A predictive model is described to simulate the aqueous CO2 corrosion of iron in turbulent pipe flow. Mass transfer is modelled with a two dimensional low Reynolds number k- 3 turbulence model by simultaneously solving the conservation equations for mass, momentum, kinetic energy of turbulence and its dissipation rate, along with the concentrations of various dissolved species. The effect of the slow homogeneous chemical reaction Of CO2 hydration is incorporated into the model by including an extra source term in the transport equation for carbonic acid. Other homogeneous chemical reactions are assumed to be in equilibrium. The electrochemical reactions considered are iron dissolution and the reduction of H2CO3, H+ and H 2O. An iterative procedure is employed to calculate CO2 corrosion rates by ensuring the mixed potential theory is satisfied and the various surface chemical equilibria are preserved. It is shown that at a bulk PH 4 and very low flow velocities the reduction of H2CO3 is controlled by CO2 hydration. At higher velocities and in the high current density region where Tafel behavior is no longer observed, H2CO3 reduction is controlled by the interaction of chemical reaction (CO2 hydration) and mass transfer. The H+ reduction is more flow sensitive than the H2CO3 reduction. CO2 corrosion is more influenced by flow at PH 4 than at higher PH values. Generation of H 2CO3 by CO2 hydration enhances the H2CO 3 mass transport and reduces the H2CO3 mass transfer entrance length. The relative contributions of H2CO3, H+, find H2O reduction to the corrosion current depend on the solution PH. The CO2 corrosion rate is accelerated by turbulent flow and CO2 partial pressure through an approximate power law. Present model predictions were tested against experimental findings and other models. Good agreement is achieved. A simplified spreadsheet-based electrochemical model of CO2 corrosion is also developed. Overall mass transfer coefficients.

This thesis describes the application of the low Reynolds number (LRN) k-$\varepsilon$ eddy viscosity model and an electrochemical (or corrosion) model to simulate the corrosion rate, the metal/solution interface concentration of both oxidants and corrosion products, and the film formation conditions in turbulent pipe flow. The overall objectives of this study were the numerical simulation and experimental investigation of the effects of flow on the corrosion rate and film formation and disruption under both attached and disturbed flow conditions. The turbulence model used in this study is based on the standard k-$\varepsilon$ model proposed by Launder and Spalding (1974). The model was modified with a recently developed LRN model (Abe et al, 1994) in the near wall region which enables the calculation of species concentration all the way down to the wall. The mass transfer was modelled by simultaneously solving the transport equation for mass, momentum, kinetic energy of turbulence and its dissipation as well as species concentration. The corrosion model was developed to construct E/logi diagrams which take into account the effects of mass transfer resistance on the anodic and cathodic reactions. The pipe-wall mass transfer in the mass transfer entrance region has been simulated with LRN k-$\varepsilon$ model and tested against the experimental results of Berger and Hau (1977), in the range Re = $10\sp4$ to $10\sp5,$ for Sc = 2244, and of Son and Hanratty (1967), in the range Re = $10\sp4$ to $5 10\sp4,$ for Sc = 2400, in both the mass transfer entrance region and the fully developed region and good agreement was reported. The application of small cathodes embedded in a larger active cathode to measure local mass transfer rates was also simulated. The size of the electrode and the thickness of the electrical insulation around the small electrode give rise to errors that increase as the insulation thickness increases and the electrode size decreases. Effects of mass.

A collection of articles by leading international experts on modeling and control of potable water distribution and sewerage collection systems, focusing on advances in sensors, instrumentation and communications technologies; assessment of sensor reliability, accuracy and fitness; data management including SCADA and GIS; system

This four-volume reference work builds upon the success of past editions of Elsevier’s Corrosion title (by Shreir, Jarman, and Burstein), covering the range of innovations and applications that have emerged in the years since its publication. Developed in partnership with experts from the Corrosion and Protection Centre at the University of Manchester, Shreir’s Corrosion meets the research and productivity needs of engineers, consultants, and researchers alike. Incorporates coverage of all aspects of the corrosion phenomenon, from the science behind corrosion of metallic and non-metallic materials in liquids and gases to the management of corrosion in specific industries and applications Features cutting-edge topics such as medical applications, metal matrix composites, and corrosion modeling Covers the benefits and limitations of techniques from scanning probes to electrochemical noise and impedance spectroscopy