In cooling processes that require compactness, robustness and absence of maintenance, Peltier thermoelectric units represent the most suitable solution.
What is a thermoelectric unit?
A thermoelectric unit is a technology that allows you to cool small quantities of material or spaces quickly, using only electricity, obtaining the same effects as a conventional system (e.g. a refrigerator), but without using gas, compressors or moving parts. The thermoelectric modules exploit the so-called Peltier effect: “an electric current flowing between two different metals or semiconductors placed in contact produces a heat transfer”.
On one side, heat absorption and consequent cooling will be obtained, then on the opposite side the heat will be transferred to the surrounding environment.
Peltier cell modules are often found in CPUs, chemical laboratories, even in the operating room. But also on planes or helicopters, where small spaces and vibrations would not allow the installation of gas cooling systems.
In the enclosures, in particular, they are unrivaled for reliability, especially in all those industrial applications where the environment to be cooled is cooled on moving parts.
The thermoelectric module
The heart of the system is the thermoelectric module, often improperly called “cell”, a term that refers to its most basic form, consisting of a single junction between two differently doped semiconductor parts. Each thermoelectric module consists of the union of several joints, connected in series with each other and encapsulated between two radiant surfaces, made of ceramic material.
From the application point of view, thermoelectric units can be defined as static heat pumps, controlled by current. They are reversible, because by reversing the direction of the supply current, they allow us to add heat instead of subtracting it.
The limits of Peltier modules
If the principle is easily understood, however, the pitfalls in application are not few and it is easy to run into serious errors. It is no coincidence that just few producers have systems based on Peltier modules for different powers and many have only tried. Sizing and production processes are not obvious, especially if you do not have the necessary experience.
The first critical aspect is the development of intrinsic heat. The temperature difference between the two contact surfaces is a function of the current that flows through the series of cells, but as the current increases, heat is produced by the Joule effect: it is therefore not possible to act on the current in an unlimited way. The same heat, by conduction, also affects the cold side producing losses of efficacy as well as efficiency: the hot side, in fact, is located a few millimeters from the cold side and also with a correct power supply losses are obtained by conduction, if you do not develops an adequate heat dissipation system.
Dissipation in thermoelectric units
Dissipation on the hot side is the most critical component of the whole system and must be achieved both through careful thermotechnical design and with a high stability of the production process. Factors such as roughness, pressure between surfaces, adhesives and thicknesses must be well defined during the project and kept under control in the production process.
Fandis solutions for cooling small spaces
In over twenty years we have accumulated considerable experience in the design and production of thermoelectric units. The Bordos range by Fandis stands out for its performance and reliability: it is composed of devices powered at 12V, 24V, 48V or 230V, with integrated power supply and powers of 50, 100, 200W.