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Improving my peltier device - need to cool water to 50 degre

 Post subject: Improving my peltier device - need to cool water to 50 degre
PostPosted: Fri Oct 09, 2015 8:27 am 
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Joined: Fri Oct 09, 2015 7:59 am
Posts: 1
Hey guys,
I am in the process of building a device that uses peltiers to cool water. I need to be able to cool this water to around 50 degrees f. The volume is 3 gallons of water.

The first device I build used 2x 12710 peltiers. I attached an image below. The peltiers were supposed to be 10 amps, but in reality were only pulling 4 amps each. This worked pretty decently, but plateaued to 61 degrees f (ambient air temperature was 78.4 degrees f, and the heat sink was roughly 115 degrees f. So assuming a temperature delta of 60 degrees, this seems about right.... e.g. 61 degrees cold side + 60 degree delta = 121 degrees on hot side.

So the 2nd device I built uses 4x 12709 peltiers (they pull 6 amps each), and 4x 12706 peltiers (they are pulling 2.5 amps each). I have the 12706 peltiers directly up against the water manifold, and the 12709 peltiers stacked ontop of those to cool the hot side of the 12706. I was assuming that stacking the peltiers like this would allow for me to get a higher temperature delta... allowing me to reach my desired 50 degrees.

I am also using a larger heatsink, and 4x fans to cool the heatsink (attached image below showing heatsink).

I have this running as we speak, and it doesn't seem to be working very well. It has been on for 4 hours and has only cooled the water 6 degrees.... roughly 3 times slower than the first device. The temperature of the water is decreasing very slow, and the heatsinks are roughly 150 degrees f. The manifold is not cold to the touch like my first device is. I am having a hard time imagining this being able to cool the water to 50 degrees.

Am I doing something wrong? Thanks and any help is greatly appreciated!
-Matt


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 Post subject: Re: Improving my peltier device - need to cool water to 50 d
PostPosted: Tue Nov 03, 2015 10:57 am 
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Joined: Sat Nov 06, 2010 11:28 am
Posts: 151
Hello

Sorry for the late reply

The first device I build used 2x 12710 peltiers. I attached an image below. The peltiers were supposed to be 10 amps, but in reality were only pulling 4 amps each. This worked pretty decently, but plateaued to 61 degrees f (ambient air temperature was 78.4 degrees f, and the heat sink was roughly 115 degrees f. So assuming a temperature delta of 60 degrees, this seems about right.... e.g. 61 degrees cold side + 60 degree delta = 121 degrees on hot side.

did the hot side get to 121 F or C ? cos the delta of a TEC is in C and thus your maths looks suspect ?

What TEC's did you buy ? they only uses the specified power under a certain circumstance so they might have been 10 amp ones

So the 2nd device I built uses 4x 12709 peltiers (they pull 6 amps each), and 4x 12706 peltiers (they are pulling 2.5 amps each). I have the 12706 peltiers directly up against the water manifold, and the 12709 peltiers stacked ontop of those to cool the hot side of the 12706. I was assuming that stacking the peltiers like this would allow for me to get a higher temperature delta... allowing me to reach my desired 50 degrees.

This is theoretically true but does not work in practice this is covered in my sticky " everything you've ever wanted to know about TECing"

in reality this would have heart you very badly

I have this running as we speak, and it doesn't seem to be working very well. It has been on for 4 hours and has only cooled the water 6 degrees.... roughly 3 times slower than the first device. The temperature of the water is decreasing very slow, and the heatsinks are roughly 150 degrees f. The manifold is not cold to the touch like my first device is. I am having a hard time imagining this being able to cool the water to 50 degrees.

Simply put to increase cooling you want more Qmax (tooling power) and more efficient hotside cooling water cool the hot side


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