Study on self-pressurization liquid hydrogen tank with multi-layer insulation considering effect of thermodynamic vent system integrated with vapor-cooled shield based on transient-state modeling

A composite system in which the thermodynamic vent system (TVS) is integrated with vapor-cooled shield (VCS) embedded within the multi-layer insulation (MLI) of liquid hydrogen tank is proposed, to improve the insulation performance of tank, and it is denoted as TV-VCS. A transient-state model of self-pressurization of tank with the composite system is constructed. The dormancy extension factor ηd is defined, which is the relative extension of dormancy with TVS, VCS or TV-VCS compared with that without these configurations. The effects of VCS location (lDP) and start moment (ts) of TVS, VCS, or TV-VCS on ηd and the temporal variations of thermodynamic parameters in tank are investigated. It is found that, with liquid venting, at lDP of 0.400 and 0.489, the adoption of TV-VCS increases ηd by 35.18 % and 41.25 % respectively, compared with VCS alone. However, with gas venting, the increase in ηd with TVS-VCS adopted compared to VCS is very small, demonstrating that integrating TVS offers negligible enhancement over VCS performance. When only TVS is utilized to vent liquid or gas, ηd increases with the delay of ts, but ηd almost shows a decreasing trend, under condition of VCS or TV-VCS venting gas or liquid, indicating that VCS dominates in TV-VCS.