Depressurization of CO2 in pipes: Analysis of experiments and non-equilibrium flashing flow models
Doctoral thesis
Permanent lenke
https://hdl.handle.net/11250/3107027Utgivelsesdato
2023Metadata
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Sammendrag
CO2 capture and storage is expected to play a vital role in reaching net zero emissions by 2050. In this context, large-scale CO2 pipeline transportation networks must be deployed. In order to perform safety analyses and ensure efficient operation of large-scale CO2 transportation systems it is key to predict the flow, in particular during depressurization events. This includes intentional depressurizations, e.g., the opening of a pressure relief valve, and accidental depressurizations, e.g., caused by a pipe fracture. High-capacity CO2 pipelines will be operated in the densephase region, meaning that the CO2 will boil during depressurization. This kind of boiling is denoted as flashing, and flashing often occurs delayed, i.e., at a lower pressure than the saturation pressure, out of equilibrium. The resulting pressure evolution and mass flow is highly dependent on the flashing process. Therefore, the focus of the present thesis is to gain more knowledge of this phenomenon through experiments and coupled thermo and fluid dynamics modeling.
In this work, a series of full-bore pipe depressurization experiments were conducted and analyzed, physics-based models for the mass-transfer during flashing have been investigated, and novel numerical methods have been developed for the simulation of non-equilibrium two-phase flows. The effect of homogeneous and heterogeneous bubble nucleation on the maximum attained superheat in the experiments has been investigated. It is found that homogeneous nucleation determines the superheat at warm conditions, i.e., near the critical point, and heterogeneous nucleation dominates otherwise. Homogeneous nucleation can be modeled by classical nucleation theory. This theory is applied herein to account for delayed boiling for flow through orifices and nozzles, and to improve the fluid curve in the Battelle two-curve method for the assessment of pipeline designs with respect to running ductile fracture. It is found that the combination of the crevice model and bubble growth for heterogeneous nucleation can explain the attained superheat at colder temperatures. A main result from this work is a homogeneous flashing model (HFM) for flashing flows. The mass-transfer model in the HFM accounts for bubble nucleation, coalescence, breakup and growth. The key finding from the analysis of this model is that both homogeneous and heterogeneous nucleation must be included in flashing flow models to capture the flow behavior during depressurization at warm conditions, including the relevant operating region of CO2 transportation pipelines. The present findings for flashing flows are general and relevant for other industrial applications including refrigeration systems and water cooling for pressurized water (nuclear) reactors.
Består av
Paper 1: Log, Alexandra Metallinou; Munkejord, Svend Tollak; Hammer, Morten. HLLC-type methods for compressible two-phase flow in ducts with discontinuous area changes. Computers & Fluids 2021 ;Volum 227. s. - This is an open access article under the CC BY license. Available at: http://dx.doi.org/10.1016/j.compfluid.2021.105023Conference paper: Log, Alexandra Metallinou; Munkejord, Svend Tollak; Hammer, Morten; Hafner, Armin; Deng, Han; Austegard, Anders. Investigation of non-equilibrium effects during the depressurization of carbon dioxide. I: 15th IIR-Gustav Lorentzen Conference on Natural Refrigerants - GL2022 - Proceedings - Trondheim, Norway, June 13-15th 2022. International Institute of Refrigeration 2022 ISBN 978-2-36215-045-6. Copyright © 2022 International Institute of Refrigeration. Available at: http://dx.doi.org/10.18462/iir.gl2022.0197
Paper 2: Hammer, Morten; Deng, Han; Austegard, Anders; Log, Alexandra Metallinou; Munkejord, Svend Tollak. Experiments and modelling of choked flow of CO2 in orifices and nozzles. International Journal of Multiphase Flow 2022 ;Volum 156. This is an open access article under the CC BY license. Available at: http://dx.doi.org/10.1016/j.ijmultiphaseflow.2022.104201
Paper 3: Skarsvåg, Hans Langva; Hammer, Morten; Munkejord, Svend Tollak; Log, Alexandra Metallinou; Dumoulin, Stephane; Gruben, Gaute. Towards an engineering tool for the prediction of running ductile fractures in CO2 pipelines. Process Safety and Environmental Protection (PSEP) 2023 ;Volum 171. s. 667-679. This is an open access article under the CC BY license. Available at: http://dx.doi.org/10.1016/j.psep.2023.01.054
Paper 4: Log, Alexandra Metallinou; Diky, Vladimir; Huber, Marcia. Assessment of a Parachor Model for the Surface Tension of Binary Mixtures. International journal of thermophysics 2023 ;Volum 44.(7). This is an open access article under the CC BY license. Available at: http://dx.doi.org/10.1007/s10765-023-03216-z
Paper 5: Log, Alexandra Metallinou; Hammer, Morten; Deng, Han; Austegard; Anders; Hafner, Armin; Munkejord, Svend Tollak. Depressurization of CO2 in a pipe: Effect of initial state on non-equilibrium two-phase flow. International Journal of Multiphase Flow 2024 ; Volum 170. This is an open access article under the CC BY license. Available at: https://doi.org/10.1016/j.ijmultiphaseflow.2023.104624
Paper 6: Log, Alexandra Metallinou; Hammer, Morten; Munkejord, Svend Tollak. A flashing flow model for the rapid depressurization of CO2 in a pipe accounting for bubble nucleation and growth. International Journal of Multiphase Flow 2023 ;Volum 171. This is an open access article under the CC BY license. Available at: http://dx.doi.org/10.1016/j.ijmultiphaseflow.2023.104666