Corrosion effect analysis on thermal-hydraulics of LBE/water spiral tube steam generator under oxygen-controlled environment

Abstract

The advancement of utilizing liquid Lead-Bismuth Eutectic (LBE) as a cooling medium is hindered by its pronounced corrosive properties. The impact of LBE corrosion on the performance of heat exchangers is significant over the long term, however, this aspect has been largely overlooked in previous studies. Historically, there has been a dearth of LBE corrosion models that account for flow accelerated corrosion. Concurrently, precise numerical models and coupling methods for comprehending the interplay between LBE corrosion and thermal-hydraulics have not been developed. Nevertheless, these contents are pivotal for the advancement of liquid LBE cooling mediums. To delve into the flow and heat transfer characteristics of heat exchangers subjected to LBE corrosion, enhancements were made to capture the accelerated removal effect of LBE corrosion flow. Subsequently, a bidirectional coupling model encompassing LBE corrosion and flow heat transfer was formulated. The Computational Fluid Dynamics (CFD) method was employed to simulate the corrosion and flow heat transfer in a spiral tube steam generator under conditions of saturated oxygen concentration and an oxygen-controlled environment. The results indicate that the corrosion of liquid LBE forms an oxidation layer, which hinders the heat transfer in the spiral tube steam generator. This leads to a significant increase in the wall friction coefficient and a decrease in the surface Nusselt number. However, it does not have a significant effect on the water side evaporation process of the spiral tube steam generator. The implementation of an oxygen-controlled environment can effectively reduce the influence of LBE corrosion on the flow heat transfer of the spiral tube steam generator. Especially under high temperature conditions, it can reduce the near wall temperature of LBE change by up to 57.5% and the outlet temperature change by up to 61.5%. The oxygen-controlled environment results in prolonged local hypoxia time, with a more pronounced effect at higher temperatures.