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

Abstract

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 λv, the dormancy extension factor λd and the unit factor λ are defined. λv is the ratio of vapor consumption with the initial hydrogen mass in tank, and λd 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, λv, dimensionless position of VCS, opening moment of VCS on λd and λ are investigated. The results show that, when λv 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 λd is 0.622 and (0.333,0.644) respectively. Under condition that the duration time of VCS and λv are fixed, for SVCS and DVCS, the best opening moment that maximizes λd is observed to be day 23.26 and day 34.84 respectively, and the maximum of λd with DVCS is 29.5 % larger than that with SVCS.