Design and evaluation of heat exchangers for cooling thermoelectricdevices using additive manufacturing

Thermoelectric modules is a relatively new technology for air conditioning systems en abled by solid state semiconductor base, with major challenges in implementation such as efficiency and high implementation costs. This thesis focuses on the design and manufactureof heat exchangers (HXs)generated using additive manufacturing (AM) that take advantage of the use of free form geometries impossible to manufacture using conventional technologies. Specifically, tryply periodic minimal surface (TPMS) based structures, were tested. For the assessment, diverse gyroid designs with stretched axes were compared against a standard (not stretched) design and a traditional extruded flat fins heat exchanger. Computational fluid dy namics (CFD) simulations and experimental testing were conducted using a custom designed wind tunnel to characterize the temperature drop for these designs. Experimental data suggest that the charactersic high surface area-to-volume ratio of standard gyroids provides a limited performance compared to the stretched configuration. A stretched 4-row gyroid demonstrated the best temperature gradient of 9.21◦C, while the regular gyroid and the stretched 1-row gyroid performed the worst, with gradients of 6.44◦C and 6.05◦C, respectively. However, the convective heat transfer coefficient for the stretched 4-row gyroid was 188.41 W/m2 · K, lower than that of the extruded flat fins design, which was 197.18 W/m2 · K. This indicates that, although the stretched 4-row gyroid design exhibited the most efficient heat absorption, resulting in a significant improvement in the thermoelectric assembly’s efficiency, it still has room for optimization to enhance its convective efficiency. Such improvements could fur ther boost the overall performance of thermoelectric modules. This underscores the potential of optimized complex geometries to significantly enhance both the thermal and overall effi ciency of thermoelectric systems and opens the possibilities to see additive manufactured heat exchangers as feasible for enhancing thermoelectric modules for air conditioning systems.