液氢储罐多层绝热结构设计优化及传热特性研究

To enhance the storage efficiency of liquid hydrogen and further improve the thermal insulation performance of multilayer insulation structure (MLI), the impact of modifying layer density was investigated, increasing the number of vapor-cooled shields (VCS), and altering the arrangement of VCS on the thermal insulation characteristics of liquid hydrogen storage tanks. The results indicate that, for the insulation structure composed of 60 layers of aluminum foil and 240 layers of dacron net, the optimal insulation performance is achieved when the radiation shield layers are arranged with layer densities of 7, 17, and 25 layers/cm from the cold boundary to the warm boundary. Under this configuration, the variable-density multilayer insulation structure reduces heat leakage by approximately 5.2% compared to the uniform-density design. For a single-stage VCS, the optimal placement is at the 22nd radiation shield layer near the cold boundary, resulting in a 65.6% reduction in heat leakage compared to the absence of VCS. When implementing a two-stage VCS, the series configuration outperforms the parallel arrangement, with the optimal positioning of the inner and outer VCS at the 14th and 34th radiation shield layers, respectively, yielding a 20.9% reduction in heat leakage relative to the single-stage VCS. Additionally, this study proposes replacing the dacron net used as a spacer material near the cold boundary with dry paper, which exhibits a lower thermal conductivity in cryogenic environments, can effectively reduce heat leakage from the insulation structure. Moreover, the lower the interlayer temperature of the original insulation structure, the more pronounced the improvement in its insulation performance.