Analysis of the effect of nonuniform surface temperature distribution on the performance of a thermoelectric generator

The present paper analyses the effect of an inhomogeneous surface temperature distribution on the operation of a thermoelectric generator (TEG), experimentally and numerically. In the steady-state measurements, a spatially inhomogeneous temperature distribution is imposed on the colder surface of the TEG. The hotter surface temperature distribution is kept homogeneous. The maximum-to-minimum difference in the TEG cold side surface temperature distribution has been changing between 10 °C and 25 °C during the measurements, while the difference of the area averaged cold surface temperature to the hot side temperature has been varying within the range 70 °C and 150 °C. Tests are also performed with homogeneous cold side temperature distributions. Measurements with the variable and uniform cold side temperatures are compared. The comparison shows that a local surface variation within the considered ranges does not have a noticeable effect on the TEG performance. A finite element method (FEM) based computational model is developed and validated based on the measured data. Using the FEM model, it has been possible to increase the applied temperature inhomogeneity to higher levels beyond those, which were possible in the experiments. The FEM model predicts a deviation at very high temperature inhomogeneity on the cold side, which can be justified with the temperature dependency of the material properties.