Thermal insulation performance evaluation of liquid helium tank based on insulation of liquid nitrogen cooled shield

Liquid helium (LHe) is a critical and non-renewable resource, but its storage and transportation face challenges such as high evaporation losses and economic costs. The use of the advanced liquid nitrogen cooled shield (LNCS) insulation system to protect LHe is an efficient and economical solution. In this paper, an experimental setup was established to investigate the thermal insulation performance of the LHe tank based on the LNCS insulation system. The transient heat transfer characteristics and heat flux variation through multi-layer insulation (MLI) were analyzed under three conditions: without LNCS, with LNCS, and with intermittent nitrogen venting. Results show that the LNCS system expands the low-temperature region of MLI, reducing heat flux. The maximum temperature difference with LNCS reaches 112 K, and a 14.9 K increase in LNCS temperature leads to a 23.6 % rise in heat flux. The apparent thermal conductivity of MLI increases with the average MLI temperature. The study quantifies MLI thermal conductivity in the LHe region, providing valuable data for insulation design. Economic analysis reveals significant cost savings for LHe with LNCS, with return rates above 74 %, highlighting its potential for efficient and cost-effective LHe storage, also providing reference experience for efficient storage of other cryogenic energy sources.