A new model for predicting characteristics of the near-field leakage in high-pressure CO2 pipelines

The safe transportation of carbon dioxide (CO 2 ) is crucial to the successful implementation of Carbon Capture, Utilization, and Storage (CCUS) projects. Accidental leaks in pipelines can pose significant risks to this process. Understanding the characteristics of near-field leakage is essential for accurately predicting CO 2 diffusion patterns and conducting effective risk assessments. This paper presents a compressible multiphase flow model based on non-equilibrium phase transitions. Utilizing this model, the characteristics of under-expanded jets resulting from high-pressure CO 2 pipeline leakage are investigated in this study. The shock wave structures of the Mach disk and jet boundary layer are examined. Furthermore, the effects of various initial pressures, initial temperatures and leakage sizes on the pressure, fluid velocity, temperature, and Mach number in the near field are analyzed. Lastly, the paper proposes predictive formulas for the position, diameter, and boundary layer thickness of the Mach disk based on simulation results. A comparison of the predicted values with experimental data shows that these formulas can accurately predict the characteristic dimensions of the normal shock wave, with a maximum error rate of 5.5%.