Transient-state modeling and thermodynamic analysis of self-pressurization liquid hydrogen tank considering effect of vacuum multi-layer insulation coupled with vapor-cooled shield

The transient-state model of self-pressurization of liquid hydrogen tank is constructed. It consists a heat and mass transfer model of fluid domain and a heat conduction model of VMLI (vacuum multi-layer insulation) coupled with VCS (vapor-cooled shield). The vapor consumption factor λ_v, the dormancy extension factor λ_d and the unit factor λ are defined. λ_v is the ratio of vapor consumption with the initial hydrogen mass in tank, and λ_d is the extension of the dormancy with VCS opened relative to that with VCS closed, and λ is the efficiency of VCS shielding heat leakage. The effects of the mass flowrate in VCS, λ_v, dimensionless position of VCS, opening moment of VCS on λ_d and λ are investigated. The results show that, when λ_v and the operating time of VCS are fixed, the best dimensionless position of SVCS (single vapor-cooled shield) and DVCS (double vapor-cooled shield) that maximizes λ_d is 0.622 and (0.333,0.644) respectively. Under condition that the duration time of VCS and λ_v are fixed, for SVCS and DVCS, the best opening moment that maximizes λ_d is observed to be day 23.26 and day 34.84 respectively, and the maximum of λ_d with DVCS is 29.5 % larger than that with SVCS.