液氢容器蒸气冷却屏瞬态传热特性与复合绝热结构设计OA

Reducing the overall heat leakage in liquid hydrogen containers is of great significance for achieving low-loss and high-efficiency storage.Liquid hydrogen containers often employ a composite insulation scheme combining high vacuum,multilayer insulation(MLI),and vapor cooling screen(VCS).Steady-state heat transfer models for composite insulation structures have been developed.However,the transient venting of liquid hydrogen containers causes uneven spatial distribution and time-varying characteristics in the heat transfer of the composite insulation structure.Therefore,a three-dimensional transient CFD model of the MLI/VCS composite insulation structure was constructed to investigate the transient heat transfer law within the insulation layer under intermittent exhaust conditions,and the differences in insulation performance between the parallel and helical arrangements of the VCS exhaust pipes were compared.The results showed that the temperature of VCS decreases rapidly during the exhaust process,after the exhaust,although the temperature of VCS rises,it remains at a relatively low level.The cooling effect of the vented cryogen diffuses slowly within the composite insulation structure,demonstrating good cold storage capacity.After multiple venting cycles,the heat transfer within the composite insulation structure approaches quasi-steady state,and the transient fluctuations in interlayer temperature and heat leakage also stabilize.Compared to passive insulation without venting,the intermittent VCS venting strategy reduces boil-off loss by approximately 29.31%.Furthermore,the helical VCS configuration provides more uniform circumferential cooling,resulting in a lower average VCS temperature than the parallel configuration,which is beneficial for minimizing liquid hydrogen evaporation.