Thermoelectric Engine: Converting Heat Energy into Electric Energy

Introduction:
A thermoelectric engine is a device that converts heat energy into electric energy through the phenomenon of thermoelectric effect. It consists of two dissimilar electric conductors connected at two junctions maintained at different temperatures. This device utilizes the temperature difference to generate an electric potential difference, which in turn produces an electric current.

Explanation:
The conversion process of a thermoelectric engine can be explained in the following steps:

1. Thermoelectric Effect:
When two dissimilar electric conductors, such as metals or semiconductors, are connected at two junctions and maintained at different temperatures, a temperature gradient is created along the conductors. This temperature gradient leads to the movement of charge carriers (electrons or holes) from the hot junction to the cold junction, resulting in the generation of an electric potential difference.

2. Seebeck Effect:
The electric potential difference generated due to the temperature gradient is known as the Seebeck effect. This effect occurs because the charge carriers in the conductors have different energy levels at different temperatures. As a result, the charge carriers move from the higher energy level (hot junction) to the lower energy level (cold junction), creating a flow of electric current.

3. Electric Energy Generation:
The electric potential difference generated by the thermoelectric effect can be used to power an external circuit and generate electric energy. By connecting the hot junction to the positive terminal and the cold junction to the negative terminal of the circuit, a continuous flow of electric current is established. This current can be utilized to perform various electrical tasks or charge batteries.

4. Efficiency and Applications:
The efficiency of a thermoelectric engine depends on the materials used in the conductors and their temperature difference. The conversion efficiency of thermoelectric engines is typically low compared to other energy conversion devices. However, they have several advantages such as no moving parts, silent operation, and the ability to generate electricity from waste heat.

Conclusion:
In conclusion, a thermoelectric engine converts heat energy into electric energy through the phenomenon of thermoelectric effect. By utilizing the temperature difference between two dissimilar electric conductors, an electric potential difference is generated, which can be used to generate electric current and power external circuits. While the conversion efficiency of thermoelectric engines is relatively low, they offer unique advantages and find applications in waste heat recovery, portable power generation, and niche energy harvesting systems.

It is basically a thermocouple please refer its working