Peltierefektiä

Peltierefektiä, also known as the Peltier effect, is a thermoelectric phenomenon where electric current passing through the junction of two dissimilar conductors causes a temperature change at that junction. Discovered by Jean Charles Athanase Peltier in 1834, this effect is the inverse of the Seebeck effect, which generates a voltage when there is a temperature difference between two conductors.

When an electric current flows from one material to another at their junction, heat is either absorbed or released. If heat is absorbed, the junction becomes cooler, leading to a cooling effect. Conversely, if heat is released, the junction becomes warmer, resulting in a heating effect. The direction of heat transfer depends on the direction of the current flow and the specific properties of the two materials involved.

The magnitude of the Peltier effect is quantified by the Peltier coefficient, which relates the heat absorbed or released per unit of current. Materials with larger Peltier coefficients are more effective for thermoelectric applications. Common materials used include semiconductors like bismuth telluride, lead telluride, and silicon-germanium alloys, chosen for their ability to efficiently transfer heat and conduct electricity.

The Peltier effect has found practical applications in various devices. Thermoelectric coolers (TECs), often called Peltier modules, utilize this effect to create solid-state refrigeration. These modules are used in portable coolers, electronic cooling systems, and precise temperature control devices. While generally less efficient than traditional vapor-compression refrigeration, Peltier coolers offer advantages such as compactness, reliability, and the absence of moving parts.