Design and Construction of a 75 Watt Electrically Heated BiTe Thermoelectric Generator for Demonstration and Model Validation

Radioisotope thermoelectric generators (RTGs) serve a crucial role providing thermal and electrical energy for long-duration missions often in extreme environments such as the arctic, marine, and outer space biomes. Many current designs still rely on geometries and materials dating back to the 1960s. However, the advent of additive manufacturing presents an opportunity to revolutionize RTG design by allowing for the creation of intricate geometries that optimize heat transfer pathways through the thermoelectric legs. Significant advancements in materials research and engineering since the inception of the RTG offer new possibilities for enhancing device performance through the manipulation of grain morphology and material properties. The Nuclear Battery Initiative at Oak Ridge National Laboratory (ORNL) is focused on innovating in and advancing this field by applying state-of-the-art fabrication and modeling capabilities. These multiphysics computational models couple the heat transfer modes of conduction, convection, and radiation with systems of equations relevant to thermoelectric devices for Seebeck, Thompson, and Joule effects. The predictive capability enables quantification of the electrical response of the thermoelectric generator based on the heat source power input, heat rejection, and the external electrical load on the system. ORNL has designed and constructed two simple electrically heated thermoelectric generators for demonstration and model validation. The functional requirements and design of each are discussed in this paper.