The following session presents concepts demonstrated through numerical analysis that achieve a maximum temperature difference exceeding 130K with a single-stage device. This is accomplished principally by using distributed transport properties (DTP) with variable TE leg cross-sectional area, but also combines segmentation with alternative thermoelectric materials, including CsBi4Te6 (p-type) combined with magnetically enhanced BiSb (n-type). The novel use of variable area with DTP provides an additional degree of freedom for electrical and thermal resistance as Seebeck coefficients are beneficially varied throughout the leg.
Analyses include the study of devices operating in maximum Coefficient of Performance (COP) and maximum heat pumping (Qc) modes in addition to maximum temperature difference (DT) mode. Validation studies confirmed performance against analytical results using ideal material properties where ZT is kept constant and independent of temperature. Performance was then determined using temperature dependent thermoelectric transport properties.
Simulated results show maximum COPs that are considerably higher for high temperature difference in lower ZT materials, enabling the potential use of lower cost base materials. They also show maximum heat pumping can be increased by up to 100%. Studies also show how devices made with DTP excel over standard devices when operated in off-nominal conditions with substantially higher max COP over a wider range of conditions.
Devices created can provide maximum temperature difference in a single-stage device that was not possible before. A single stage device is simpler than a multi-stage device, thus enabling further applications where this type of steady-state cooling can be used.