Introduction

The Peltier module is a current-powered module with two sides, one cold and one hot.

Peltier modules are so named because they use thermoelectricity, and more specifically the Peltier effect.

The peltier module can be used in two ways:

  • Peltier effect: electricity can be supplied to the module, which will create a temperature difference between its two plates.
  • Seebeck effect: By applying a temperature difference between the module’s two plates, the module generates a voltage.

What is the purpose of the peltier module?

Peltier modules can be used for many different applications:

Under the peltier effect, it is often used in coolers to produce cold, in air-conditioning systems.

Under the Seebeck effect, the peltier module can produce a voltage thanks to a heat difference. It can therefore be used to light LEDs or any other type of component that doesn’t require much voltage.

How does the peltier module work?

A Peltier module consists of a series of cells.

A Peltier cell can be briefly defined as a ceramic plate. It produces heat by dissipating calories and cold by absorbing them when an electric current is introduced.

Two conductive materials of different natures a and b are connected by two junctions. An electric current I is then imposed on the circuit. This causes heat release Q at one junction and heat absorption at the other.

The Peltier coefficient for material pair a and b is defined as the thermal power P released or absorbed per unit current I. It is expressed in volts.

Why choose a peltier module?

There are several components for cooling objects, including the compressor for cooling refrigerators. Let’s take a look at the advantages of the peltier module over the compressor:

  • Very good cooling power in relation to size
  • High cell strength
  • Withstands shocks and jolts

However, the peltier module also has its drawbacks, which we’ll describe in detail in the next section.

The limits of the peltier module

As you’ve seen, the peltier module looks like magic: it creates voltage with a temperature difference… But in reality, it has its limits.

For it to create voltage, one side must be cold and the other hot.

But as the two sides are glued side by side, what happens is that the peltier module heats up more than it cools down, so the cold part gets hotter and hotter and no longer produces cold.

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

As far as the Seebeck effect is concerned, for tension to occur, there needs to be a heat difference between the two sides. However, as the two faces are glued together, by convection of energy, they will gradually have the same temperature, reducing the temperature difference and thus the voltage produced.
To achieve this, we need to find two sources of heat, one cold and one hot, to maintain the gap between the two plates.

However, the voltage produced will be much less than that needed to maintain the temperature difference. In real life, we use a fan to dissipate heat and keep the cold in, say, a cooler.

Project examples

Despite these significant limitations, the peltier module can be useful in a number of applications. For the Peltier effect, its effectiveness has already been demonstrated, particularly in coolers and air-conditioning systems.

For the Peltier effect, its effectiveness has already been demonstrated, particularly in coolers and air-conditioning systems.

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

As far as electrical components are concerned, there’s an effect that occurs when they’re switched on: the joule effect. This means that in all electronic components, some of the energy 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, in conjunction with a fan.