Thermoelectric phenomena
arises out of the intercoupled electrical and thermal currents in a material as illustrated in this animation:
TXL uses thermoelements from the bismuth telluride family of thermoelectric materials. These materials provide the highest known conversion efficiencies in the temperature range of 0 degrees C to +200 degrees C. The n-type and p-type thermoelements are doped so as to provide well matched thermoelectric properties of thermopower, electrical conductivity and thermal conductivity. A two-element generator is constructed using an n-type thermoelectric element (or thermoelement)in electrical series and thermal parallel with a p-type thermoelement.
The electrical connections at the top and bottom of the thermoelements are metallic conductors, generally copper. In order to give mechanical support, a white ceramic top made out of alumina is often used on the top and bottom sides of a module. Each thermoelement generates a relatively low voltage per degree of temperature difference. For the thermoelements in TXL's TEG modules, the generated voltage (or thermopower, S) per thermoelement is approximately 215 microvolts per degree C. In order to obtain higher voltages, it is common to connect many pairs of thermoelements in electrical series as illustrated in this 254 element "topless" module, where a single n-p thermocouple is highlighted in red.
