The universal influence of contact resistance on the efficiency of a thermoelectric generator

TL;DR

This study reveals a universal impact of contact resistance on thermoelectric generator efficiency, providing guidelines for minimizing contact resistance to optimize performance across various materials and configurations.

Contribution

It demonstrates a universal influence of contact resistance on efficiency and establishes maximum tolerable contact resistance levels for segmented thermoelectric generators.

Findings

Electrical contact resistance should be less than 30% of total resistance for minimal efficiency loss.

Thermal contact resistance should be less than 20% of total resistance for minimal efficiency loss.

Maximum tolerable contact resistance depends on efficiency gains from segmentation.

Abstract

The influence of electrical and thermal contact resistance on the efficiency of a segmented thermoelectric generator is investigated. We consider 12 different segmented $p$-legs and 12 different segmented $n$-legs, using 8 different $p$-type and 8 different $n$-type thermoelectric materials. For all systems a universal influence of both the electrical and thermal contact resistance is observed on the leg's efficiency, when the systems are analyzed in terms of the contribution of the contact resistance to the total resistance of the leg. The results are compared with the analytical model of Min and Rowe (1992). In order for the efficiency not to decrease more than 20%, the contact electrical resistance should be less than 30% of the total leg resistance for zero thermal contact resistance, while the thermal contact resistance should be less than 20% for zero electrical contact resistance. The universal behavior also allowed the maximum tolerable contact resistance for a segmented system to be found, i.e. the resistance at which a leg of only the high temperature thermoelectric material has the same efficiency as the segmented leg with a contact resistance at the interface. If e.g. segmentation increases the efficiency by 30% then an electrical contact resistance of 30% or a thermal contact resistance of 20% can be tolerated.