Numerical analysis on the thermal behavior of a segmented thermoelectric generator

A mathematical model was established to analyze the heat transfer and thermal stress behavior of a segmented thermoelectric generator (STEG). Temperature gradient-induced thermal stress was studied with non-uniform steady heat flux (including Gaussian heat flux and parabolic heat flux), uniform heat flux, and transient heat flux applied to the surface of the hot end, respectively. The results showed that the heat fluxes applied to the hot end lead to uneven temperature distribution on the whole surface of the thermoelectric generator. Thermal stress in the horizontal direction is the major cause of fatigue damage and failures of STEG. When the heat concentration ratio increases, the horizontal temperature uneven distribution will also increase. The thermal stress on the hot end varied significantly reaching the maximum value as high as 16.3 GPa. In addition, the transient heat stress in the system gives rise to periodic stress fluctuations up to 0.6 GPa, which can seriously affect the life cycle of the system.