Strategies for improving the thermal insulation performance of liquid hydrogen tanks: A review of multilayer insulation structure

The promotion of liquid hydrogen (LH₂) is crucial for achieving large-scale hydrogen storage owing to its higher storage density compared to compressed hydrogen and cryogenic compressed hydrogen. Excellent thermal insulation performance can effectively improve storage efficiency and enhance the rapid development of LH₂, with controlling tank interlayer heat leakage being a highly reliable method to enhance thermal insulation performance. The multilayer insulation structure (MLI), as an effective insulation method in interlayer, is known for its exceptional performance in LH₂ storage. This paper aims to provide the first comprehensive review of the MLI development status in recent years. The calculation methods for MLI heat leakage are introduced, and the effects of MLI material, arrangement, and working conditions on the thermal insulation performance are discussed. Methods to improve the efficiency of MLI are also summarized. In addition, since the combination of vapor-cooled shield (VCS) and MLI can significantly enhance the insulation performance of LH₂ tanks, this paper reveals the influence of VCS arrangement position, number, and adding para-to-ortho hydrogen catalytic units on the insulation performance of LH₂ tanks. The shortcomings of the existing studies and the difficulties that need to be addressed in the future are also discussed. This study is essential for developing low heat leakage strategies for LH₂ tanks and improving the efficiency of the insulation structure.