Thermoambient Energy - Valvim
Thermoambient Energy Project - Conversion of ambient heat to electrical energy

VHETM - Very High Efficiency Thermoelectric Module

Last updated 09/16/2019

In a thermocouple under a thermal gradient, i.e., with a hot junction and a cold junction, there are 4 electromotive forces as shown in figure 1, (E1, E2, E3 and E4).

Electromotive forces in bimetallic thermocouples

Note: 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. These modules exploit the electromotive force generated by electron diffusion along the thermocouple legs (E3 and E4, figures 1 and 2). This diffusion, however, only happens when the junctions are subjected to a temperature difference.

Conventional thermoelectric module - semiconductor

Unlike traditional thermoelectric modules, the VHETM 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 and E2. However, under normal conditions, they cancel each other out because they have opposite directions and the same intensity. See figure 3.

Electromotive forces in bimetallic thermocouples 3

The innovation in VHETM thermocouples lies in the fact that one of its junctions has an electronic nano device that simulates 0 Kelvin. This is why E1 and E2 behave as if they are under a thermal gradient around 300 Kelvin. Thus, the electromotive force generated at the "hot" junction, even at room temperature, is greater than the electromotive force generated at the "cold" junction, which is under the effect of the "0 Kelvin" simulator. With this innovation, the sum of the two forces (E1 and E2) is nonzero and can then be used externally.

Very High Efficiency Thermoelectric Module

For reasons linked to trademarks and patents, I cannot yet publicize the structure of the "0 Kelvin" simulator used in the cold junction. But I will give details of its design, and construction technique, to the person or institution that becomes my partner. Learn more at: Thermoambient Energy Project.

Author: Valvim M Dutra

This text has been translated from Portuguese. If you find some grammatical error or linguistic incoherence, I shall be grateful if you let me know the location of the mistake so that I can correct it.

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