Numerical simulation and comparison of turbulent heat transfer in supercritical and subcritical water

In this study, the heat transfer of supercritical water in uniformly heated vertical tube is numerically investigated with three different turbulence models, i.e., the renormalisation group (RNG) k-ε model, the shear stress transport (SST) k-ω model and the Reynolds stress model (RSM). In order to find suitable turbulence models for engineering applications, for example, the supercritical water-cooled reactor (SCWR), the results are compared with experimental results by Yamagata et al. (1972) firstly. It has been found that, as the physical properties of supercritical water change rapidly with temperature in pseudo-critical region, these turbulence models, which are simplified, based on isotropic flow and constant physical properties, do not agree well with the experimental results, and even fail in some cases. The numerical results of RSM are also not good enough as expected near critical point. To further explore the flow and heat transfer mechanism in supercritical water, sub-cooled nucleate boiling under subcritical pressure is also numerically investigated in order to find the similarities and differences with those under supercritical pressure.