Energy conversion performance optimization and strength evaluation of a wearable thermoelectric generator made of a thermoelectric layer on a flexible substrate

Abstract

This paper studies the energy conversion performance and strength of a wearable thermoelectric generator consisting of a thin thermoelectric layer bonded to a flexible substrate. The thermal conductivity, Seebeck coefficient and electrical resistivity used in this paper are calculated from the fundamental formulas of carrier motion as functions of temperature. This gives more accurate calculating results and in line with actual situation. Convective heat transfer between the thermoelectric layer and the environment and the contact thermal resistance between the thermoelectric layer and the human skin are considered. Analytical solutions of power output density and axial stress in thermoelectric layer are derived. It is found that the bending of thermoelectric layer can increase the open-circuit voltage. The power output density increases to a peak value and then decreases with the length of the thermoelectric layer. On the premise of guaranteeing the strength of thermoelectric layer, the optimized length of the thermoelectric layer for obtaining maximum power output density is given.