Depressurization of CO2 in a pipe: High-resolution pressure and temperature data and comparison with model predictions - supplementary material, 2020

Depressurization data are needed for the validation of thermo- and fluid dynamics models describing transient multiphase flow of CO2 and CO2-rich mixtures, which in turn are needed to shed light on the design and operation of safe and efficient CO2-transport and -injection systems - a crucial part of CO2 capture and storage (CCS). In order to design safe and cost-ecient CO2-transportation systems, accurate transient flow models capturing the occurrence of gas, liquid and solid CO2 are needed. These in turn rely on experimental validation. In this work, we present a new experimental facility designed to capture pressure and temperature during the depressurization of CO2 and CO2-rich mixtures in a tube at high spatial and temporal resolution. Experiments with pure CO2 starting from both gaseous and dense (liquid) states are presented, and a reference experiment with N2 is included. The experimental results for both pressure and temperature are analysed by comparison with predictions by a homogeneous equilibrium model. Emphasis is put on the decompression-wave speed, of particular relevance for running-ductile fracture in CO2-transportation pipelines. We observe good agreement with predicted decompression-wave speeds in the single-phase region, and fair agreement for two-phase flows when the calculations are based on the assumption of equilibrium. However, the observed ‘pressure plateau’, a key factor in the prediction of running-ductile fracture, can be significantly lower than that calculated assuming equilibrium. For further information about ”Depressurization of CO2 in a pipe: High-resolution pressure and temperature data and comparison with model predictions - supplementary material, 2020”, please contact the principal investigator.