Convection
Thermoelectric devices have inherent resistance to electrical flow. As a result of their resistance, Joule heating occurs within the thermoelectric material and some of it flows to the cooled side counteracting a portion of the cooling taking place there. The patented BSST concept is to use the hot side heat transfer fluid to absorb some of the Joule heating and to then transport it away from the thermoelectric device by virtue of its movement. If the hot side heat transfer fluid is air, you can visualize this concept by thinking of “blowing” the heat away toward the hot side. The calculations for how effective this technique is are quite complicated, so there is no easy “factor of 2 better” as there is with thermal isolation. Clearly the more flow that can be directed along or through the thermoelectric device toward the hot side, the better. Tubular or porous thermoelectric pellets such as the one shown here can be used to channel this flow.