Thermoelectric generators (TEGs) can convert waste heat into electrical power through Seebeck effect. Increasing temperature gradient across TE device improves the TE power output significantly. However, enhanced thermal gradients lead to high thermal stresses within the TE system and these stresses must be taken into consideration in the design process to develop TE systems with enhanced thermal reliability. Although TE power output has been investigated extensively, thermal reliability studies of TE systems have been limited in literature. This study uniquely investigates the effect of leg topology on the TE performance as well as their thermal reliability to guide the designers in selection of ideal TE leg shapes. The shape of thermoelectric (TE) leg plays a major role on TEGs performance. Conventional rectangular TE leg structure has been the preferred leg topology commonly utilized in TE devices due to its simplicity and high thermoelectric performance. Other leg topologies have also been considered in the literature to quantify their effects on TE performance. This current study investigates the thermal reliability of a several TE leg topologies such as trapezoidal leg, zig-zag leg, butterfly leg, wavy leg, vertical and horizontal cross-shaped leg, X-leg, Y-leg, I-leg according to the construction of each shape. 3-dimensional finite element simulations are presented to quantify the Von Mises thermal stresses of these configurations and compared to conventional rectangular TE leg shape. The accuracy of numerical model is validated against numerical simulations reported previously. Skutterudite was chosen as TE material for all configurations since it is a suitable material for low and intermediate temperature applications. The dimensions of TE leg such as thickness (t), length (L) and the hot surface area of TE legs remained unchanged for all TE leg configurations. The hot and cold surfaces of all models are subjected to fixed temperature of 327 °C and 27 °C, respectively. According to our previous reference study, higher TE power is generated for vertical cross-shaped and butterfly TE leg configurations compared to the other leg topologies. The vertical cross-shaped and butterfly configurations generate 34% and 25% TE power higher than the conventional rectangular TE leg, respectively. In this study the thermal reliability will be evaluated for the aforementioned TE leg configurations to determine the Von Mises stresses. Therefore, this study will investigate for the first time the optimization of various TE leg configurations and assess the thermal stresses under thermal loads along with the TE performance presenting a broad design window to determine ideal TE shapes

Effect of Leg Topologies on Thermal Reliability of Thermoelectric Generators Systems Reliability of Different Leg Topologies in Thermoelectric Generators Systems

Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2021/volume/85543

ASME 2021 International Mechanical Engineering Congress and Exposition (IMECE2021)

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