Best way to cool the hot side?

[sempaii]

Hi all... First of all, I'm new to the world of TECs and cooling, so maybe I'll be asking dumb questions. I'll try to give you as much information as I can on this post and if there is something I missed I'll be glad to post it later. Hopefully you'll be able to guide me in the right direction. :)

Here's the story: I'm trying to build a cooling system (not to cool a CPU) and I bought the following:
1 x 320W TEC (Model CP1-12726):
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=280163028128
http://new-electronics.gr/peltier/CP1-127_SERIES-PERFORMANCE_SPECIFICATIONS.pdf
2 x heatsink + fan combo: http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=170160068115
1 x 350W PSU: http://www.newegg.com/Product/Product.asp?Item=N82E16817170010

My purpose is to create a insulated box, cut one of the walls, put the peltier with the cool side facing in to cool down the interior. Think of it as a mini-fridge.

To test the TEC I attached one heatsink/fan to each side of the peltier and fed them 12V. I was expecting one cool side and one hot side, and that happened for a moment, but then the hot side got REALLY hot, so the cool side started to heat. :confused:

Then I tried feeding the TEC with only 5V (12V to the fans) and it worked, the fan cooled the hot side and the cold side was cool. :cool:

My guess is that If I wanted to use more of the cooling capacity of the TEC, I would have to use a bigger heatsink/fan or some other method for cooling. I'm trying to be cost-efficient here. I don't want to buy something that doesn't do the job and then have to buy something bigger, but I don't want to buy more than I need. So basically the question is what's the easiest (cheapest) way to dissipate the heat generated by that TEC so it works the way it's supposed to... What would you suggest? :shrug:

Thanks in advance. :D

PS. In case you're curious about what I'm building, I'm a homebrewer and to get the best results it is important to control the temperature while it is fermenting. That's what I want the 'cool box' for. Take a look a this link to see another attempt to solve this problem, but with ice instead of a TEC:
http://suburb.semo.net/jthornton/FermChill.htm
This is more like what I'm trying to build, but instead of a cooler I'll use a custom built insulated box:
http://tinyurl.com/yp5bag

[Scarlet Infidel]

Im surprised you even got it to work at 5v looking at those heatsinks!

If im correct at 5v that unit will produce approx 35w of heat which needs to be cooled by the heatsink on the hot side and the temp difference will make the cold side about 37 degrees cooler than the hot. So if your heatsink had a rating or 1c/w then youd end up with a cold side just below ambient. For this i think those fans would have to be going pretty fast.

At 12v i think you are looking at more like 224w of power on the hot side to cool and a temp difference of about 64 degrees.

These are rough numbers which assume no heat load on the cold side (not strictly true). Also the level of the cooling actually used will affect these numbers because the characteristics of peltiers change as they heat up.

Try looking around for c/w ratings for heatsinks to work out a rough idea of the temperatures to expect without going into complex maths.

[sempaii]

Thanks for the reply, Scarlet. You're right, the cold side was not that cold, just slightly cooler than ambient. :down:

Let me see if I understand how this C/W rating thing works.
Say I'm feeding 12V, and as you say 224w of heat are being generated and delta t = 64°C (BTW, how did you calculate that? :confused: ). If my ambient temp is 30°C and I get my hands on a heatsink with a C/W rating of say 0.15:

The temp on the hot side would be:
224w*0.15 + ambient = 63.6°C

And the cool side would be 64°C cooler, that's -0.4°C. :rolleyes:

That would work great for my purposes, but, are my calculations correct?

Now, how do I find which heatsinks are around that C/W rating? You think maybe I'll need water cooling? :hm:

[TopherTony]

You should shoot NoL a pm, he did a pretty extensive guide on TEC's IIRC.

http://www.overclock.net/peltiers-tec/59153-nols-tec-guide-guide-1-basic.html

[railmeat]

Thanks for the reply, Scarlet. You're right, the cold side was not that cold, just slightly cooler than ambient. :down:

Let me see if I understand how this C/W rating thing works.
Say I'm feeding 12V, and as you say 224w of heat are being generated and delta t = 64°C (BTW, how did you calculate that? :confused: ). If my ambient temp is 30°C and I get my hands on a heatsink with a C/W rating of say 0.15:

The temp on the hot side would be:
224w*0.15 + ambient = 63.6°C

And the cool side would be 64°C cooler, that's -0.4°C. :rolleyes:

That would work great for my purposes, but, are my calculations correct?

Now, how do I find which heatsinks are around that C/W rating? You think maybe I'll need water cooling? :hm:

"You think maybe I'll need water cooling?"

yes water all the way:up: or on extreme air using a thick copper heatsink with a screamer(vantec tornado 80+cfm on it).

as far as power requirements u can google using 2 junk powersupplys and running them in parrell for a 24 volt line to your 320 pelt giving u dam close to 320 watts ...google it.

good luck,post back here i wanna see how u made out.

[littleowl]

There is lots of good info up in the stickies if you have time to read them.
For a 226w tec I would not recomend air at all for it and I don't ever recomend using a pc power supply for a tec. You should do some googling to find where people don't cool there tec the right way! You will get to see lots of fires and stuff.

[Scarlet Infidel]

Theres plenty of info around but it takes a while to find it all.

I think if you were to find a half decent air cooler and put a fairly high cfm fan on it (if you dont mind the noise) then run the pelt at around 7.5v you might get temps around -10 degrees. Ill point you in the direction of the maths required when ive more free time.

[billdavis]

the amount of money plus electricty you will use makes it really worth it to just go phase

[sempaii]

Ill point you in the direction of the maths required when ive more free time.

That would be great, Scarlet. :D

If you get a chance please let me know if the calculations I made look ok. Thanks a lot! ;)

BTW, I found a heatsink with a C/W rating of 0.15. It's the ThermalRight Ultra-120 eXtreme: http://www.silentpcreview.com/article759-page3.html

Any comments on it, anybody?

[sempaii]

the amount of money plus electricty you will use makes it really worth it to just go phase

I'm not really familiar with that form of cooling, but from what I saw in the forum gallery seems too cumbersome and difficult to build (at least for me). I'm looking for something more compact and easy to put together, but I'll look into it as well. Thanks! ;)

[littleowl]

You wouldn't want to build it yourself because it would cost a ton of money,
You would want to have one built for you!

I think what your making would be better made out of a chiller. you could read in the chiller section and ask a few questions some of the chiller guys may even be willing to build you one.

I am a visual person so if you can explain to me what exactly your trying to do. I understand your trying to install a tec inside a cooler to chill what is in it. but you will need a relay to turn the tec on and off and if your traveling with it then how would you power it? I have tons of questions!! :D

[Scarlet Infidel]

Im not sure using a single TEC in this way is the most efficient thing. Ive been speaking to a guy on another forum whos developing a very user friendly peltier calculating program. I wouldnt say its quite ready yet to post here (esp without his permission).

Thats a pretty good cooler, 0.15 c/w is very good. I get my formulas from all over the place (many of them conflict too) but here's (http://www.melcor.com/pdf/Thermoelectric%20Handbook.pdf) one place thats not bad for a read. It also has some equations lower down relating to cooling boxes. I know i have a better page to show you somewhere but im struggling to remember where. Also as people have said, read the stickies too.

[sempaii]

There is lots of good info up in the stickies if you have time to read them.
For a 226w tec I would not recomend air at all for it and I don't ever recomend using a pc power supply for a tec. You should do some googling to find where people don't cool there tec the right way! You will get to see lots of fires and stuff.

I went through the stickies but I'll check them out again. :up:

Why is it that you don't recommend a PC PSU for a TEC? What would be the alternative? I checked that the capacity of the 12V rail was enough to feed the TEC, although when I had only the fans running and then connected the TEC at 12V the fans would seem to slow down... :confused:

I am a visual person so if you can explain to me what exactly your trying to do. I understand your trying to install a tec inside a cooler to chill what is in it. but you will need a relay to turn the tec on and off and if your traveling with it then how would you power it? I have tons of questions!! :D

This pic (http://s174.photobucket.com/albums/w83/mmadia/CoFC/?action=view&current=IMG_0532.jpg) will give you a better idea of what I'm trying to build, not to travel at all... And you're right about the relay. :yepp: I bought a White Rodgers controller (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=270080306125) (close on high) to set the temp I want and keep it there. :cool:

Now I just need a way to cool the TEC!! :D

[PhilippF]

As said before: For your application a TEC is an absolute inefficient way of cooling. You waste huge amounts of electricity. Why didnt you use a simple household fridge? Its perfect for cooling the fermentation bottles, comes completely assembled and is already equipped with a thermostate...

Ok, but you want to go with your TEC solution: First, as almost all before said, you will go nowhere with air cooling if you want to run your TEC on high power. If you reduce the voltage and run on reduced power (which will get you higher energy efficiency), you can try one of the better CPU coolers. But take care the baseplate of the cooler covers ALL of your TEC. If you leave even a 2mm edge not in contact with the cooler, you will get problems.
To be better off you will have to get a water cooling setup, which means: water cooling block, radiator, water pump, reservoir and some hosing. Use only distilled water or distilled water with proper additive.

If you have a look at www.frozencpu.com under "Liquid cooling" you will see a section "TEC cooling". I think you will find anything you need.

On the cold side, I would use one of the little heatsinks you purchased.

But please do some calculations on how much current you will use and how much it will cost you and then perhaps think again about the fridge...

Regards,

Philipp

[littleowl]

I went through the stickies but I'll check them out again. :up:

Why is it that you don't recommend a PC PSU for a TEC? What would be the alternative? I checked that the capacity of the 12V rail was enough to feed the TEC, although when I had only the fans running and then connected the TEC at 12V the fans would seem to slow down... :confused:


For one the AMP rating on a psu is not what you will be getting. That is just what you could get at a peak moment. Also the psu wires are not made for running that many amps through them. They need to be replaced. The most common psu that is used is the meanwell 320w and bigger.


This pic (http://s174.photobucket.com/albums/w83/mmadia/CoFC/?action=view&current=IMG_0532.jpg) will give you a better idea of what I'm trying to build, not to travel at all... And you're right about the relay. :yepp: I bought a White Rodgers controller (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&rd=1&item=270080306125) (close on high) to set the temp I want and keep it there. :cool:

Now I just need a way to cool the TEC!! :D

hehe looks like a kegerator!! :p:
Yeah I think a chiller would work best for that because it is so big.
As for cooling the tec the best way to cool a tec is water and that is the only recommended way to cool a tec, unless it is an 80w or smaller you should never put it on air because of fire hazard!!

[THE JEW (RaVeN)]

You should shoot NoL a pm, he did a pretty extensive guide on TEC's IIRC.

http://www.overclock.net/peltiers-tec/59153-nols-tec-guide-guide-1-basic.html

Does anyone here know what TEC NoL was talking about when he mentioned this?

Peltiers also come in all different sizes. Custom peltiers can be ordered from certain manufacturers, but the general sizes are as follows:

40mm - Quite small, normally under 172 watts
50mm - The best size in my mind, normally no bigger than 320 watts
62mm - These are beasts, they come as large as 720 watts as far as I have personally seen.

I would be very interested in a 720 watt TEC just for the heck of it. If someone knows, that would be awesome. I don't want to PM NoL just yet as I feel he must get a lot of them and I don't want to bother him.................yet ;)

[littleowl]

Does anyone here know what TEC NoL was talking about when he mentioned this?

he was talking about 320-437 watt tec. he is like me on that one, why get a small tec when you can get a big one and under volt it!! he also had an 80w that he played with and that may have been the one he was using but I would guess it was his 226w tec.

NOL made that tec guide when I was working on my first tec setup. :) I remember that very well.

I would be very interested in a 720 watt TEC just for the heck of it. If someone knows, that would be awesome. I don't want to PM NoL just yet as I feel he must get a lot of them and I don't want to bother him.................yet ;)

he don't mind pms!! just send him a message or add him to your AIM :D

[sempaii]

Well... Thanks to all for the replies.

I want to believe that a good heatsink and a big fan will do, and it seems like some people would agree with that. :D

Water cooling sounds interesting and way cooler (pun intended), but the cost is much higher and it seems to me like I'd have many more pieces to attach to the box.

I'm going for something more compact even if it's less efficient. I'm thinking of this as a temporary solution. In a few years, when I move to a house, I'll buy a fridge, install the temperature controller and use that instead. :D

I'll keep you posted on my results. Just don't hold your breath, there's much going on right now and I don't know when I'll have time to build this thing. ;)

One more question: if I wanted to calculate the electricity consumption of the device how should I do it? That's something I would like to do before buying the heatsink, just to make sure that the increment of the first bill won't be enough to buy the water cooling kit. :rolleyes:

Thanks.