A study on carbon steel corrosion for the development of LiBr-H2O triple-effect absorption chillers.

Triple-effect absorption chillers are expected to have more severe corrosion problems since the solution temperature in the high-temperature generator is higher than double-effect systems. Therefore, a comprehensive study on the corrosion characteristics of the materials constituting the system is essential to develop a triple-effect absorption chiller successfully. In this study, the corrosion characteristics of the carbon steel (SS400) were investigated in various operation conditions. Pyrex tube ampoules containing the specimen (3 mm x 5 mm x 60 mm) and various solutions were manufactured and placed in a high-temperature oven with a temperature of 150°C and 200°C. The solutions have different LiBr concentrations (60% and 63%), and the concentrations of the corrosion inhibitor Li2MoO4 (0 ppm, 300 ppm, and 600 ppm). After 2,200 hours, the ampoules were opened, and the change of the mass of specimens and the solution components were analyzed. It was found that the mass reduction and Fe concentration in the solution increased greatly if the solution did not contain the corrosion inhibitor. However, the effect of the amount of the inhibitor (300 or 600 ppm) was not clear. The corrosion rate increased with the temperature and solution concentration, as expected. Especially, the corrosion rate was found to increase several times if the concentration is changed from 60% to 63%.