Dr.Neumann Peltier-Technik

This effect is named after its discoverer, Jean Charles Athanase Peltier (born Feb. 22, 1785 in Ham, Somme; deceased Oct. 27, 1850 in Paris), and is created by an electrical current flow, which under certain conditions, causes a temperature difference between two metallic conductors. The discovery of these thermoelectric effects was made in the first half of the 19th century. It was Thomas Johan Seebeck who observed the following phenomenon named after him (Seebeck effect) in 1822: if a closed conductor loop is formed consisting of two different metallic conductors, and if a temperature difference exists between the resulting two contact points of both materials, then a circular current flows in the conductor loop. The thermocouples known today are examples, which demonstrate this. The opposite effect (creation of a temperature difference by an electrical current flow) was discovered by Peltier in 1834 (Peltier effect).

In order to make the Peltier effect economically useful, two differing metals are no longer used when constructing a Peltier element. In this case, the resulting temperature difference is under 1 K. Instead, one metal is replaced with an n-type semiconductor (the electric conduction is caused by the flow of negatively charged electrons) and the other with a p-type semiconductor (the electric conduction is caused by the flow of positively charged holes). A copper bridge connects the two semiconductor legs. If a direct current is passed through the Peltier element in the illustrated direction, the copper bridge connecting the two elements cools. Both the existing connection bridges, also made of copper, heat up. In other words, a steady heat transfer takes place from the upper copper bridge to the lower copper bridges.

In order to obtain Peltier blocks, which are practical for technical use, the individual Peltier elements are joined together in a meandering pattern. The combined Peltier elements, which now form a Peltier block, are electrically in series and thermally connected in parallel. Now, the Peltier blocks can be connected in series and/or parallel, if large cooling surfaces are required. In order to weigh the advantages and disadvantages, the user must first inform himself about the differences and similarities between conventional compressor units and Peltier coolers. In both cooling systems, heat flow takes place from a cold to a warm reservoir. With compressor systems, the heat transfer is achieved by means of a coolant, which is compacted by the compressor and transported through the system. In the Peltier cooler, the electric current corresponds to the coolant of the compressor, and the direct current voltage source corresponds to the compressor.

Although the Peltier coolers are more expensive than conventional compressor units, there are a multitude of application challenges which can only be solved by using Peltier cooling components. Special emphasis can be given to miniature cooling, for example, which involves only small cooling capacities. But more significance should be given to the fact that Peltier blocks can be controlled electronically, and therefore provide a control precision level that cannot be achieved with compressor cooling. Another advantage of Peltier cooling/heating is that it is easily convertible. Simply by reversing the polarity of the DC voltage, heat can be produced where it was cooling previously, and vice versa. The application possibilities multiply when not only cold, but also heat is to be produced with the smallest possible units, and/or wherever a continuous change between cooling and heating is needed.