Thermoelement

A thermoelement is a basic unit used in thermoelectric devices. It typically consists of two dissimilar electrical conductors joined at one or more junctions. When there is a temperature difference between the junctions, a thermoelectric voltage is generated due to the Seebeck effect. The magnitude and polarity depend on the materials and the temperature range involved.

In sensing applications, thermoelements form thermocouples, which measure temperature by producing a voltage proportional to temperature difference. Accurate readings require knowledge of the cold-junction temperature and, often, cold-junction compensation. In power generation and cooling applications, thermoelements are used as active legs in thermoelectric modules, exploiting both the Seebeck and Peltier effects.

Materials and types vary with use. Thermocouple types are standardized (for example, Type K Chromel–Alumel; Type J Iron–Constantan) and are chosen for specific temperature ranges, sensitivities, and durability. Thermoelectric modules used for cooling or power generation rely on semiconductor materials, such as bismuth telluride-based compounds for near-room temperature, and lead telluride or silicon–germanium for higher-temperature operation.

Construction considerations include junction integrity, electrical resistance, and thermal coupling. Elements are packaged in protective sheaths for harsh environments and may be embedded in probes for precision sensing or assembled into cascaded arrays for thermoelectric power generation or cooling. Thermoelements are valued for solid-state operation, lack of moving parts, and versatility across a wide temperature spectrum.