Thermodynamic optimization of composite insulation system with cold shield for liquid hydrogen zero-boil-off storage

The study of zero-boil-off (ZBO) storage is of great significance for the long-term storage of liquid hydrogen (LH2). Preliminary experimental research on the utilization of cryocooler to achieve ZBO storage has been reported, but the optimization of the total power consumption has barely been considered. This paper will fully consider the working characteristics of the cryocooler, that is, refrigerator efficiency increases with the increase of its working temperature. A novel method to realize the cascade utilization of the cooling power of cryocooler is proposed, which can effectively reduce the total power consumption of ZBO system. A thermodynamic model has been developed to optimize the input power of cryocooler in LH2 ZBO storage with cold shied and multilayer insulation (MLI). Thermal coupling characteristics of cryocooler, cold shield and MLI has been studied at the minimum input power. The mechanism and optimization strategy have been explained quantitatively. By optimizing position and temperature of cold shield, the input power of cryocooler can be reduced by 69.5%-74.4%. In addition, the effects of MLI thickness and boundary temperature on the optimization of the cold shield have been studied. The influence of LH2 pressure in tank on cryocooler input power has also analyzed. (C) 2019 Elsevier Ltd. All rights reserved.