Optimization of thermophysical properties of molten salt-based date-occupied composites based on orthogonal tests

Molten salt is an efficient thermal storage material with broad applications in energy storage and transmission. In this paper, a molten salt-based date-occupied composite model was constructed using Na₂CO₃-K₂CO₃ as the base molten salt, combined with high-performance SiO₂ nanoparticles . Based on the molecular dynamics (MD) method and a three-factor, five-level orthogonal experimental design , the effects of temperature, nanoparticle radius, and molten salt ratio on the thermal conductivity and viscosity of the composites were systematically studied. The results showed that the molar percentage of carbonate and the nanoparticle radius were the main factors affecting thermal conductivity , with F test values of 132.6 and 43.07, respectively; temperature had the most significant impact on viscosity. Meanwhile, increasing Na₂CO₃ content significantly enhanced the viscosity of the composites at larger nanoparticle radii. The proposed objective function offers a theoretical foundation for optimizing the balance between thermal conductivity and viscosity. This balance is especially crucial during the periodic heat storage and release process, playing a key role in the development and application of new heat storage materials. • Statistical analysis assessed material type, composition, and temperature on composites' thermophysical properties. • Key factors and interactions affecting thermal conductivity and viscosity of composites were identified. • Nanoscale analysis revealed mechanisms influencing thermophysical properties of the composites. • A novel objective function was proposed to balance thermal conductivity and viscosity in composites.