Performance research and optimization of hollow glass microsphere insulation system for large liquid hydrogen sphere

As a high-performance powder insulation material, Hollow Glass Microspheres (HGMs) are suitable for the insulation of large liquid hydrogen spheres. Theoretical calculations and optimization of insulation performance are essential for enabling large-scale applications. This study established a heat transfer model for HGMs to evaluate the insulation performance of three models within a 2000 m³ liquid hydrogen (LH₂) sphere. Additionally, the effect of vapour cooled shield (VCS) on the insulation performance of the jacket was analysed by examing the heat transfer process. Furthermore, a variable-density hollow glass microsphere (VDHGM) insulation structure incorporating VCS was proposed, and its advancements and economic advantages were discussed. Finally, the insulation performance of coated HGMs in LH₂ tanks was evaluated. The results showed that when only HGM insulation was used, the HGM1 model exhibited the lowest heat leakage, which was 336.32 W. The introduction of single VCS can further improve performance over HGM insulation, reducing heat leakage by approximately 57.83%. The use of two VCSs further reduced heat leakage by approximately 67.03%. VDHGMs can combine the insulation characteristics of various models of HGMs while reducing the overall purchase cost HGMs by several tens of thousands of dollars. Placing the coated HGMs at the outer position of the jacket allows for effective radiant heat transfer isolation. In conclusion, HGMs exhibit excellent insulation performance and strong vacuum adaptability. The proposed insulation structure is expected to further enhance insulation efficiency and reduce costs.