Thermoelectric Peltier Cooler Explained & Initial Testing

By W. Mevan Fernando

Peltier cooling modules are solid-state active heat pumps that transfer heat from one side to the other based on the Peltier effect. A TEC has two plates, the cold and the hot plate. Between those plates are several thermocouples. All those thermocouples are connected together and two wires, the negative and the positive, come out. If voltage is applied to those wires, the cold plate will be cold and the hot plate hot. In our design, the hot plate will be connected to a heat sink so that the heat gets pumped out. If not, the device will not work properly and may break down. In our design, we will use the peltier cooler to create a cool bed made of aluminum to cool down the agarose gel we use as our printing material so that it will cool down faster and maintain its shape as layers are added to the 3D structure. A schematic of a TEC connected to a heat sink is shown below.

 

 

In our design we will use 4 TECs to provide enough cooling for our print bed. The TECs we purchased had a current rating of 6A. We ran the TECs through our 12V, 30A power supply which we use for our printer. The video below shows the tests we ran to see the behavior of the TECs. One of them was connected to a heat sink to observe the difference in temperature readings with and without the heat sink. As expected the temperature of the one connected to the heat sink decreased while the temperature of the rest increased.

Video at this link:
https://www.youtube.com/watch?v=YwmJ70BcB7k

The following picture shows the setup we used to connect the TECs to the aluminum print bed. The placement of the TECs was decided upon the fact that the printing will be done only towards the center of the print bed. Thermal adhesive was used to glue the TECs to the bed.

 

After connecting the TECs to the print bed, they revealed to be faulty. This maybe because we didn’t use a fan to cool down the heat sink once all of them were connected together or because of the poor quality of the TECs we purchased.

References

Picture of schematic:  http://www.tetech.com/FAQ-Technical-Information.html