Geometric optimization of thermoelectric elements for maximum efficiency and power output

The geometry of n- and p-type thermoelectric elements (TE) in terms of the cross-sectional area and length were optimized to yield either maximum thermal conversion efficiency ηth,max or maximum power output Po,max. The optimization process incorporated temperature-dependent material properties and independent thermal and electrical contact resistances that are a function of the contact area per TE leg. Additionally, ηth,max and Po,max were quantified by simultaneously optimizing the TE geometry and varying the hot-side fluid temperature, cold- and hot-side heat exchanger effective area and heat transfer coefficients using a complete one-dimensional thermal resistance network model. Optimized compared to non-optimized geometries, excluding contact resistances, achieve a maximum 10.4% increase in Po,max and 3.2% increase in ηth,max for conditions studied. Optimized compared to non-optimized geometries, taking into account independent thermal and electrical contact resistances, exhibit a 29% increase in volumetric power density and 12% increase in volumetric efficiency in comparison to non-optimized cases.