Abstract
Investigating the transient behaviour of liquid CO2 decompression is of great importance to ensure the safety of pipeline transportation in carbon capture and storage (CCS) technology. A computational fluid dynamics (CFD) decompression model based on the non-equilibrium phase transition and Span–Wagner equation of state (EoS) was developed to study the effects of actual flowing state within the pipeline on the transient behaviour of liquid CO2 decompression. Then, the CFD model was verified by comparing the simulated results to test data of a large-scale “shock tube” with an inner diameter of 146.36 mm. The results showed that the evaporation coefficient had a significant impact on the transition behaviour of CO2 decompression, while the condensation coefficient made no difference. When the evaporation coefficient was 15 s−1, the CFD-predicted results were in good agreement with the test results. Moreover, the effects of flow velocity on transient behaviour of liquid CO2 decompression were further investigated. It was found that the flow velocity affected the temperature drop of liquid CO2 during decompression, thereby affecting the phase transition of liquid CO2. In addition, the initial flow velocity also showed a significant influence on the transient behaviour of CO2 outside the pipe.
Highlights
Accepted: 18 January 2021Fossil fuels such as coal, oil and natural gas burned by human activities emit a large amount of CO2 into the atmosphere every year
A computational fluid dynamics (CFD) decompression model based on the non-equilibrium phase transition that we have established previously [30] was further developed and used to investigate the effects of the initial flow velocity of CO2 on the decompression behaviour within the pipe and the near-field jet out of the rupture opening
The initial flow velocity has a major impact on the temperature drop
Summary
Fossil fuels such as coal, oil and natural gas burned by human activities emit a large amount of CO2 into the atmosphere every year. Carbon Project (GCP), the total global CO2 emissions in 2018 have reached 36.6 billion tons, which makes the concentration of atmospheric CO2 continue to rise [1]. 2020, the current level of global atmosphere CO2 concentration was recorded at 417.20 ppm (parts per million) [2], which is far higher than the safe boundary of 350 ppm [3]. A high concentration of atmospheric CO2 will aggravate global warming and endanger the balance of natural ecosystems. In order to reduce carbon emissions effectively, the carbon capture and storage (CCS). Technology has been proposed and developed in recent decades.
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