Experimental study of cryogenic fluid flow in porous thermal insulation materials

Abstract Porous thermal insulation materials, such as polyurethane foam, glass wool or glass fiber, have been widely used in the field of cryogenic storage and transportation systems. In situations where cracks or holes occur in the package wall layer, the stored cryogenic liquid will leak and penetrate into the porous media. The liquid evaporates and diffuses in the porous media and absorbs a large amount of latent heat of vaporization from the surroundings, which may even cause system damage. Therefore, in order to predict the influence caused by the leakage process on the cryogenic storage and transportation system, it is very important to investigate the fluid dynamics and diffusion characteristics of cryogenic fluid in porous media. In this study, an experimental setup was built based on a typical kind of LNG cargo containment system to explore the cryogenic leakage behavior inside the porous thermal-insulation materials. The transient temperature fields were studied under different inlet conditions. The experimental results indicated that the transient temperature is greatly influenced by the inlet conditions and the properties of the fluids. As the liquid content at the inlet increases, the minimum temperature inside the porous media decreases. The lowest temperature of the hull plate reaches 78 K in 110 s when liquid nitrogen is injected through a 4 mm diameter hole at an inlet pressure of 0.04 MPa and a brittle fracture area of 0.34 m 2 was generated on the hull plate at 30 minutes. The results of this study are helpful in predicting the leakage problem and determining the leakage level that will occur during the operation of the containment system.