Peltier cooler

Anyone know anything about Peltier coolers. A friend of mine wants to cool
12"x15"x30" glass vivarium a maximum of 20-30 degrees farienhieght below
ambient temperature. It's long term for a salamander. A friend of hers got
her a surplus Peltier cooler. Which I installed. It didn't drop the
temperature very much inside the vivarium. After doing some research I don't
think it's powerful enough. As far as I know she doesn't have any specs on
it.
So the questions are:
Is this a good way of cooling in this situation? Got any better suggestions?
Would house insulation sheet foam on 5 sides make an appreciable difference?
My first suggestion was air-condition the room but she doesn't like
air-conditioning. I'm in Hawaii so ambient temperatures are 59-90
farienhieght.
Thanks for any thoughts or suggestions.
Karl
Reply to
Karl Vorwerk
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A little bit, I'm using one to cool my CPU.
You might try this place for research info:
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Probably not the best way. Peltiers only cover a limited area, and you have to come up with some way to remove the waste heat before it leaks back to the cold side. I'm not sure of a better way. Maybe taking a mini-fridge and removing the door and attaching it to one sode of the vivarium?
Sorry I wasn't much help, but hopefully I pointed you to some good info. Todd
Reply to
Todd Rich
Just wondering, what kind of temps your getting and what cpu and is it overclocked? I am watercooling, and enjoy it so much more over air. Easy 16 degrees C cooler, and a whole lot quieter. Are you still using air to move the heat off the sink on the warm side of the pelt?
Reply to
Grady
I'm getting about 55=B0F-60=B0F (12-16=B0C), on a AMD 1600+, not overclock= ed,=20 mainly because my chip/mb combo isn't the best. However I'll be moving=20 to an A64 system designed to overclock in a few months, so I'm working=20 out the kinks in my cooling now.=20
I'm using a Danger Den Maze4-1 water cooling setup to cool the hot side of= =20 the peltier. I've got a heater core that fits 2 120mm fans to dump the=20 heat into the air. I could go a lot cooler with a phase-change setup, but= =20 one of the main reasons I got into watercooling in the first place was to=20 cut down on the noise. I'm also going to be building my own case because=20 even though I've got a full-tower, it routes all my hoses and cable=20 through a 3"x4" hole from the top to the bottom. I like room to work=20 around in, because I do a lot of incremental upgrading. Though the case=20 will be uv-reactive acrylic rather than metal.=20=20
Ob metal content:
I'm planning on machining out a new coldplate out of silver for it's=20 better thermal conductive properties. That might get me an extra couple=20 of degrees C.
Todd
Reply to
Todd Rich
Yes!
Can you define "very much" in F? In general, peltiers will move about the same amount of heat as they use.
So, if the DC adaptor is 20W, it's going to take in 20W of heat, and put it out as 20W at a higher temperature, combined with the 20W of electrical power.
What sort of lighting is being used? Seperating the lighting out into a seperate container, with a fan added will reduce heat gain that way.
Reply to
Ian Stirling
I don't know what I did wrong with my plastic case but it seems that metal shielding is needed. I couldn't keep a monitor within 5' of the box and had problems with the cordless phone on the desk. I'm all metal now.
Grady wrote:
I'm getting about 55°F-60°F (12-16°C), on a AMD 1600+, not overclocked, mainly because my chip/mb combo isn't the best. However I'll be moving to an A64 system designed to overclock in a few months, so I'm working out the kinks in my cooling now.
I'm using a Danger Den Maze4-1 water cooling setup to cool the hot side of the peltier. I've got a heater core that fits 2 120mm fans to dump the heat into the air. I could go a lot cooler with a phase-change setup, but one of the main reasons I got into watercooling in the first place was to cut down on the noise. I'm also going to be building my own case because even though I've got a full-tower, it routes all my hoses and cable through a 3"x4" hole from the top to the bottom. I like room to work around in, because I do a lot of incremental upgrading. Though the case will be uv-reactive acrylic rather than metal.
Ob metal content:
I'm planning on machining out a new coldplate out of silver for it's better thermal conductive properties. That might get me an extra couple of degrees C.
Todd
Reply to
Tom Gardner
I doubt you will find it efficient enough. The industry has chillers for aquariums usually with a titanium coil for water contact. These are conventional refrigeration units with compressors. I don't know how well they would work in a situation chilling air. All I could think of using the solid state modules was setting the terrarium in a tray of water and chilling the water. Seems to me you only need to cool the lower portion of the terrarrium, slamanders tend to stay low.
Reply to
bamboo
they won't cool air at all. the inner coils would get cold and perhaps ice up similar to an old non-selfdefrost freezer .
Reply to
Charles Spitzer
Peltier's are inefficient (you've been told that). They conduct heat as well or better than they pump it (they're metal). You want to have a BIG heatsink/radiator on the hot side and a BIG heatsink/radiator on the cold side. With fans. Insulating the vivarium would be a good idea.
I heard a suggestion to use a mini-fridge -- I second that, but get a real one with a compressor. Or use water cooler, set the water temperature & circulate it through the vivarium (probably closed-cycle through some piping in the soil). Make sure that getting too cold won't hurt the little beasty, and if so put in some failsafes on the temperature regulation.
Reply to
Tim Wescott
Use thermal mass IE water from the fridge. Perhaps the peltier would add additional cooling to it. Betcha a gallon from the fridge a day would work if it isn't in a sunny window. Plan: bottom of vivarium has small stone deep enough that a gallon leaves the top dry. little aquarium pump pumps water from another 1 gallon reservior outside the tank. Can pump it through a small heat exchanger for the peltier. Every day you take a fresh gallon of tap water out of the fridge and change out your external reservior. Insulate the bottom third of the tank to keep water cool. When the evap cooling effect is added, bet it works. Cheep too.
Salamander would seem a boring pet
Tim Wescott wrote:
Reply to
yourname
Peltier coolers will move several watts of heat from the cold side to the hot side but you do need to make sure that you have a big enough cooler to do the job. Insulating the enclosure will decrease the amount of heat getting into the enclosure and this helps allow the device to work well. Look at the car cooler for how much insulation that you need to really get a decent temperature drop. IN addition, you also need to be able to remove the heat and cold from the peltier device or you will be making a cold spot that really doesn't cool the whole enclosure.Water (actually antifreeze) pipes on the cold side have the problem of often freezing water as a single stage cooler can easily hit temps that low if there isn't a lot of heat input to the cooler. Also, removal of the heat from the hot side will increase the efficiency as the coolers work better at low temps than at high temps in addition to the fact that they produce a diffeerential of temp across them according to the current tht is run through them and the amount of heat that is being movrf. I like to run my coolers at about 50-75% of their capacity to keep them at their efficient range. I'll note that you can run several peltier coolers in series as long as they are of the same type device - junction count doesn't care but the individual junction type (peltier devices are made up of a large number of individual pellets of the junction material). This can make the construction of the power supply a lot easier as lower currents can be had which reduces the size of the parts. Basically, insulate well, move the heat quickly and run enough of the devices to move all of the heat you do have to move. If one won't do the job, add more and eventually you will move enough heat to cool to the temps you want. I've made some stacks (cold to hot sides of several devices, each lower in temp of the stack a smaller size) and gotten temps down below -40 with these devices.
-- Why isn't there an Ozone Hole at the NORTH Pole?
Reply to
Bob May
Peltier devices (also known as TEC, thermo-electric coolers, and TEG, thermo-electric generators) are solid state devices that transfer heat (or cold) from one side of the device to the other. Or, they'll produce a voltage in response to a temperature differential. The normal temp differential from the "hot" side to the "cold" side of the device is about 50 degrees Celsius (a LOT more than any pet would like), BUT you still need to move the heat off the "hot" side if you're trying to cool (think heat sink and fan) AND circulate the air on the "cold" side. It is really made for cooling surfaces, I don't know how successful you'll be in cooling air. Why don't you report back if you pursue this?
George
BTW--You supply a DC voltage to the Peltier device to get it to cool/heat and you may need to look up its specs to find out exactly what voltage to supply. Also, Peltier devices tend to be small and pricey.
suggestions?
Reply to
George
Some of the 12v coolers for cars use em for air cooling. Very slow to actually cool anything but work ok at keeping cold something that's already cold. Probably just undersized when used in this application due to cost.
Anyway...because they work based on creating a temperature differential, isn't there an application where the are stacked to reach VERY cold temps? You'd have to pump one hell of a lot of heat out of the final stage but it might be interesting to see just how cold one could get the cold side.
Koz
> >BTW
Reply to
Koz
Just one 15" x 30" pane of 1/8" glass will conduct about 730 watts (4992 BTU/hr) if one side is 30 degF different than the other. That seems like a lot, but I checked my math several times. I used k for glass of 0.96 K/(W*m).
However, air is a pretty good insulator. I think if you could create a "cool region" that is perhaps 6" lower than insulated surroundings, a little depression, then a cold plate at the bottom of that region could cool it by 30 deg. With no turbulence, cooled air would stay in the depression and insulate the region. If the region were 12" square and 6" deep, the heatflow necessary to maintain a gradient of 30 degF from bottom to top of that air volume would only be about 0.25 watt. A Peltier can easily do that. I'm looking at a Peltier 1.6" square that can pump about 35 watts with a coldsurface temp of 40F and a heatsink temp of 80F -- assuming you can keep the warm side of the Peltier that cool.
If you use a small dorm-size fridge, the best way would probably be to have a water heat exhanger comprised of a little pump, a coil in the fridge and plastic water lines to a cold plate in the valley in the vivarium.
Reply to
Don Foreman
The Hagen Life-Glo aperture bulbs direct light well and run cool.
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That will cut down your heat gain a little.
Insulation on five sides will help. With all that area, heat will flow in.
But where the problem is, I'd say, is the capacity of the heat pump, and its interface to the terrarium. A big cold plate well greased to the glass bottom of the aquarium would work, but would cost as much as a mini-fridge new. If you had a piece lying around, it'd help a lot because if you just apply the pump to the glass, you'll just get one cold spot of glass, not much cooling over the area.
But really, such a small heat pump will not cool reliably if your ambient goes from 59 to 90.
--Doug No fancy sig available through Google.
Reply to
DGoncz
There are small cryo-coolers based on stacks of Peltiers that are used down to about 100 kelvin. They're like 5 - 7 stages; each stage needs to have 50% to 100% more area than the last so they look like pagoda roofs. Around 100K sterling coolers start to gain ground for that sort of thing.
Reply to
Tim Wescott
Ok - I fess up - I used a Peltier cooler for my Intel 8080.
It was a 1" square cooling and 1" square heating surface.
Keep in mind that the cold side must contact using heat sink grease (or the like) to the 'work' and the hot side must have the same thermal resistance or lower.
It is best to have an massive sink on the hot side - just to get it out of there.
If the hot side isn't cooled (by drawing it off) - then the P-N junctions (semi-conductor) will heat up and conduction halts. Heat can also kill the p-n junctions.
Mine was a 10 or 20 amp unit - that baby would rock.
I used a massive - Hockey Puck SCR heat sink - size of a shoe box - as the hot sink.
Not logical, but then I couldn't get the heat pipes I wanted at the time.
Martin
Reply to
Martin H. Eastburn
Thanks didn't see that site yet. I thought of the little fridge idea also. She never saw a cheap used one. The other suggestion I thought of was a wine cooler but she didn't want to spend that much. Thanks Karl
Reply to
Karl Vorwerk
My impression was inside the vivarium was approximately room temperature but I'm not sure she took a room air temp to compare. for someone who works in a biotech job she's not very technical. I don't think a light was installed since she didn't give me one to mount on the top. She's trying to find out the wattage. Thanks Karl
Reply to
Karl Vorwerk
I set up the cold heat sink in the vivarium with a 5" fan and the hot side sink on the outside with no fan. Mounted through a 3/8" plywood board for the top of the vivarium. Thanks Karl
Reply to
Karl Vorwerk

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