Study on the fouling effect on OTSG flow and heat transfer performance

During power operation of nuclear reactors, corrosion products of various materials may deposit and form fouling on the primary and secondary sides of Once Through Steam Generator (OTSG) heat transfer tubes. Fouling will change the local flow area and heat transfer coefficient of heat transfer tubes, thus affecting the flow and heat transfer performance of OTSG. In this paper, a theoretical model of fouling effect on flow and heat transfer performance of nuclear OTSG is proposed, and the fouling experiment of OTSG heat transfer tubes is conducted. Based on LOCUST software, the flow and heat transfer capability of an OTSG at different fouling levels is compared. The results show that the fouling distribution on the primary side of OTSG heat transfer tube is uniform, which will lead to the increase of wall temperature and the decrease of wall pressure. The fouling on the secondary side of OTSG tubes is mainly concentrated in the two-phase region because of the influence of coolant flow pattern. The fouling will lead to the increase of wall temperature and the decrease of vapor super-heat, void fraction and pressure at the outlet of OTSG tubes. Microscopically, fouling will reduce the overall flow and heat transfer efficiency of OTSG.