page_title: Thermoelectric cooling
section_title: Operating principle
hierarchical_section_title: Thermoelectric cooling / Operating principle
caption_attribution_description: English: Schematic of a Peltier device. On top and bottom insulating heat spreaders are used and assumed to be connected to heat and cold reservoirs, respectively. They are shown semi-transparent. P- and n-type thermoelectric materials are stacked electrically in series and thermally in parallel. Depending on whether a current source or a resistive device is connected to the electrical connections, this can work as a Peltier element or a thermoelectric generator.
context_page_description: Thermoelectric cooling uses the Peltier effect to create a heat flux at the junction of two different types of materials. A Peltier cooler, heater, or thermoelectric heat pump is a solid-state active heat pump which transfers heat from one side of the device to the other, with consumption of electrical energy, depending on the direction of the current. Such an instrument is also called a Peltier device, Peltier heat pump, solid state refrigerator, or thermoelectric cooler. It can be used either for heating or for cooling, although in practice the main application is cooling. It can also be used as a temperature controller that either heats or cools.
  This technology is far less commonly applied to refrigeration than vapor-compression refrigeration is. The primary advantages of a Peltier cooler compared to a vapor-compression refrigerator are its lack of moving parts or circulating liquid, very long life, invulnerability to leaks, small size, and flexible shape. Its main disadvantages are high cost for a given cooling capacity and poor power efficiency. Many researchers and companies are trying to develop Peltier coolers that are cheap and efficient.
context_section_description: Thermoelectric coolers operate by the Peltier effect (which also goes by the more general name thermoelectric effect). The device has two sides, and when a DC electric current flows through the device, it brings heat from one side to the other, so that one side gets cooler while the other gets hotter. The "hot" side is attached to a heat sink so that it remains at ambient temperature, while the cool side goes below room temperature. In special applications, multiple coolers can be cascaded together for lower temperature, but overall efficiency drops significantly.
caption: Peltier element schematic. Thermoelectric legs are thermally in parallel and electrically in series.
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