A thermoelectric thermopile is a device that generates an electrical voltage or potential difference across its terminals when there is a temperature gradient applied across its junctions. It operates based on the principle of the Seebeck effect, which is a phenomenon where a voltage is generated at the junction of two different conductors when there is a temperature difference between the junctions. This voltage arises due to the movement of charge carriers, such as electrons or holes, in response to the temperature gradient.
The basic components of a thermoelectric thermopile include multiple pairs of thermocouples, which are made up of two different types of materials that exhibit the Seebeck effect. Each thermocouple consists of two wires or legs, usually made of different metals or semiconductor materials. When one end of the thermocouple is exposed to a higher temperature (hot junction) and the other end to a lower temperature (cold junction), a voltage difference is generated between the two ends.
The working principle of a thermoelectric thermopile can be summarized as follows:
Temperature Gradient: The device is set up so that one side (the hot side) is exposed to a higher temperature, while the other side (the cold side) is exposed to a lower temperature. This temperature difference creates a gradient across the thermocouples.
Seebeck Effect: At each thermocouple junction, due to the Seebeck effect, a potential difference (voltage) is generated between the two dissimilar materials. This potential difference is directly proportional to the temperature difference across the junction.
Series Connection: The thermocouples are usually connected in series, which means that the voltage generated across each individual thermocouple adds up. This arrangement increases the overall voltage output of the thermopile.
Net Voltage Output: The cumulative effect of the individual thermocouple voltages results in a measurable net voltage output across the terminals of the thermopile. This output voltage can then be used to power electrical devices or be measured as a temperature difference.
It's important to note that while thermoelectric thermopiles can generate a voltage based on temperature differences, their efficiency is relatively low compared to other methods of power generation. However, they find practical applications in situations where a small and portable power source is required, such as in thermoelectric generators for remote sensors, energy harvesting from waste heat, and some niche cooling applications.