Prismatic Spreading-Constriction Expression for the Improvement of Impedance Spectroscopy Models and a More Accurate Determination of the Internal Thermal Contact Resistances of Thermoelectric Modules

Thermoelectric (TE) devices can convertheat to electrical poweror use electrical power to generate a temperature difference. Theircharacterization is essential to develop devices with higher efficiency.Impedance spectroscopy models have been developed in the last fewyears, and it has become a highly advantageous method for TE systemcharacterization. Recently, it has been shown that this techniquecan also be used to determine internal thermal contacts (between theTE legs and the metallic strips that connect them and between themetallic strips and the outer layers). Here, we developed for thefirst time a spreading-constriction expression which does notassume cylindrical geometry. The enhanced model is also used to characterizefour TE devices from different manufacturers, highlighting overestimationsup to 13% when the previous cylindrical approximation is used. A codeis provided in the Supporting Information ready to fit the experimentaldata. This study positions impedance spectroscopy as a powerful toolto detect and monitor issues during manufacturing or operation ofTE devices, which typically occur at the contacts.