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Fine dust is one of the important factors affecting precision instruments and human health, and the pleated filter media has been widely used in air filtration field. Based on the SEM image of the actual pleated filter media, a microscopic 3D model of the pleated filter media was established and the gas–solid two-phase flow was simulated using OpenFOAM. The results show that OpenFOAM can well simulate the particle deposition on the surface of the fibre filter media and the dendritic structures. The transverse distribution of the amount of deposited particle in the pleated filter media is in the form of two peaks structure, while the longitudinal distributions of the amount of deposited particle in 30° and 60° of the pleated filter media are relatively uniform with multi-peaks structure. The average relative error of the pressure drop between the simulation result and the empirical formula is 3.69%, and the pressure differential decreases first and then increases with the pleated angle, and at a gas velocity of 0.4 m/s, Δ Pmin is around 5 Pa (35° of the pleated angle). Through the above studies, the results could be helpful for the development and design of the pleated filter media.

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The crystalline solid-air in the liquid hydrogen will cause erosion or friction on the elbow, which is directly related to the safety of liquid hydrogen transportation. The CFD-DPM model was used to study the erosion characteristics of solid-air to liquid hydrogen pipelines. Results show that the outer wall of the cryogenic liquid hydrogen elbow has serious erosion in the range of 60–90°, which is different from the general elbow. The erosion rate is linearly positively correlated with the mass flow of solid-air particles, and the erosion rate has a power function relationship with the liquid hydrogen flow rate. The fitted relationship curve can be used to predict the characteristics and range of the elbow erosion. The structure of the liquid hydrogen elbow also has an important influence on the solid-cavity erosion characteristics. The increase of the radius of curvature is conducive to the reduction of the maximum erosion rate, while the average erosion rate undergoes a process of increasing and then decreasing. The radius of curvature is 60 mm, which is the inflection point of the average erosion rate of the 90° elbow. The research results are expected to provide a theoretical basis for the prevention of liquid hydrogen pipeline erosion.

Liquid hydrogen is an important way for hydrogen energy storage and transportation in the future. However, the safety issue should be a concern because it will quickly form a low- temperature, flammable and explosive vapor cloud when liquid hydrogen leaks. A new liquid helium spill experiment method was used to predict the dispersion characteristics of liquid hydrogen in confined space at this work. The concentration cloud and the infrared cloud images near the liquid helium pool were obtained at the same time. Results show it is a safe and reliable way to study the leakage and diffusion characteristics of liquid hydrogen instead of liquid helium. After the liquid helium leaks and diffuses, a white cloud cluster will quickly form, and the vapor cloud cluster has a clear temperature boundary observed by infrared thermal imaging equipment. The concentration decay rate of the helium concentration near the leakage port along the vertical height is less than the concentration decay rate of the horizontal distance, which are 0.098%/mm and 0.118%/mm, respectively. The research results have certain technical guidance for the application and safety protection of liquid hydrogen.