Technology
Thermoelectric devices are heat pumps. The application of electrical power to them causes one side to be cooled while the other is heated. Reversal of the polarity switches the hot and cold sides. Reversing this effect by applying heat and cold to the two sides causes electricity to be generated. Heat and cold are carried away from (or carried to, in the case of power generation) the device by heat exchange fluids flowing through channels that are designed to efficiently transfer heat to and from the thermoelectric surfaces and the fluids.
Five of BSST’s technological innovations are discussed here. Three of them, thermal isolation, convection, and mechanical transport are performance enhancing modifications of the thermodynamic cycle of thermoelectrics. Although these concepts are important to both heating/cooling and to power generation, the explanations below focus on heating and cooling.
A very high level view of these techniques can be seen by examination of the equation for heat flow from the cold side of a typical thermoelectric device:
Thermal isolation provides a means for reducing the last term by reducing ΔT. Convection and mechanical transport attack the middle term by providing a way to move some of the Joule heating away from the cold side.
The other two innovations, high power density, and construction, are practical techniques associated with the design and construction of thermoelectric devices.