Investigation of heat transfer coefficients in high pressure two-phase flow in a straight-type heat transfer tube for a FBR steam generator

For a steam generator with straight double-walled heat transfer tubes that will be used in sodium cooled faster breeder reactor, clarification of flow instability in heat transfer tubes is one of the most important research themes. As the first step of the research, thermal hydraulics experiments with water were performed under high pressure condition in JAEA with using a circular tube. Pressure drop, heat transfer coefficients and void fraction data were derived. This paper summarizes the heat transfer characteristics under 15-18 MPa. Saturated boiling heat transfer was discussed with four most famous general heat transfer correlations (Chen, Shah, Steiner-Taborek and Gungor-Winterton) being verified. Under present high pressure condition, it was found that the Shah correlation gave good agreement with data at low mass flow rate and the Chen correlation gave good agreement at high mass flow rate condition. For the nominate flow rate of w=110 g/s, both Chen and Shah correlations can be used. As a result, under present high pressure condition, we recommend that the smaller one of the Chen and Shah correlations be used for the calculation of heat transfer coefficient. (author)