Comparative Study on Thermodynamic Characteristics of Composite Thermal Insulation Systems With Liquid Methane, Oxygen, and Hydrogen

Composite passive insulation technology has been proved to be an effective method to reduce heat leakage into the cryogenic storage tank. However, the current related research mainly focused on liquid hydrogen (LH₂). The thermophysical properties of different cryogenic liquids and the thermal insulation materials at different temperatures are significantly different, so whether the results related to LH₂ are applicable to other cryogenic liquids remains to be further determined. In fact, the insulation technology of LH₂ itself also needs further study. In this paper, a thermodynamic calculation model of a composite insulation system including hollow glass microspheres (HGMs), multilayer insulation (MLI), and self-evaporating vapor cold shield (VCS) has been established. The accuracy of the calculation model was verified by the experimental results, and a comparative study on thermodynamic characteristics of the composite thermal insulation system with liquid methane, liquid oxygen (LO₂), and LH₂ was carried out. The results show that the heat leakage reduction of the proposed system for liquid methane, LO₂, and LH₂ is 25.6%, 29.7%, and 64.9%, respectively, compared with the traditional SOFI + MLI system (1 × 10⁻³ Pa). The type of liquid and the insulation system structure has a relatively large influence on the VCS optimal position. While for a specific insulation system structure, the insulation material thickness, storage pressure, and hot boundary temperature have a weak influence on the VCS optimal position.