Peltier junctions ?

[n2ize]

Anyone experiment with Peltier (thermoelectric) junctions as cooling/heating energy transfer devices ? I have several large aluminum finned heatsinks that I have used for laser experiments and I was thinking of using them to build a localized cooling chambre using a series of peltier junction devices.

[NQ6U]

I had a 12V cooler that worked with a Peltier junction that rode in my truck with me for two years. It worked, although not as well as a real refrigerator.

[W9WLS]

A lot there depends on just how cool you think you need, the "PJ's" work well where direct contact is made and they do OK in the application like the cooler Carl mentioned .
If I were going to use them for a "cool box" I would insulate the heck out of the box but provide for air flow to remove heat.
Just don't expect "sub-zero" temp's from what's available on the market currently.

[NY3V]

6610


http://en.wikipedia.org/wiki/Heat_pipe

(http://en.wikipedia.org/wiki/Heat_pipehttp://www.youtube.com/watch?v=LU4eynU6R-8)
http://www.youtube.com/watch?v=LU4eynU6R-8

[WØTKX]

http://www.quick-ohm.com/heat_management.html

[TESLA]

http://www.petticoatjunctionnevada.com/images/logo.jpg

[n2ize]

Thanks for some good info. As coolers I don't expect PJ's to be as efficient as conventional refrigeration as they are marginally efficient in comparison to common gas compression. What I am maily interested is in being able to maintain temperature stability on one side of a near perfectly flat substrate. That is heating.cooling depending on ambient temperatuire.

[n2ize]

http://www.petticoatjunctionnevada.com/images/logo.jpg
Lots of curves you bet . Even more when ya gets... ta the junction... Petticoat Junction.

[X-Rated]

http://www.petticoatjunctionnevada.com/images/logo.jpg

http://www.leonardpeltier.net/images/leonard/leonard.jpg

[KG4CGC]

http://www.petticoatjunctionnevada.com/images/logo.jpg
I remember when that was still on TV after being on TV for years.

[X-Rated]

http://www.leonardpeltier.net/images/leonard/leonard.jpg

I guess no one gets this one. :(

[WØTKX]

Meh, I did. What does Leonard have to do with it? :dunno:

[X-Rated]

Meh, I did. What does Leonard have to do with it? :dunno:

Leonard Peltier Junction.

[NY3V]

Leonard Peltier Junction.

Is that near Petticoat Junction? :)

[X-Rated]

Is that near Petticoat Junction? :)

Leonard Peltier Junction is in Kansas. Ft. Leavenworth. Petticoat Junction was somewhere else. Kansas was referred to as "somewhere else" in an episode.

[KA9MOT]

Anyone experiment with Peltier (thermoelectric) junctions as cooling/heating energy transfer devices ? I have several large aluminum finned heatsinks that I have used for laser experiments and I was thinking of using them to build a localized cooling chambre using a series of peltier junction devices.

Funny you mention this.... As an experiment when I was trucking (I wanted to make the Coleman cooler in my truck work better) I sandwiched 6 or 7 (It has been a while and my memory....) Peltier coolers between 2 large heat sinks. The thing got very cold and created drinking water. There was so much condensation that came off of that thing that there was no way to use it in anything but a cooler (To catch the water). The amount of cold air that came off it was impressive though and if you could find some way to get rid of the water......

I still have my cooler experiment out in the garage.... maybe I should go out and get it and hook it up backwards and see if I can heat my house.

There have been some Peltier CPU Coolers but I don't know how that worked out. Probably water issues in the last place you want water.

[n2ize]

There have been some Peltier CPU Coolers but I don't know how that worked out. Probably water issues in the last place you want water.
That is the exact same thing I was thinking. At first I thought it was a great idea, attached to the heatsink and easily powered right from the computers power supply. Then I began to have second thoughts. What happens on the typical hot easy coast summer day with 90% humidity and water starting to condense on the cpu etc. ?

[ab1ga]

That is the exact same thing I was thinking. At first I thought it was a great idea, attached to the heatsink and easily powered right from the computers power supply. Then I began to have second thoughts. What happens on the typical hot easy coast summer day with 90% humidity and water starting to condense on the cpu etc. ?

One of the advantages of Peltier coolers is the ability to regulate the cooling level precisely. To prevent condensation, the surface of the CPU must be above the dew point, which is less than the ambient temperature in most cases. Setting the target temperature to twenty degrees above ambient would provide significant cooling benefit without the risk of condensation.

73,

[KA9MOT]

The water comes from the heatsink. The cooler cools on one side and heats on the other. Reverse polarity and it does the opposite. On mine, I used 2 finned aluminum 8X6X3 inch heatsinks with my Peltier coolers sanwiched between them. This was attached to the outside of the cooler with a fan pulling air off of the cooler heatsink and another pulling air off of the hot side. This cooler was in a big truck with a very good air conditioner and had plenty of airflow around it. I had lot's of water. I estimate around 8 oz per day.

I've still got this cooler. If you'd like I could send you 1 or 2 of the Peltier coolers so you could experiment. I'm keeping my massive heatsinks though. They weigh probably 3 pounds each (I'm guessing).

[n2ize]

One of the advantages of Peltier coolers is the ability to regulate the cooling level precisely. To prevent condensation, the surface of the CPU must be above the dew point, which is less than the ambient temperature in most cases. Setting the target temperature to twenty degrees above ambient would provide significant cooling benefit without the risk of condensation.

73,

Okay that makes perfect sense. Considering that the CPU temp gets pretty high cooling it to within 20 deg or so above ambient would indeed provide adequate cooling, after all we are not trying to chill the CPU just keep it from getting too hot. However, the peltier CPU coolers that I saw for sale were inexpensive and I don't know if they had any mechanism for regulating temperature. However providing a thermostat or temp regulation of one sort or another wouldn't be all that difficult.

[n2ize]

The water comes from the heatsink. The cooler cools on one side and heats on the other. Reverse polarity and it does the opposite. On mine, I used 2 finned aluminum 8X6X3 inch heatsinks with my Peltier coolers sanwiched between them. This was attached to the outside of the cooler with a fan pulling air off of the cooler heatsink and another pulling air off of the hot side. This cooler was in a big truck with a very good air conditioner and had plenty of airflow around it. I had lot's of water. I estimate around 8 oz per day.

I've still got this cooler. If you'd like I could send you 1 or 2 of the Peltier coolers so you could experiment. I'm keeping my massive heatsinks though. They weigh probably 3 pounds each (I'm guessing).
Sure, if its no problem to send them out here I could definitely use them. I'd be glad to reimburse you for the costs. No problem with the heatsinks. I have several heat sinks of various sizes sitting around here.

[ab1ga]

Okay that makes perfect sense. Considering that the CPU temp gets pretty high cooling it to within 20 deg or so above ambient would indeed provide adequate cooling, after all we are not trying to chill the CPU just keep it from getting too hot. However, the peltier CPU coolers that I saw for sale were inexpensive and I don't know if they had any mechanism for regulating temperature. However providing a thermostat or temp regulation of one sort or another wouldn't be all that difficult.

Temperature regulators can get very sophisticated, keeping temperature constant to a fraction of degree, but I don't think you'd need that for a CPU cooler. The lack of a temperature sensor within the Peltier unit is no problem, because it's the temperature at the surface of the heat sink we need to regulate. (I can imagine strong thermal gradients in CPU cooling systems, and heat sink grease isn't perfect.)

You'd want to have a matched sensor pair for best tracking over a wide ambient range, fairly linear in the ambient range. From then a couple of op-amps should do the trick; I think the heart of the circuit is called a window comparator. Since the window isn't fixed, but moves with ambient temperature, you'll have to be clever.

73,

[KA9MOT]

I'll see if Stevie will go out to the garage this weekend and help me find it. It won't take long to tear it apart, and I'll get a couple into the mail to you this week. I am assuming they are still good (No reason they wouldn't be), they haven't been hooked up since 2005 or so. No charge for the shipping because so many from this site have helped me out in the past. Is your info good on your QRZ look-up?

[n2ize]

Temperature regulators can get very sophisticated, keeping temperature constant to a fraction of degree, but I don't think you'd need that for a CPU cooler. The lack of a temperature sensor within the Peltier unit is no problem, because it's the temperature at the surface of the heat sink we need to regulate. (I can imagine strong thermal gradients in CPU cooling systems, and heat sink grease isn't perfect.)

You'd want to have a matched sensor pair for best tracking over a wide ambient range, fairly linear in the ambient range. From then a couple of op-amps should do the trick; I think the heart of the circuit is called a window comparator. Since the window isn't fixed, but moves with ambient temperature, you'll have to be clever.

73,
Yeah, a window comparator would probably do the trick. It's basically 2 op amps (or a dual op amp) and a few diodes. I was browsing around and they even have a full window comparator circuit already on a chip Matter of fact it might make an interesting project since I want to experiment with peltier junctions anyway. I have a few old machines that I can use to test it on

[n2ize]

I'll see if Stevie will go out to the garage this weekend and help me find it. It won't take long to tear it apart, and I'll get a couple into the mail to you this week. I am assuming they are still good (No reason they wouldn't be), they haven't been hooked up since 2005 or so. No charge for the shipping because so many from this site have helped me out in the past. Is your info good on your QRZ look-up?

No problem, take your time. I really appreciate it. They are probably still good. Yes, my location listed on QRZ is still good. Much thanks.

[KA9MOT]

Jeez..... I missed your post! And I forgot about it too! I'll get it dug out tomorrow.

[n2ize]

Jeez..... I missed your post! And I forgot about it too! I'll get it dug out tomorrow.

No problem. Your efforts are much appreciated. Take your time. Do it at your convenience. No hurry.

[KA9MOT]

Hey! We found this contraption today. It was well stashed. I'll pull it apart this weekend and get a couple in the mail to you.

[n2ize]

Hey! We found this contraption today. It was well stashed. I'll pull it apart this weekend and get a couple in the mail to you.
Sounds great. I'll look forward to it. Hope I can one day return the favor and help out with something. Much thanks.