A thermopile is a device that converts heat energy into electrical power through the Seebeck effect, which is a phenomenon where a temperature difference between two dissimilar materials leads to the generation of a voltage. Thermopiles are widely used in various applications, including temperature measurement, energy harvesting, and infrared sensors.
Here's how a thermopile generates electrical power from heat:
Thermocouples: A thermopile consists of multiple thermocouples connected in series or parallel. Each thermocouple is made up of two different types of conductors or semiconductors, usually metals or alloys, that are joined together at two junctions. These materials have different thermoelectric properties, which means they produce a voltage when subjected to a temperature gradient.
Temperature gradient: When one side of the thermopile is exposed to a heat source (high-temperature side) and the other side is kept at a lower temperature (cold side), a temperature gradient is established along the length of the thermocouples.
Seebeck effect: The temperature difference between the two junctions of each thermocouple causes electrons to flow from the hot junction to the cold junction or vice versa, depending on the materials used. This movement of electrons creates a voltage potential across each thermocouple.
Series/Parallel arrangement: The individual voltages generated by each thermocouple are additive when connected in series. In contrast, when connected in parallel, the overall current-carrying capacity is increased, but the voltage remains the same.
Power generation: By connecting multiple thermocouples in series or parallel, the overall voltage and current can be increased, allowing the thermopile to generate a measurable electrical output. The more thermocouples there are in the thermopile, the higher the voltage and power output it can produce.
Load resistance: To extract useful electrical power from the thermopile, it is connected to an external electrical load (a resistor or a device that consumes electricity). The load provides a path for the electrons to flow, converting the voltage generated by the thermocouples into a usable electric current.
It's important to note that thermopiles are typically used to generate relatively low levels of electrical power, and their efficiency depends on the material properties of the thermocouple and the temperature gradient across the device. However, they can be very useful in applications where a steady source of heat is available, such as in gas-powered heating systems, industrial processes, or even in some energy harvesting scenarios where waste heat can be converted into electricity.