An experimental study on the flow characteristics during the leakage of high pressure CO2 pipelines

Abstract High pressure pipeline transportation is dominant mode for economically transporting large amounts of CO 2 . However, potential leakage is one of the main risks associated with pressurized CO 2 pipeline transportation. Thus, to investigate the leakage behavior of high pressure CO 2 and to de-risk such transportations, a new laboratory scale experimental setup (total length of 14.85 m and the inner diameter of 15 mm) was constructed. Leakage experiments for pure CO 2 and CO 2 mixtures containing various N 2 concentrations were carried out for different initial phase states (supercritical, liquid and gaseous respectively). The pressure and temperature characteristics and phase transitions of high pressure CO 2 were then studied following pipeline leakage through small diameter nozzles. The results show that a minimum temperature occurs during the leakage process of various initial phase states; while the temperature characteristics of supercritical and gaseous CO 2 leakage were rather different from that of liquid CO 2 leakage. Impacts of impurity (N 2 ), initial inner pressure and nozzle sizes on the leakage behavior were investigated, and two minimum temperature lines, based on N 2 concentrations and initial inner pressures were obtained, respectively. These findings will ascertain that the pipeline is operated above the ductile-brittle transition temperature.