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Peltier Usage

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Piss-Ant

New Member
Joined
Feb 8, 2001
I've been doing quite a bit of research into the Peltier cooling process, and have also been reading a lot of people's horror stories with their attempts to use them as a heat sink. Granted there are quite a bit of success stories, but it doesn't seem as if they are granting far greater cooling capabilities over a normal heatsink.

So my question is: Wouldn't it be more effective to use the peltier device as a case cooler rather than placing it directly in contact with the CPU? If peltiers are most commonly used to chill coolers, I'm sure that it could bring the temperature of your case down to such a degree that it would not only benefit the CPU working with a heatsink.. but also all the other components in your case.

Does this seem like a reasonable assumption? Or has anyone tried this method yet?

Piss-Ant
 

[email protected]

Member
Joined
Jan 18, 2001
Location
East St. Paul, MB, CA
well you'd have to have a peltier of an ungodly wattage to really affect your case temp. Unless your case was reallt insulated maybe... One side of a peltier gets cold, the other gets hot, so you would still have to be cooling the hot side and somehow exhausting the heat out of the case. If you don't cool the hot side well, then the cold side isn't cold at all...

I'm not an expert on peltiers at all though... :)
 

MsNath

Member
Joined
Feb 4, 2001
This is a great point.
Why not cool the whole case?
And yes peltiers are being used in RV fridges and picnic coolers.

The great benefit of following through on such a project is that you are literally taking the heat right out of the case. Where as when it is on the chip your just moving it off the chip and into the surrounding case requiring even more fans to move it out of the case.

By having the hot side of the peltier on the outside of the case you have far less worries about over heating.

Plus you have the over all advantage of cooling everything instead of just the chip.

I think this is a great idea. I’m going to start looking into it feasibility more and would really like to collaborate with anyone else that wants to give this a try.

I think the greatest problems will come if we hit near zero, then we have condensation through out the whole case to worry about. But lets see if we can get something working and worry about condensation if we get the temp to drop that low.
 

TechnoFile

Member
Joined
Jan 9, 2001
Location
SC, USA
I'm intrested in this too.... but it would be difficult to do. If sucessful, it may be possible to ditch all those noisy case fans though. Maybe a dual-peltier setup on the top of the case, with a cooler for the pelts on top of that. The cold air would fall, forcing warmer air to the top and creating a nice little convection zone(maybe even a soft breeze, too). The big question is what size pelt to use? Since my MB temp is 23° compared to the cpu at 42°, I doubt you'd need anything like a 100+watt TEC. Cooling the hot sides could be intresting, too. Would a simple HSF setup be able to cut it, or would we wind up waving to watercool the OUTSIDE of the case too... I am definately intrested in the possibilities this offers(and all the fun).
 

Eriksson

Senior Member
Joined
Dec 17, 2000
Location
Iceland
Good Idea, but not new. However as [email protected] said very hard to do. I could fill you in on lots of details but lets just say that if you like to cool your case, peltiers are not what you are looking for. ;D
 

MsNath

Member
Joined
Feb 4, 2001
Why would this be so hard to do? In fact I would suggest that it might be easier than using a peltier and water cooler inside a case on top of a cpu.

Here's the thing.

The hardest part of cooling a whole case is keeping the cold air in and the hot<or room temp air> out.

Now if you're going after max efficiency this will mean sealing off every nook and cranny and then insulating the whole works.

However, there is the brute force method and that is to apply the biggest peltier available <and from what I have read that might only be about 60X60mm or 2 ¾ x 2 ¾ inches> and say to heck with efficiency.

The brute force option was always problematic when cooling the CPU especially when it came down to what to do with the excess heat.

But when the hot side of a peltier is on the outside of case then a lot of the former problems are no longer a worry. You could put a big *** heat sink on top of the hot side of the case and whatever size of fan you want as well. Water cooling on the out side of a case would be far easier than on the inside. Plus in theory you shouldn't have to worry about keeping the hot side as cool. Who cares if it gets to 80, 90 or 100c so long as the temps are within the operating specs of the peltier you should be ok. This of course is not an option when directly cooling the CPU.

According to one site I was at, a 60mm x 60mm peltier could drop temps down to as low as -150c. and operate at +200c. Even if your losing cooling left and right what's left over should be enough to drop you well below ambient temps.

An introduction and claims of -150c
http://www.hitechtec.com/introduc.htm

The air to air design looks about right

Other products using peltiers
 
OP
P

Piss-Ant

New Member
Joined
Feb 8, 2001
<<Maybe a dual-peltier setup on the top of the case, with a cooler for the pelts on top of that. The cold air would fall, forcing warmer air to the top and creating a nice little convection zone(maybe even a soft breeze, too). >>

I was thinking the same thing too. Even perhaps setting up a dual air flow channel, where there is a divider coming down from the top, seperating the fixed disk bays and CPU side. This way the circulated cold air flows down one channel, and the hot air up and out the other. I don't know if it would be better to place the peltier on the bay side or CPU side. Perhaps with a few case fans to push the current along?

Also, on the similiar topic of thermoelectrics. There are devices called Thermocouples that are able to generate electricity from heat. This works by heating the junction of two dissimiliar metals, producing an electric current. If such a junction came in contact with the hot side of a peltier, or CPU heatsink for that matter, it might be able to generate enough electricty to run its own fan? I'll have to look into exactly how much electricity could be generated through that process tho.

Last but not least... mini-dehumidifiers? Has anyone discovered an efficient reasonably sized dehumidier that could aid in preventing condensation in the case? If only there was a way to drain silica crystals without having to remove them from the case....

Anyway.. hit me up with some ideas or feedback... this sounds real interesting.

Piss-Ant
 

MsNath

Member
Joined
Feb 4, 2001
So I was giving this idea some more thought. I was thinking about the loss of efficiency due to all the holes, cracks, crannies so forth. I began to wonder if even using the brute force method would be able to keep up with the flow of room air into the case. I began to think about sealing all the cracks with silicone, however this would be a messy job and you would never get all the cracks.

Then I thought and I'm sure many of you have thought of this before. "Too bad I can't just stick the whole thing in my fridge." You know find an old fridge take out all the shelves yada yada.

Of course that's not going to work. A fridge is way to big, you would have cut holes in it and then there's that big door that you would have to open every time you wanted to pop in a new disk.

Then it kind hit me. How hard would it be to make a custom peltier fridge designed to hold a case. Its dimensions would be just slightly bigger than your case. It would have a single 1 or 2" hole at the back where all your cables would come out and thus be very easy to seal. The top would have the peltier cooling device generation the airflow.

The front has a couple of possibilities. 1 would be a 2 door set up. A large full door to allow the removal of the case and a smaller door that would be directly in front of the drive bays. A foam seal above and below the smaller door would fit tight up against the case to prevent too much cold from escaping when you opened the drive bay door.

This would work well and it would be very efficient. The design is dirt easy. Just a box slightly bigger than your case. Something like this would definatley work and keep things very cool.

Now there are two ways to go from here. 1 add a thermostat/regulator for the peltier to prevent the temps from going to cold and thus producing condensation. <these are easy to get and can often be bought from the same people who sell the pelts>

Or go sub zero and try to come up with an effective way to keep the condensation down.
 

Eriksson

Senior Member
Joined
Dec 17, 2000
Location
Iceland
Small input on peltiers.
Modern units can reach approx 70c° temp difference under zero heat load (when not transferring any heat) Getting more temp difference means stacking two or more units. This method drastically reduces the amount of head for any given size peltier. This is cuz the unit on the hot side has to transfer the heat load, and the amount of heat produced by the colder one.

If you like to cool your entire comp, and you manage to isolate and seal off your case, you have to transfer all heat produced inside the case via the pelts. This heat is somewhere between 50w to 400w for most pc's. I guess we are looking at 250-300w for high end setup under full use.

If you want to remove.. lets say 250w of heat you will need peltier in the 350-400W range to get any temp difference of interest (10-20c° drop). This means you have to get rid of the 250W+ ca 350W produced within pelts via the heatsink. This means 600W.... I say 8 x Alphas could do that, just to picture the situation, and this huge setup could only drop the inside temp of the case few degrees. Of course moving the psu outside of the case would be better, but still hard.

I am just pointing out that this is hard to do with peltiers, The modern fridge has much better equipment for cooling than this.

Keep thinking guys, you dont invent anything if you stop :)
 

engjohn

Senior Member
Joined
Dec 18, 2000
Location
SoCal
What if you use a water system in reverse? I mean use the pelter to cool the water which runs through a radiator(which gets cool) with a fan blowing the cool air INTO the case?
Maybe this would work??
 

MsNath

Member
Joined
Feb 4, 2001
Is $14.10 US for a 70 wat peltier a good price. Im talking to a guy at HiTECH Technologies, Inc. about this project. He also has 77 wat units and 120 wat units.


Im going to go ahead and give this project a try. He recommended starting with 4 70wat peltiers but he has a minimum order of $100.00 so that would be 7, 70 wat units. which might be more in line with what we really need.

He said the 70 wat units are rated to -37c I never got the spects on the 77 or 120 wat units.

The -150 specs he talks about are on small surface contacts so they don't apply to our project.

I wont be able to start manufacturing the case for 2 weeks though. I have to wait for my old man to start working nights at his steel fabrication job :)
 

dasouthernocer

Registered
Joined
Dec 25, 2000
Uhmmm I believe you are going to have better luck getting 2 custom made waterblocks, 2 radiators, 2 pumps, 2 reserviors and plug those 7 peltiers in between the 2 H2Oblocks and the cold radiator will be extremely cold and will chill the case very well. But why not just spend the money on a used A/C unit and duct it to you're case for a nice below zero case, but you're still dealing with air and air does NOT remove heat anywhere near as good as water does. Which is why most use water+peltiers on thier CPU's. Just my 2 cents.

-dasouthernocer
 

MsNath

Member
Joined
Feb 4, 2001
There are several reasons why I have been shying away from conventional refrigeration set-ups.

First, I don’t like them :) They are big, noisy, require compressors yada yada.

Second, this is a peltier cooling project. Not a conventional cooling project. If we wanted to do things the “easy” way then we would all go out and buy new 1.5 gig chips and not worry about overclocking in the first place.

Third and most important because it has never been done before. There are a lot of people out there saying this can’t be done and it would be easier to do this other ways. But so far no one has actually said, "I did this, I built a cooling case just like you described and it didn’t work." There has only been speculation. My speculation is that this will work and when perfected will produce sub zero temps, be very quiet due to the enclosed and insulated case and not require water cooling. It should also work out much cheaper as well.

So lets find out. Here’s a link to 3 drawings I made for the case.

The drawings include the case which is very large because of my 27” tower has to fit into it.
A simple door for testing purposes which will be modified afterwards when all the testing is done.

And finally the top of the case. You may find this interesting. The top of the case is 2 complete heat sinks 1 bottom cold and one top hot. 20” long by 11 ½” inches wide that fit on the top of the case like a hat. Two banks of fans circulate the heat inside the case one bank blows down one side of the case the other bank sucks up from the other side thus producing a circular air flow around the case. I haven’t decided on how to cool the hot side. I want to try and stick with air cooling. Considering I’ll have a 20” X 11 ½” heat sink with at least 4” high fins I might be able to make this work without water…

Go here to down load my JPG drawings they are over 1 mb each and they are a bit messy. Anyone out there wanna make these look official and run them through your autocad program please feel free.


e-mail me directly if you have any questions
[email protected]

Nothing is copyrighted, nothing is patented everything is prior art. Lets just have fun with this.
 

Eriksson

Senior Member
Joined
Dec 17, 2000
Location
Iceland
MsNath : Keep it up!
It is always nice to see people who dosn't give up even though the odds are against them. It is also nice to see that you take critic under consideration but still keeps fighting. There is always ppl coming in here with some "great" ideas, but many seem to be on the 'chat only' level, and give up easy.

I want to tell you what I think, and of course it is up to you if you consider it or not.

I suggest you try to keep the comps psu out of the cool box. This is the greatest heat source in the system and there is no need to cool it down. Besites this is easy to do.

You need also to consider condens forming both outside and inside your cool box, if you manage to get the temps down to the 5c° level you will get condense.
Good luck.
 

MsNath

Member
Joined
Feb 4, 2001
Thanks for the input.

I totaly agree with the benifits you mentioned in regards to removing the power supply.

Im also concerned with the effects of the cold on the disk drives. I'm worreid that if they get too cold they may be damaged during use.

However, for now I'm going to try and leave the psu in the case.

The reason is that I want to build a cooling unit that will be versitile enough that any CPU case can be put in without any or very few mods to the computer case it self.

I have updated the drawings and added a fourth drawing that shows a key feature of the cap. A 45degree machined surface on each side of the fins where the fans will be mounted. This angle of the fins/fans I believe will help produce a smooth flow of air across the fins and dramaticly improve the circulation effect.


I also belive the angle and position of the fans will help isolate condensation away from the computer. As the air is directed across the back surface of the cooling unit it should condensate on that surface as it travels down and thus trap it on the cooling case surface away from the computer case. The cover of the computer case will be in place on that side of the cooling unit. This as well will produce a tunnel effect moving the air smothly down and providing an addition safe gaurd, preventing the cooling air from making its way into the computer case before the condensation process is finished. as the cool air settles at the bottom it should have released most of its condensation safely on the back wall. The warm side of the computer case will have its cover off thus allowing the up flowing air<which should be much dryer> to pass over the internal parts and thus complete the circulation cycle. Not the best solution to the condensation issue I know but it may be all that is needed.
 

Eriksson

Senior Member
Joined
Dec 17, 2000
Location
Iceland
Small Input:
Condense will form on any part inside your cool box if you let ambient air into it. This is just law of the nature and there is nothing you can do about this. Yes even inside your hdds if they are cold enough.

Condense forms at the very same point the cooling occurs. Air that circulates inside your box must therefore not have due point higher than the case temp.

The only way I can see, to prevent this is not to let any ambient air into your box. If you manage to built air tight box, and you never open it the problem is solved.