The Peltier Effect: Solid-State Cooling Through Electric Current
The Peltier effect creates a temperature difference when current flows through a junction of dissimilar materials, enabling small solid-state coolers with no moving parts.
The Peltier effect, discovered in 1834 by Jean Charles Athanase Peltier, describes how direct current flowing through a junction of two dissimilar conductors or semiconductors causes one side to absorb heat (cool) and the other to release it. Devices using this effect — thermoelectric coolers (TECs) — are compact, silent, and have no moving parts. TECs are used for CPU spot cooling, laboratory instruments, portable beverage coolers, and precision temperature control in laser diodes and CCDs. However, their coefficient of performance (COP) is poor — typically 0.3–0.6 compared to 3–5 for Cooling Technologies: Six Fundamental Approaches. This limits them to low heat-load applications where the advantages of solid-state operation (no refrigerant, no compressor, precise control) outweigh the efficiency penalty. The Peltier effect is the reverse of the Seebeck effect (generating voltage from a temperature difference), and both are aspects of thermoelectric phenomena governed by the material's Seebeck coefficient, electrical conductivity, and thermal conductivity.