A review on tube external heat transfer for passive residual heat removal heat exchanger in nuclear power plant

The nuclear power plant (NPP) has been developing for more than 60 years. Since Gen III NPP, the passive safety system has been firstly used to enhance operational safety, develop reliability and performance of the advanced nuclear power plant. There are several types of passive safety systems in existing Gen III NPPs, and the passive residual heat removal (PRHR) heat exchanger is a key facility in passive safety system. This paper mainly focuses on the tube external heat transfer mechanism and correlations study since the existing investigation is not sufficient, especially tube external subcooled boiling heat transfer research of PRHR heat exchanger in Gen III NPPs. The tube external heat transfer mechanism of PRHR heat exchanger is deeply analyzed here, and the empirical correlations proposed in literature are carefully summarized and classified in order to broaden the heat transfer calculation methods.