fan that I run for air circulation is hooked up to an adapter that I connected to the CPU fans wires, and it works fine... Thanks again!! [img]http://www.**********.com/iB_html/non-cgi/emoticons/biggrin.gif[/img] [img]http://www.**********.com/iB_html/non-cgi/emoticons/smile.gif[/img] [img]http://www.**********.com/iB_html/non-cgi/emoticons/alien.gif[/img]
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  6. #6
    It's been one of dem days BigCarnivourKid's Avatar
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    The key to a heat/cold sink is surface area. A lump of foil has less surface area than a heatsink made out of the same amount of foil. Instead of a lump of foil, hook up a heatsink to it or reverse the polarity of your hook up and the heatsink becomes a coldsink and the flat side of the peltier becomes a miniature heater/hotplate.

    Maybe an overclocker out there will have another idea.

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    Ok, but I could use a LOT of foil, and I have an idea for surface area, but its hard to explain... Thanks again!! [img]http://www.**********.com/iB_html/non-cgi/emoticons/biggrin.gif[/img] [img]http://www.**********.com/iB_html/non-cgi/emoticons/smile.gif[/img] [img]http://www.**********.com/iB_html/non-cgi/emoticons/alien.gif[/img]
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    Tony Paroubek's Avatar
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    Think of a coldsink the same as a heatsink except instead of trying disipate excess heat your disipating excess cold ;>

    Aluminum is a good conductor of cold/heat (copper is even better) but aluminum foil is to thin to do it well. You will also have a hard time getting good contact with the peltier. Ideally you should have a heat/cold sink bonded to the entire surface so you can maximize it's abilities.

    I only mention a computer power supply because they are easy to find along with heatsinks and cpu fans. If the fans and peltier are 12v (which they most likely will be) then any 12v powersupply will work as long as it has enough watts to run everything.
    Is that a Nepenthes in your pocket or you just happy to see me?

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