Influence of flash evaporation on safety Characteristics of Liquid Hydrogen Leakage and Diffusion

Abstract

During the storage and transportation of liquid hydrogen, damage of pipeline or sealing failure of valve may cause liquid hydrogen leakage. The cryogenic and combustible hydrogen produced by the leakage are dangerous. Because the storage pressure is higher than atmospheric pressure, flash will occur in leakage accident, resulting in LH2 / H2 two-phase flow at the leakage port. In order to study the effect of flash evaporation on the hydrogen diffusion characteristics, the CFD method is used to simulate the liquid hydrogen leaking and diffusing process at different mass fractions of flash evaporation. The results show that the horizontal distance of combustible cloud diffusion is 15.6m when the liquid hydrogen leaking amount is 60L / min. When 14% liquid hydrogen flashes, the horizontal distance of hydrogen diffusion reaches 24.1m, and with the increase of flash evaporation, the horizontal distance increases significantly. With the increase of flash evaporation, the horizontal distance of cryogenic hazardous zone increased from 6.3m to over 9m. It can be concluded that flash evaporation has adverse influence on the safety after a liquid hydrogen leakage accident, which greatly increases the distance of combustible cloud dispersion and cryogenic hazardous areas.