Abstract:

To further optimize the insulation performance of multi-layer insulation structures applied to liquid hydrogen storage, a sequential quadratic programming algorithm was proposed to optimize the radiation shield spacing of continuous variable density multi-layer insulation coupled with vapor cooled shield (VCS). The effects of the position of the VCS, the quasi-positive transformation within the VCS and the number of VCSs on the optimal radiant screen spacing distribution and adiabatic performance were studied. The results show that the introduction of VCS causes a sudden change in the optimal spacing distribution of radiation shields at the location where the VCS is set, and the heat leakage flux density q_in after optimization can decrease by up to 36.1% compared with that before optimization. Under condition that the optimization is adopted, the introduction of para-to-ortho hydrogen conversion can achieve a maximum decrease of 28.3% in q_in. The increase in the number of VCS significantly reduces the spacing between the innermost radiation shields. When the number of VCS is increased to 2, the minimum q_in decreases by 50.4% compared to the single VCS.

Key words: hydrogen, heat transfer, optimization, vacuum multi-layer insulation, vapor cooled shield, para-to-ortho conversion

摘要：

为进一步优化应用于液氢存储的多层绝热结构的绝热性能，提出采用序列二次规划算法对耦合蒸气冷却屏（VCS）的连续变密度多层绝热辐射屏间距进行优化。研究了蒸气冷却屏位置、蒸气冷却屏内仲正转化以及蒸气冷却屏数量对最优辐射屏间距分布以及绝热性能的影响。结果表明：蒸气冷却屏的引入使多层绝热最优辐射屏间距分布在蒸气冷却屏设置处出现突变，优化后漏热热通量q_in相比于优化前下降幅度最大可达到36.1%；引入仲正转化的条件下优化可使q_in的下降幅度最大达到28.3%；VCS数量的增加使最内层辐射屏间距显著减小，当蒸气冷却屏数量增加到2时，最小q_in相比于单蒸气冷却屏下降50.4%。

关键词: 氢, 传热, 优化, 真空多层绝热, 蒸气冷却屏, 仲正转化