Heat Transfer Characteristics of a Pipeline for CO2 Transport with Water as Surrounding Substance

The heat transfer characteristics of pipelines for transport of CO2 is crucial for the events following a depressurization or a crack formation, involving rapid cooling. In this work, we present and analyze recent experiments from an experimental facility tailored to investigate these phenomena. With stagnant water as the surrounding substance, we quantify the contribution to the heat transfer from the surroundings, the insulation and the CO2 boiling inside the pipeline, for a large set of operating conditions. We discuss whether empirical expressions in the literature can describe the outer heat transfer coefficient and analyze the experimental results in detail using computational fluid dynamical simulations. The work gives insight into and quantifies the heat transfer characteristics of a CO2-pipeline. In particular, the outer heat transfer coefficient was between 80 and 210 W/m2 K, the thermal conductivity of the insulation was well described by a linear temperature relation and the mean value of the overall heat transfer coefficient was 44.7 W/m2 K. The work lays the foundation for future work on this subject, which will involve other surrounding substances such as clay and gravel as well as the forming of ice.