Second(improved) version.

Дата на публикуване: Sep 22, 2010 1:34:23 PM

To solve the problem with insufficient cooling it's possible to do follow steps :

• • Use air only from the aquarium, not from outside.

  • Decrease C/W of the outer heat sink.

  • Increase the contact area of the inner heat sink.

  • Use push-pull air flow system.

I did all of them.

So the new design was little bit different.There was no air coming from outside, but I use only the air in the vivarium.This way, when I bring the temperature down with 1C it will be kept in the volume not discarded outside.So next time when this air is sucked in to the inner heat sink, the air was already cooled down by 1C.

Next I added another 2 TECs of same type.Also I use them in serial connected to 13.5V.I add another inner heat sink, same as the first one.

The biggest improvement was done in to the outer heat sink.The first heat sink that I used was this :

The C/W of this one, even when I use a fan to blow over it was about 0.5C/W.This lead to very high outer heat sink temperature and to high inner heat sink temperature -> poor cooling.

The new one was shorter but with more ribs.Even I have 2 additional TECs the temperature wasn't increase above 38C.

This is the back side of the heat sink, already drilled to attach the inner heat sinks.

In process of mounting the 2 additional TECs to the heat sink.I used a thermal conductivity grease for lower thermal resistance.

This is the final mounting with attached back plate.I used this black soft foam on top of the heat sinks to redirect all the air in to the heat sinks not above them.I also use it to isolate the base of the heatsinks and to prevent suction of air outside of the aquarium.

Another very important step is making better air duct.I used 3mm foam material that I can cut easily with office knife.

Here it is...

Next : with two fans.

And all at one place :

With this set up I was able to reach 10C temperature on the output on the system when the input was 28C which is more than I need.For 5 min it drops the temperature with 3C.

On the outer side there is a 120mm fan to cool down the outer heat sink.