Thermo-electric refrigerators (figure 7) due to their high cost and low efficiency are far less commonly used then vapor compression or gas cycle. However they do have their advantages, the adaptability and lack of moving parts/circulating fluid make it ideal for small lightweight applications. As well as applications where leaks of a vapor compression unit would be catastrophic.
Thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice versa. A thermoelectric device creates a voltage when there is a temperature difference between the 2 sides of the device. Thermoelectric refers to 3 separately defined effects; the Seebeck effect, Peltier effect, and Thomson effect. Refrigeration utilizes the Peltier Effect.
A Peltier device consists of a hot side and a cold side where a current is made to flow through a p-n junction between the 2 conductors. Heat may be generated or, in a refrigerators case, removed at the junction.
Common Uses for Thermo-electric Refrigeration:
- Portable coolers
- Airplane Refrigerators (lightweight)
- Cooling electronic components and small instruments.
- Any need requiring an accurate temperature setpoint (accurate to 0.01°C)
- Any need requiring the ability to seamlessly switch between heating and cooling (important for thermal cycling)