The Peltier module is a module powered by a current and has two sides, one cold and one hot.
Peltier modules are so named because they use thermoelectricity and more precisely the Peltier effect.

The peltier module can be used in two ways:

  • Peltier effect: We can bring electricity to it and it will create a temperature difference between each side of the module.
  • Seebeck effect: By applying a temperature difference between each side of the module, it will produce a current.

What is the peltier module used for?

The peltier module can be used for many different applications:

The module with peltier effect, is often used in coolers to produce cold or in air conditioners.

The peltier module used with the Seebeck effect can produce a voltage thanks to a heat difference of each side of the module. It can be used to light leds or any other type of components that do not require much current.

How does the peltier module work?

A Peltier module consists of a series of cells.

A Peltier effect cell can be defined as a ceramic plate. This one makes heat by dissipating calories and cold by absorbing them when electric current is introduced.

Two conductive materials of different natures X and W are connected by two junctions. An electric current is then imposed on the circuit.

This results in a heat release at one junction and a heat absorption at the other junction.

The Peltier coefficient relative to the couple of materials X and W is defined as the thermal power P released or absorbed by unit of current intensity I. It is expressed in volts.

Why choose a peltier module?

There are several components to cool objects, including the compressor that allows to cool a refrigerator. We will see the advantages of the peltier module compared to the compressor:

  • Very good cooling power in relation to the size of the unit
  • The good resistance of the cells
  • Withstands shocks and jolts

Nevertheless, the peltier module has also disadvantages, which we will detail in the following section.

The limits of the peltier module

As you have seen, the peltier module seems magical, it allows to create a voltage with a temperature difference… But in reality it has its limits.

To create a current, one side must be cold and the other has to be hot.

Because the two sides are glued side by side, what happens is that the peltier module will heat more than cool and therefore the cold part will become hotter and hotter and therefore will not produce cold anymore.

That’s why in a portable cooler you will always see a fan to evacuate the hot air produced by the hot side and thus limit this effect.

Regarding the Seebeck effect, for generating a tension, there must be a heat difference between the two faces. However, as the two sides are glued together, by convection of energy, they will have the same temperature and therefore reduce the temperature difference and reduce the tension produced.
For this we need to find two sources, one cold and one hot that will keep the gap between the two plates.

However, the voltage produced will be much less than that needed to keep the temperature difference. In real life, a fan is used to dissipate heat and keep the cold in a cooler for example.

Project examples

In spite of these important limits, the peltier module can be useful in several cases. For the Peltier effect, its efficiency has already been demonstrated, especially in coolers and air conditioners.

For the Seebeck effect, the peltier module can be used to capture cold or hot heat that would otherwise be lost. An example of a project would be to stick a Peltier module against the wall of your house in winter. The walls would be warm because you are heating your house and the outside would be cold because of the winter. This could produce an electrical voltage to light up some of your outdoor light or Christmas lights.

As far as electrical components are concerned, there is an effect that occurs when they are powered up: the joule effect. In all electronic components there is a part of the energy which is transformed into heat. A peltier module could be used to recover some of this energy.
Finally, the peltier module is widely used to cool microprocessors, accompanied by a fan.