Design Improvement of Thermal Elements in Order to Reduce Thermal Stresses in Thermoelectric Modules

摘要

A thermoelectric (TE) module has a temperature gradient on both of its sides while in operation. Such induces significant thermal stresses and deformation which eventually lead to device failure. The study investigates the possible method in improving its life by changing the thermal elements design. It mainly applies mathematical and numerical approaches to solve stresses problems. In order to compare two structures based on stress point of view, it establishes a set of mathematical models for both bonded and sliding contacts in connecting corner legs to the substrate of TE modules. These models are based on previous studies on flip chip assemblies and use structural mechanics for estimating the magnitude of the induced stresses at the thermal element connections. Two different mathematical models are investigated: a mathematical model for a TE module with perfectly bonded contact and a new design of TE module having sliding contact. Results comparison for finite element simulations and theoretical analysis have proven accuracy of the mathematical models. Besides, changing the connection design from a bonded contact to a sliding connect can reduce a significant amount of imposed stresses, forces, and moments thus improving the operational life of TE modules. Although the initial conceptual design has been proven to be effective using both finite element analysis and mathematical modeling, the structural performance of new design are also investigated using an experimental work.