Effect of vapor-cooled shield integrated with thermodynamic venting system on self-pressurization process of liquid hydrogen tank with vacuum multi-layer insulation

To further enhance the thermal insulation performance of liquid hydrogen storage tanks, firstly, the hydrogen gas releases its cooling capacity in the thermodynamic venting system(TVS), and it is introduced into the vapor cooled shield(VCS) in the vacuum multi-layer insulation structure to absorb the heat entering the insulation structure from the outside, thereby forming a cold shield. Secondly, based on this concept, a self-pressurization model for liquid hydrogen storage tanks with vacuum multi-layer insulation structure was developed by using MATLAB. The model incorporates the heat and mass transfer model of fluid domain coupled with the cooling capacity source term of TVS, and the thermal conduction model of multi-layer insulation structure coupled with the cooling capacity source term of VCS. Thirdly, the influences of TVS, VCS, VCST(TVS in series with VCS) on the dormancy of tank during liquid hydrogen or gas hydrogen extraction were investigated. The dormancy was characterized by a dimensionless dormancy extension factor η_d. Finally, the heat leakage flux and the heat absorption of TVS, VCS, and VCST during storage were discussed. The results show that during liquid hydrogen extraction, when VCS or VCST is adopted individually, the maximum η_d is achieved when the dimensionless positions of VCS l_d (it represents the position of VCS in the multi-layer insulation) are 0.400 and 0.489, respectively, corresponding to the maximum η_d of 0.223 7 and 0.308 7. Introducing TVS alongside VCS can increase η_d by 38.00%. However, during gas hydrogen extraction, the improvement in η_d with VCST compared to VCS is negligible, as the added TVS contributes almost no additional benefit.