Wall Shear Stress and Mass transfer rates - important parameters in CO2 corrosion.
M. Langsholt, M Nordsveen and K Lunde.

The modeling and understanding of fluid flow and CO2-corrosion is of decisive importance for economic and safe use of multiphase transport technology. Shear stresses and shear stress fluctuations at the wall can have a significant effect on the survival of the corrosion product films and the inhibitor persistency. In addition, the shear stress is important for the liquid holdup and the pressure drop through the pipeline. Mass transfer rates of species towards and from the pipe wall is one of the parameters, which influence the CO2-corrosion rates.
This paper presents the results from a study of stratified two-phase flow in a horizontal pipe, focusing on the measurement of wall shear stresses and mass transfer rates. In addition, standard parameters such as superficial velocities, pressure drop and liquid holdup in the test section were measured. Two different techniques were used to measure the wall shear stresses. These are the hot-film technique and an electrochemical method – which compared well. The latter method was also used for the measurement of the mass transfer rates.
The mean hydrodynamic flow data prove to agree well with predictions obtained with the steady two-phase flow model WOLGAAS695. However, the modeling of mean mass transfer rates based on this flow model and the Berger & Hau (1977) correlation is shown not to compare favorably with the presented experimental data.


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