Progress on the leakage and diffusion characteristics of CO2 pipelines

CO 2 pipeline transportation is important for carbon capture, utilization and storage (CCUS), and its leakage behavior involves scientific issues such as pressure wave propagation, phase changes, jet expansion, gas diffusion and soil infiltration. Research on CO 2 pipeline leakage and diffusion characteristics is important for pipeline design optimization and emergency measures. In this paper, research on leakage and diffusion in CO 2 pipelines is reviewed for two scenarios: overhead and buried pipelines. The effects of factors such as the overhead pipeline aperture, CO 2 gas impurities, and leakage direction on the phase state, pressure response, and temperature distribution parameters in the pipeline are investigated following leakage events. The applicability of equation of state and multiphase flow models in numerical simulations is analyzed. For buried pipelines, the experimental diameters are mostly less than 100 mm. Studies have focused on the changes in the soil temperature field near the leakage port and the growth characteristics of the dry ice layer and frozen soil layer. Future research should consider industrial-scale experiments, leakage characteristics in complex terrains, low-temperature affected zones, leakage characteristics of irregular cracks, and related issues.