Thermohydraulic characterization of supercritical and dense-phase CO2 pipeline transportation with impurities

With the increasingly serious problem of global climate change, achieving carbon neutrality and peaking has become a common focus of attention for governments and the scientific community. Carbon Capture, Utilization and Storage (CCUS) technology, as an important means to reduce the concentration of carbon dioxide in the atmosphere, plays a crucial role in achieving this goal. Among the various aspects of CCUS technology, the CO₂ transportation process is particularly critical. However, a unified theoretical standard for pipeline transportation of supercritical- and dense-phase CO₂ has not yet been fully established, which limits the wide application and efficiency improvement of CCUS technology to some extent. To fill this theoretical gap, this study adopted computational fluid dynamics numerical simulation techniques to thoroughly investigate the characteristics of supercritical- and dense-phase CO₂ in long-distance pipeline transportation. Through simulation experiments, this study considered the effects of impurities as well as the inclination of the pipeline. The results show that common impurities such as N₂, O₂, and CH₄ affect the phase equilibrium of CO₂, whereas H₂S does not. In addition, the effects of temperature, pressure, and pipe diameter on the thermohydraulic characteristics of CO₂ pipelines were thoroughly investigated in this study, and an accurate thermohydraulic calculation model was developed on this basis. The effects of four common impurities and six different pipeline inclinations on the temperature and pressure changes along the pipeline were further analyzed. These findings provide valuable reference data for the design and operation of long-distance CO₂ pipelines, help ensure the safety and efficiency of the transportation process, provide important technical support for the implementation of future CCUS projects, and help promote the global transition to a low-carbon economy, contributing to the realization of the dual-carbon goal in science.