Heat transfer characteristics of supercritical water in different shape channels

Background: Supercritical water reactor (SCWR) is the only one that uses light water as a coolant among all fourth generation nuclear reactors. Purpose: This study aims to investigate the characteristics of supercritical water heat transfer in various pipelines. Methods: The models of rectangular, triangular, circle and annular channels are employed, with equivalent diameters of 2 mm, 3 mm and 5 mm for each of them. Based on these models, heat transfer charactersistics of supercritical water in different shape channels at certain mass flow and fluid velocity were calculated via ANSYS CFX. Results: There are two situations for the same equivalent diameter: in the condition of constant mass flow rate, the heat transfer property of circle channel outperforms other three types of channels, and the smaller equivalent diameter channels, the better of the heat transfer. In constant fluid velocity condition, the heat transfer property of annular channel presents best performance over others, and the smaller equivalent diameter channels, the better of the heat transfer in subcritical condition whilst the bigger equivalent diameter channels, the better of the heat transfer in supercritical condition. Conclusion: Compared with the experimental results, the model can provide a certain reference for the design of supercritical water reactor. (authors)