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Peltier Cooling System

Hello all,
Well my electrical questions topic had goten WAY too long, so here is a new topic with a better title. Anyways, I have setup a Peltier cell "sandwich" where there is:

--------------------Heatsink-------------------------------
--------------------Peltier Cell-----------------------------
--------------------Heatsink(coldsink)----------------------

Anyways, it has been effective, cooling form about 75*F day to 65-63*F at night. My goal was below 60, so not bad, because I am still experimenting... It is currently all on top blowing in like so:
Peltier sandwhich
----------------------------(lid)

(don't you love dashes and letters)
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Anyways, I am considering cutting the lid so the cold side can be inside of the tank, hot side outside. I am sure this would be most effective, but I am wondering if there are any other good tweaks so I can save my lid...

Yes, the heatsinks do have fans... The growchamber is equivilent (sp?) to a 55 gallon long tank, but is made from acrylic. With my ultra-fine mist, I get about 59-60*F. Factor in ice bottles, and I'm a happy
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camper.

Thanks a million for any input!!
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Caio!
Lithopsman
 
It's sort of like holding the refrigerator door open to cool down the room...
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You should definitely consider mounting the peltier through the lid. Alternatively, you could mount it in a separate small tank like the setup homer has for ventilation. Then you can make sure the cool air is well-distributed within the grow chamber.

Is caio the same thing as ciao in a different language?
 
Hmmm.  I do have an extra heat sink, ATX powersupply, and fan.  I might just be able to pull off a peltier system for cheap.  Just need to get the peltier, another heatsink(cold side), and I should be ready to go.  Only question is, would my *tropical* species like N. gracilis like to be chilled down to the 50's at night?  At least for the winter?  Choices, choices...
 
Come on, Homer, what kind of talk is that? It sounds to me like a perfect excuse to split your neps into lowland and highland tanks.
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Homer, come on! Please tell me that you are kidding, if not I apologize for assuming... N. gracilis is a lowland tropical, andas such it likes constant warm temperatures. As for highlanders like my setup is for, it seems to be working GREAT!!
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@D. muscipula: The ciao spelled caio was just a spelling mistake... But theoreticly(sp?) it is the same.
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Well, I was thinking of riding the gracilis hard to see what its made of, but I might not since the gracilis has spouted new growth near the base  
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and I'm getting some tropical drosera (Petiolaris) any day now
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 Since they are all going to be in the same tank, it might as well be hospitable to tropcial lowland CP's.  

I don't have room or the motivation at this point in time to construct a new highland tank or peltier system... i'll just be happy with the ventilation system, pygmy terrarium and new plants.
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I am working on something similar for my N. rajah. I am currently using a styro cooler with the guts of a mini cooler's thermoelectric cooler. I can get a temp drop from 73 to 60 degrees. However, I cannot get the system cooler nor can I get the temps above 73 without overheating the cooler. I have thought about putting the thermo on a timing to turn off and on every 30 minutes.

Any ideas on how to warm up the cooler? I have a compact flourescent lamp sitting directly over the opening I have cut on the top. This opening is covered with a clear acrylic sheet.
 
Nick you need a thermostat to be able to do that. In fact if you look around on the net you will probably find a control circuit for the peltier that lets you heat and cool with it.

I have been playing around with peltiers to cool a terrarium I am working on for Golden Mantellas. I find that two Peltiers stacked cool-to-hot, then wired in series is more effective then two stacked or side by side in parrell, and drraws half as much current. Just thought I'd share that tid bit. In my final design I think I will use 8 peltiers assembled into 4 two-stage Peltiers. It should draw right at 10 amps.
 
If anyone is serious about this peltier idea and would like to persue it, I have an engineer friend in Brazil that has worked on the concept for some years now, and would be happy to arrange an email introduction. An economically feasible cooled terrarium would be a godsend to the world. I have been getting component parts for my friend to assist his efforts. There is a LOT of troubleshooting involved.
 
  • #10
I just wanted to share the fact that you can by thermoelectric coolers with thermostats already built for case cooling. They range from $160 to over a thousand depending on BTU ratings and such. The $160 is rated at about 400 BTU.
 
  • #11
what about a fridge with a clear dor, like they sell softdrinks out of? you can put the fridge on its back so the clear door is facing up, and put lights on top of it. you could put it on a timer.
 
  • #12
Here is what I am working on.

Outside of the cooler. The lid is cut open to allow a plastic sheet and a light to fit on the outside:
nep_rajah_cooling_outside.jpg


Inside of cooler. The metal box is the actual insert from the mini fridge. The metal box acts as the coldsink.
nep_rajah_cooling_inside.jpg


Peltier Cell and Heatsink. I currently only have the original heat:eek:ff:cool switch.
nep_rajah_cooling_heatsink.jpg


I am currently getting a drop of about 13°F from ambient temps when the light is off. With the cooler on and the light on, temps rise about 5°F. I have to turn the peltier off to get a rise into the low 80's. I am currently manually manipulating temps.
 
  • #13
Here is a link to a less sophisticated but tried and true method to prechill flowing liquids, like the water in a CP tray.

Flash Cooler

All you would need to do is get a small pump to circulate the water and control it with a thermostat... Instant cool.

Or, you could loop 1/4" polyethylene tubing under the trays or in front of the fan depending on where you wanted the cold.

I am planning to eventually incorporate this into my greenhouse in order to grow Darlingtonia and other cool loving species.

Many days during the summer I will be lucky to get my daytiime temperatures below 90F. This always seems to be fatal to Darlingtonia.
 
  • #14
Hi folks,

Being one CP grower on Brazil - even living on the extreme south where the climate is subtropical - grow some temperate CPs can be nearly impossible. Faced with this problem I had the idea of make one cooled terrarium. This idea was sustained by my big USA friend Tamlin Dawnstar (Very thanks Tamlin!!), as he said on one posted message here. I commented the idea with Marco Craamer, one hollander CP grower and the simply cooled terrarium evoluted to one terrarium with the environment (temperature, humidity, photo period, water level and so on) controlled by means of one microcontroller circuit. We started one discussion group on yahoo groups called terrariumcontroller group. The group only accept members under approval of me and Marco just to limit the number of members to the people really interested on the issue.
If you are interested too, please send one message directly to my email, if possible.

Best regards,

João Roberto

jrgabbardo@cpovo.net
 
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