In a thermocouple under a thermal gradient, that is, with a hot junction and a cold junction, there are 4 electromotive forces as shown in figure 1, (E1
If material B (in blue) is a P-type semiconductor, the electromotive force E4
will have the opposite direction.
Traditional thermoelectric modules, type TEG (Thermoelectric Generator fig. 2), are constructed with P-type semiconductors and N-type semiconductors, forming several series interconnected thermocouples. According to the manufacturers, these modules exploit the electromotive force generated by electron diffusion along the thermocouple legs
, figures 1 and 2). This diffusion, however, only happens when the junctions are subjected to a temperature difference.
Unlike traditional thermoelectric modules, the HETM exploits the electromotive force generated at the junctions of the thermocouples and not in their legs. Electrons excited thermally (above 0 Kelvin) tend to invade border regions that have lower electron density. Therefore, when we join two dissimilar metals, the electrons of the "stronger" (higher energy) material invade the boundary of the "weaker" material thus establishing two electromotive forces, E1
. However, under normal conditions (with temperature T1
= temperature T2
), they cancel out because they have the same intensity and electrically opposite directions. See figure 3.
The innovation in MTAE thermocouples lies in the fact that one of its junctions has an electronic nanodevice that simulates a negative temperature. With this, E1
behave as if they are under a thermal gradient. Thus, the electromotive force generated at the "hot" junction, even at room temperature, is greater than the electromotive force generated at the "cold" junction (special junction) that is under the effect of the negative temperature nanoelectronic simulator. With this innovation, the summation of the two forces (E1
) is different from zero and can be used externally.
For reasons connected to trademarks and patents, I still cannot make public the structure of the negative temperature simulator, installed in the special junctions of the thermocouples. But I will give details of its design, and construction technique, to the person or institution that will become my partner. Learn more about the possible applications of this new technology at: Thermoambient Energy Project