Peltier Air Cooling Question

[MjrStryker]

I recently took apart a portable car refrigerator and found that it was powered by a 12V peltier block. I'd like to try and use it to see if I can get some extra cooling out of my air cooling setup. Now from what I've read high wattage TECs require some precautions against condensation but it seems like a lot of hassle to go through just to see if this TEC works or not so I have a few questions for those more knowledgeable in this subject than I.

1) How long can I run a small Peltier without serious risk of damage due to condensation? Is it safe to power it up for a few minutes at a time?

2) Seeing as the nature of a Peltier is to use a heatsink to absorb the heat from the hot side, is it safe to run power through a Peltier without a heatsink attached or will this cause heat damage to the Peltier?

3) Is a 1/8" copper cold plate sufficient to help distribute the processors temperature evenly over the surface or is a thicker plate really required for any performance gain to be noticed?

 

[Gyrfalcon]

Thicker plates are better, and you need to cool the hotside or you will burn out the pelt. For condensation to form you have to get the cold side below ambient temps. Also for pelt cooling generally water will work beter at keeping the heat load resonable. Finally remeber that a pelt cannot transfer heat if it has no power so it has to be on if the computer is and they can draw massive amounts of power through them.

I would recomend taking a tour of the extreme cooling section to get some more information on TEC cooling.

 

[MjrStryker]

I made a run through the extreme cooling section a few minutes ago. For some reason I wasn't expecting Peltiers to be considered "extreme cooling" but they do appear to be able to dissipate a large amount of heat, although inefficiently.

I understand that thicker plates are better, but what's the minimum I need to safely run the Peltier? I've heard 1/4" or 3/8" is about the maximum with copper to notice any performance gain.

Ah, so if I plug it in without a heatsink to test it I'm likely to overheat and fry it? I'll keep that in mind. I do intend to have a separate 12V source for the Peltier as I'm not sure what Wattage it's rated at and don't have an ammeter that's likely to survive the amperage I'm expecting it to draw.

Thanks for the input, it's greatly appreciated.

 

[Impu|se]

You obviously have no clue so either start reading or throw all that stuff away, youre gonna hurt your computer or yourself.

 

[ghost6303]

your more likely to hurt your computer then hurt yourself. but yea you could seriously fuck up your system if you dont know what your doing. and it sounds like you dont even know cooling 101 so if you have a junk computer to test on, then go nuts, but dont put this on anything you want to keep. read the forums long and hard before you do anything. pelt kits you buy are complicated enough, let alone trying to use one you salvaged without knowing any numbers on it.

 

[MjrStryker]

I have the general idea of how the Peltier works and how to use it to cool my CPU, but there were just a few specific questions I wanted answered that I couldn't find answers to in the forums. And yes, I intend to try this thing out on an old Pentium Pro before it comes near anything valuable. Lol.

For example, the idea I'm playing with is to place a copper plate flush against the CPU, then the Peltier flush against that, then a copper heatsink and fan assembly against that. I'm pretty sure this isn't one of those monster 230Watt Peltiers like you can get from DangerDen. In fact, I think it's only around 50-100Watts. As it should draw about 4-8 Amps though it will get its own 1U server power supply rated at 150Watts. I've already got an adapter wired up to let me power up the PSU with a switch.

I got one of my questions answered so far, but I'd still like to know if a 1/8" copper cold plate will be sufficient or should I try to find something closer to 1/4". I gave up trying to risk running it without insulation for a minute or so for testing so I already ordered a neoprene kit with silicone and dielectric gel from DD.

 

[cerebrex]

I have the general idea of how the Peltier works and how to use it to cool my CPU, but there were just a few specific questions I wanted answered that I couldn't find answers to in the forums. And yes, I intend to try this thing out on an old Pentium Pro before it comes near anything valuable. Lol.

For example, the idea I'm playing with is to place a copper plate flush against the CPU, then the Peltier flush against that, then a copper heatsink and fan assembly against that. I'm pretty sure this isn't one of those monster 230Watt Peltiers like you can get from DangerDen. In fact, I think it's only around 50-100Watts. As it should draw about 4-8 Amps though it will get its own 1U server power supply rated at 150Watts. I've already got an adapter wired up to let me power up the PSU with a switch.

I got one of my questions answered so far, but I'd still like to know if a 1/8" copper cold plate will be sufficient or should I try to find something closer to 1/4". I gave up trying to risk running it without insulation for a minute or so for testing so I already ordered a neoprene kit with silicone and dielectric gel from DD.

Your peltier has to match your processor's joule output. TEC Cooling is no magic shortcut to success, everything that makes your computer cool better is: a) a bitch b) expensive, and c) more effort than you thought. I've had experience with TEC's and I can tell you if you put a 50 watt TEC on any computer quicker than that pentium pro, it's going to overpower the unit, and burn it up - and then your processor will overheat. TEC's take a lot of knowledge and trial and error. I click on this thread originally because I just had to see how someone was going to air cool a peltier setup. You might want to look into water cooling first, get aquainted with it, and then use that knowledge to cool a TEC, and move on from there. Oh, and TEC's draw a HELL of a lot of power... like light dimming power... prepare yourself.

Here is my TEC water chiller water cooled system - It planed out at -2c - this was a pic taken as it cycled down:

one of the most basic things you have to recognize is this isn't a heat sink, or a water block - it's not a one way street - removing heat, it's fighting it. Your TEC plate is cooling against your processor, and your processor is heating against your TEC...if the tec can't hang with the processor, it will overheat it - and poof -> $$$. My sincere suggestion would be to pass right over TEC and go to a cascade system... they are far less complicated and you get much better results for much less power consumption and the same insulation work.

 

[ghost6303]

My sincere suggestion would be to pass right over TEC and go to a cascade system... they are far less complicated and you get much better results for much less power consumption and the same insulation work.

although thats not incorect, you have to take into consideration of cost- a ghetto salvaged cheap little TEC vs a several hundred if not thousand dollar phase system, plus the hundreds of hours it takes to build. this is a little simpler

I'm pretty sure this isn't one of those monster 230Watt Peltiers like you can get from DangerDen. In fact, I think it's only around 50-100Watts. As it should draw about 4-8 Amps though it will get its own 1U server power supply rated at 150Watts. I've already got an adapter wired up to let me power up the PSU with a switch.

already a problem here. that 150w power supply- is that total output power? because you are only going to get around 50-100w max on the 12v rail which is what you need. or even worse the 12v rails are split up and only have say 30w on each. they generaly dont use massive power consuming 226w+ TECs to cool a beer can. its probably around 50-100w like you say, but i dont think this power supply you have will be able to keep it going for long.

 

[MjrStryker]

although thats not incorect, you have to take into consideration of cost- a ghetto salvaged cheap little TEC vs a several hundred if not thousand dollar phase system, plus the hundreds of hours it takes to build. this is a little simpler

Ghetto is a good way of describing it. The reason I'm using a Pentium Pro to tinker with is so that any mistakes I make won't be costing me any cash. I've got lots of processors and mobos around 200MHz to goof off with.

I'd be in total bliss if I could afford a cascade system.

already a problem here. that 150w power supply- is that total output power? because you are only going to get around 50-100w max on the 12v rail which is what you need. or even worse the 12v rails are split up and only have say 30w on each. they generaly dont use massive power consuming 226w+ TECs to cool a beer can. its probably around 50-100w like you say, but i dont think this power supply you have will be able to keep it going for long.

Well I considered the requirements of the TEC when picking this supply. It may not be rated for much but its entire output is on a 20pin mobo connection and a single 12V rail. The 12V rail is rated for 8Amps which I'm pretty sure is the most my TEC is going to draw. I know that cheaper PSU's don't always output what they say they will though, so I'll take your suggestion and see if I have any other cheap PSUs laying around with more power....300Watts might do it if the 12V Amperage is at least 10Amps right?

Something else to note. There is a strange device attached to the ground wire of the TEC and originally in the cooler it was pressed against the cold plate. I'm assuming this is something for thermal control probably to prevent the TEC from getting too cold or hot. Not sure which. Any ideas on how I could identify it? I don't have a picture at the moment but I'll post one when I do.

 

[Demon_of_The_Fall]

That A64 4000+ in your sig, Probably 100watts at full load right ?

You're going to want like a 150watt peltier to even bother trying to get good temps in that case.

And if you're trying to cool the hot side of a 150watt peltier you're going to want a hard core water cooling kit.

So give up.

 

[MjrStryker]

That A64 4000+ in your sig, Probably 100watts at full load right ?

You're going to want like a 150watt peltier to even bother trying to get good temps in that case.

And if you're trying to cool the hot side of a 150watt peltier you're going to want a hard core water cooling kit.

So give up.

My questions were not about whether I should or not, and this TEC's never touching my 4000+ anyway, though I appreciate the suggestion.

I still have not gotten a definitive answer as to whether a 1/8" copper coldplate is going to be sufficient to distribute temperatures. One poster has stated that thicker is better, but it still doesn't quite answer that question. The other two questions have been answered.

 

[Arcygenical]

The 1/8" plate should be fine, I wouldn't worry.

Have a multimeter? Hook it up in series with your pelt to measure it's current draw, from that we can figure out voltages.

Also, post pics

 

[cerebrex]

My questions were not about whether I should or not, and this TEC's never touching my 4000+ anyway, though I appreciate the suggestion.

I still have not gotten a definitive answer as to whether a 1/8" copper coldplate is going to be sufficient to distribute temperatures. One poster has stated that thicker is better, but it still doesn't quite answer that question. The other two questions have been answered.

you seem to be ignornig the fact that even if you get the right TEC you don't have the ability to power it, or to cool it, why are you so concerned?

 

[cerebrex]

although thats not incorect, you have to take into consideration of cost- a ghetto salvaged cheap little TEC vs a several hundred if not thousand dollar phase system, plus the hundreds of hours it takes to build. this is a little simpler

I think it depends on your skills, and abilities. I suppose to just took into consideration that whoever is going to be trying this already has a good knowledge of compressors/evaporators, etc. I mean, I can take a mini fridge I paid 50 bucks for and turn it into a beast of a phase change system... you couldn't even get a decent air cooler for that price... but most people wouldn't be able to do that though, so I retort. With the right skills skipping TEC all together would be the right decision.

 

[MjrStryker]

The 1/8" plate should be fine, I wouldn't worry.

Have a multimeter? Hook it up in series with your pelt to measure it's current draw, from that we can figure out voltages.

Also, post pics

That's the type of definitive answer I was looking for. I have a multimeter but it's a dinky pocket one and I don't think it could handle having 4 Amps run through it which is the minimum I expect this TEC to draw at 12Volts.

I think it depends on your skills, and abilities. I suppose to just took into consideration that whoever is going to be trying this already has a good knowledge of compressors/evaporators, etc. I mean, I can take a mini fridge I paid 50 bucks for and turn it into a beast of a phase change system... you couldn't even get a decent air cooler for that price... but most people wouldn't be able to do that though, so I retort. With the right skills skipping TEC all together would be the right decision.

Another good reason why I don't want to drop much cash into playing with this TEC.

---------EDIT-------

It's a bit blurry, but ghere's a pic of the unidentified device attached to my TEC's ground wire. Can anyone tell me what this is exactly? I believe it to be some sort of thermal control or limiter.

and here is the TEC

 

[synaps3]

I would guess its some sort of resistor that varies the amount of current the pelt can draw with temperature. I would remove it and hook up the pelt directly.

 

[MjrStryker]

I think I will do that then. I don't really want to leave some unidentified bit of random hardware attached to my circuit.

 

[Gyrfalcon]

when you run it, make sure you have the master power switch near by. I have seen a TEC burn out and catch fire so be ready to kill all power and grab the fire extinguisher

 

[MjrStryker]

when you run it, make sure you have the master power switch near by. I have seen a TEC burn out and catch fire so be ready to kill all power and grab the fire extinguisher

This is sounding more and more fun with each passing moment. I think safety glasses will be a must for this project. May even test it outside first using an emergency battery with 110 VAC outlet. The computer will be made of otherwise unused and obsolete parts anyway. Thank you for the warning though, I never knew they could catch fire. Would've been a nasty surprise indoors.