Mechanical aspects of structural optimization in a Bi-Te thermoelectric module for power generation

The thermal stress and strain occurring on a Bi-Te thermoelectric module subjected to variable thermal conditions were estimated based on three-dimensional elastic-plastic finite element method (FEM) analysis. The analysis showed that mechanical integrity of the interface between a Bi-Te thermoelement and electrodes of At and Mo coatings formed by atmospheric plasma spraying was significantly reduced and that shear strain rose to 0.6 similar to 1.1% in the vicinity of the interface. Furthermore, to estimate the sensitivity of configurational parameters of the module to the thermal strain, statistical sensitivity analysis based on the design of experiment (DoE) and response surface method (RSM) was conducted. The statistical analysis revealed that the thickness of electrode coatings of At and Mo affected the thermal strain and that the thinner At coating and the thicker Mo coating reduced the thermal strain. In this study, a thermal fatigue test machine was newly developed with a view to verifying these analytical studies.