Migration–deposition coupling characteristics and influence of corrosion products on heat transfer in steam generators

Abstract

• A coupled model of impurity migration-deposition considering boiling is developed. • A critical time step is proposed to realize the simulation time to the real scale. • The whole lifetime fouling characteristics are predicted in steam generators. • The effects of fouling on heat transfer of steam generator is investigated. Fouling on tube surfaces degrades the heat transfer characteristics of heat exchangers. The objective of this study was to predict the distribution of deposits on the surface of heat transfer tubes and assess its influence on heat transfer characteristics. For this purpose, a comprehensive model of impurity migration and deposition, which considered deposition and removal processes under boiling conditions, was established to simulate the fouling characteristics of steam generators. A critical time step was determined to solve the problems at a large time-scale span between the fluid flow and long-term deposition time in actual operation. Then, the deposit distribution was used to propose a fouling thermal resistance model based on the Maxwell model to study the influence of fouling on the heat transfer performance of steam generators. The results showed that the corrosion products were mainly deposited on the hot side and in the U-bend region. The deposition rate on the hot side gradually decreased with time, whereas the deposition mass on the cold side linearly increased with time. Fouling had an evident effect on the overall heat transfer efficiency and distribution of steam generators. This study is relevant for the prediction of operating conditions during the life cycle of heat exchangers in industry.