TABLE OF CONTENTS When an electrical current I is passed through two dissimilar thermoelectric materials (denoted by A and B in Figure 2.25, usually metal or semiconductor alloys), one heats up while the other grows colder. Referred to as the Peltier effect, it forms the basis for thermoelectric refrigeration [Ioffe 1957; Goldsmid 1960].
A principal virtue of thermoelectric chillers is that they are solid state devices with no moving parts and no fluids. They accept DC power input, and can be temperature controlled with great precision. The niche applications for thermoelectric devices are miniaturized cooling loads, unlike conventional mechanical chillers. They are commonly used in military, aerospace, consumer product and medical instrument applications, among others. The dimensions of just the thermoelectric module itself are typically 2.5 2.5 0.5 cm, and some commercial units are as small as 0.4 0.4 0.2 cm. A complete commercial thermoelectric chiller package may occupy only around 300 500 cm 3 of space.
Typically, commercial thermoelectrics comprise semiconductors, most commonly bismuth telluride. The semiconductor material is doped to produce an excess of electrons in one element ( n-type), and a dearth of electrons in the other element ( p-type). Electrical power input drives electrons through the device.
At the cold end, electrons absorb heat as they move from a low energy level in the p-type semiconductor to a higher energy level in the n-type element. At the hot side, electrons...
