LAUSR

Abstract The heat transfer characteristic of supercritical pressure water is a concerned issue in the thermal–hydraulic design of the supercritical water-cooled reactor (SCWR). In the present paper, a large eddy simulation (LES) was utilized to study the heat transfer of supercritical water in a circular pipe in forced convection (g = 0), upward and downward flow regimes. The pipe diameter was 2 mm and the length of the heated domain was 60 times diameter. To examine the effects of the drastic and non-linear thermophysical properties variation on heat transfer, the inlet temperature of water was set to 653.15 K which is close to the pseudo-critical temperature at 25 MPa. It was found that the heat transfer is slightly improved in the downward flow compared to the forced convection. On the other hand, the heat transfer is significantly impaired in the upward flow. The difference in the heat transfer features is attributed to the effects of buoyancy, which could be proved by analyzing the distribution of the turbulent statistics for the three flow regimes. In addition, the turbulent flow and thermal structure under upward and downward flows were provided. Six heat-transfer correlations were evaluated against the present LES data, which highlights the superior performance of the Chen and Fang (2014) correlation among the candidates.