A comprehensive model has been developed for the computation of corrosion rates of carbon steels in the presence of lithium bromide-based brines that are used as working fluids for absorption refrigeration cycles. The model combines a thermodynamic model that provides realistic speciation of aqueous systems with an electrochemical model for partial cathodic and anodic processes on the metal surface. The electrochemical model includes the adsorption of halides, which
strongly influences the corrosion process. Also, the model takes into account the formation of passive fihns, which become important at high temperatures, at which the refrigeration equipment operates. The model has been verified by comparing calculated corrosion rates with laboratory data for carbon steels in LiBr solutions. Good agreement between the calculated and experimental corrosion rates has been obtained. In particular, the model is capable of reproducing the effects of changes
in alkalinity and molybdate concentration on the rates of general
corrosion. The model has been incorporated into a program that makes it possible to analyze the effects of various conditions such as temperature, pressure, solution composition or flow velocity on corrosion rates.
KEY WORDS: modeling, prediction, thermodynamics, electrochemical kinetics, lithium bromide, molybdate, refrigeration