Study on passive thermal protection design and influencing factors of cable non-equilibrium heat transfer in confined high-temperature radiative environments

The trend toward high integration and high power of electronic devices poses significant challenges to the safe operation of cables. Conventional cable protective layers are susceptible to thermal degradation and failure under extreme environments, which necessitates research into passive thermal protection designs under non-equilibrium heat transfer conditions. Focusing on the passive thermal protection of cables in a confined high-temperature radiative environment, this study developed a two-dimensional unsteady heat transfer numerical model of the cable "external heat source-protective layer-core material" system. A high-temperature cable test platform was built to validate and refine the model. Through single-factor sensitivity analysis and orthogonal experiments, the influence weights of density, thermal conductivity, specific heat capacity, and internal emissivity on the cable thermal insulation performance were quantitatively determined. The results reveal that thermal conductivity plays a dominant role in thermal control performance when thermal diffusivity is kept constant. An evaluation formula for thermal control performance was further fitted. In addition, a cable temperature over-limit early warning model was developed with thermophysical parameters, their quadratic terms, and interaction terms as independent variables, which can effectively realize temperature prediction at the engineering level. This study clarified the key parameters and optimization principles for passive thermal protection design of cables, and provides a scientific basis and theoretical support for the optimal design of cable thermal protection structures and the development of high-temperature-resistant thermal protection materials for applications in confined extreme high-temperature environments.