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Engineering LibreTexts

8: Thermoelectrics

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  • A thermoelectric device is a device which converts a temperature differential to electricity, or vice versa, and it is made from a junction of two different conductors or semiconductors. To understand thermoelectric devices, we need to understand the fundamentals of heat transfer and thermodynamics. This chapter begins by discussing these fundamental ideas. Next, thermoelectric effects and thermoelectric devices are discussed.

    Many common processes heat an object. Rubbing blocks together, for example, heats them by friction. Burning a log converts the chemical energy in the wood to thermal energy, and applying a current to a resistor also heats it up. How can we cool an object? If we supply electricity to a thermoelectric device, one side heats up and the other cools down. We can place the object we want to cool near the cooler side of the thermoelectric device.

    Thermoelectric devices, pyroelectric devices, and thermionic devices all convert energy between a temperature difference and electricity. Pyroelectric devices were discussed in Sec. 3.1. They are made from an insulating material instead of from a junction of conductors or semiconductors. Thermionic devices are discussed in Sec. 10.1, and they involve heating a cathode until electrons evaporate off. Thermoelectric devices, discussed in this chapter, are much more common than pyroelectric devices and thermionic devices due to their efficiency and durability.

    Thumbnail: Illustration of the thermoelectric effect with a simple thermopile made from iron and copper wires. (CC BY-SA .0 International; Cmglee via Wikipedia)