# optimize peltier element cooling

I am currently playing around with this Thermoelectric Peltier Cooler Setup:

I have read that it's possible to cool these elements down to more than -20°. However, I got the elements for cooling an aluminum pipe, so I glued both onto the pipe to cool it down.

Its already cooling them down, but clearly not that much as I expected (Just around 0°).

My question is: how can I get more cooling\heating performance from the peliters?

A few comments and observations: -

A single TEC1-12706 peltier thermoelectric cooler can only cool effectively when the thing that it is attached to (the aluminium pipe) isn't conducting ambient heat from the surrounding environment back to the cooler at too high a level.

For instance the TEC1-12706 is rated about 50 watts and let us assume that all this power is converted to the cooling process. Let's say the aluminium pipe has a thermal resistance of 1 degC per watt i.e. if 1 watt of heat power were pushed into the pipe it would rise in temperature by 1 degC.

Or, put it another way, if 50 watts of heat power were extracted from the pipe it would cool by 50 degC. This would cool the pipe down to -25 degC in an ambient of +25 degC.

However, if the pipe has fluid flowing through it at ambient temperature then it won't cool down to -25 degC or even close because that fluid is imparting heat to the pipe and that means you need a bigger and more powerful peltier to extract the power due to the pipes basic thermal resistance AND the power that needs to be taken to cool the fluid.

Given that a Peltier cooler is probably around 15% efficient you have to consider that the heat power you can extract from an object is significantly less than 50 watts.

• Thanks about the ~15% efficiency, I always wondered about that. Just curios where did that figure come from? (One of the reasons I follow stack exchange: You still learn even at old age :-) Commented Jan 10, 2018 at 12:27
• @oldfart I got the figure from here: en.wikipedia.org/wiki/Thermoelectric_cooling Commented Jan 10, 2018 at 12:30
• Not only that but if the pipe has any significant length it will absorb heat from the environment. The temperature it settles at will be dictated by the balance of what the peltier removes vs how much heat the pipe can grab and conduct to the peltier site. That is even before you run anything through the pipe. Commented Jan 10, 2018 at 14:41
• @Trevor_G - you been changing your login name? I mentioned that in para 1 although I never went into detail! Commented Jan 10, 2018 at 14:59
• @Andyaka yup I just thought it needed more emphasis. Yes I changed my name, saw another Trevor asking a question so decided it might be prudent. Commented Jan 10, 2018 at 15:40

If you want the cold side of the peltier to get colder, you need better cooling on the hot side.

• And insulation around the cold side to stop it just warming up as fast as it cools.
– user16324
Commented Jan 10, 2018 at 13:37

I have used Peltier elements in on-board Chip testing but just like you I never got the temperature down very far.
The temperature you can get depends on the amount of energy entering your system and the amount of energy your Peltier element manages to pump out. Don't forget that using the Peltier element itself adds energy.
To control the first you might have to use insulation to prevent outside heat from coming in (If possible).
For the second you should (as mentioned by Colin__s) make the temperature difference across your Peltier as big as possible.

Maybe somebody will reply with a better answer e.g. some formula about how much energy transfer you can get from a Peltier element.
For that it would help if you can give us an idea of the amount of energy entering your 'system'?