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