Modeling and implementation of multilayer insulation for small-scale ultrahigh temperature systems

Thermal energy-based portable electrical sources have garnered increasing academic attention because of their high efficiency, high energy density, and exceptional portability. The insulation of heat sources significantly impacts power generation efficiency. However, the fabrication of small-scale multilayer insulation (MLI) is significantly challenging because of the high-temperature environment, material compatibility, and influence of near-field radiation heat transfer. Microfabricated MLI insulators ranging from the micron to millimeter scale were successfully developed in this study. Both the micro- and meso-scale MLI materials exhibited outstanding thermal insulation performances at 1400 K without structural degradation, while retaining 78 and 88% of the radiative heat, respectively. Further optimized micro- and meso-scale MLI materials retained 85 and 93% of thermal radiation, respectively, at temperatures up to 1400 K. The thickness of our fabricated meso-scale MLI material is 24.5-36.8% that of previously reported MLI materials with a comparably low thermal conductivity. Importantly, the designed MLI is not only thinner but also has a considerably lower thermal conductivity. These findings highlight the need for further development of small-scale MLI materials for thermal insulation in thermal energy-based portable power generation systems, such as radioisotope micropower systems and alkalimetal thermal-to-electric converters.