Structural optimization of vapor-cooled shields using a three-dimensional heat transfer model for enhancing storage efficiency

The intrinsically low boiling point and small latent heat of vaporization of liquid hydrogen make it highly susceptible to evaporation during storage and transportation. Given the high energy cost of hydrogen production, minimizing evaporation losses is crucial to avoid substantial economic and energy penalties. The vapor-cooled shield (VCS), an advanced thermal insulation component, can significantly enhance the performance of liquid hydrogen tanks when integrated with vacuum multilayer insulation. However, existing prediction models are either limited in accuracy or burdened by excessive computational demands. To address this, this study develops a prediction and structural optimization methodology based on a three-dimensional heat transfer model to enhance VCS performance and storage efficiency. The proposed model explicitly accounts for the temperature gradient within the VCS and its impact on both tank heat leakage and the interlayer temperature distribution of the insulation system. The effects of VCS material, thickness, and coil arrangement on internal and external heat leakage, as well as on effective thermal conductivity, are systematically examined. The influence of VCS placement within the insulation structure is also investigated, leading to an optimization strategy that balances thermal performance with structural mass. The findings demonstrate that for a 50 m 3 liquid hydrogen tank, the optimal VCS configuration consists of an aluminum shield with a thickness of 6 mm, equipped with 6 parallel coils and positioned at 40% of the multilayer insulation structure thickness. This configuration achieves a heat leakage of 26.49 W, which is only 29.09% of that of pure variable-density multilayer insulation (VDMLI). While a double-stage VCS system reduces heat leak by 5.3% compared to a single-stage configuration, it incurs a mass penalty and introduces additional solid-conduction paths. Therefore, the optimized single-stage VCS combined with VDMLI emerges as the most effective insulation strategy for liquid hydrogen tanks. These findings offer an efficient and reliable methodology for the structural design and accurate performance prediction of high-performance VCS, thereby enhancing storage efficiency.