CFD analysis using two-equation turbulence models for the vertical upward flow of water in a heated tube at supercritical pressure(I)

Numerical simulation was performed referring to the Yamagata's experiment on the heat transfer in a vertical tube where water flows upward at supercritical pressure. Numerical simulation was performed for the conditions of tube diameter of 7.5 mm, heated tube length of 2 m, operation pressure at 245 bar, bulk temperatures from 300 to 420 .deg. C, heat fluxes from 465 to 930 kW/m2 and mass velocity 1,260 kg/m2s, by Fluent code and compared with the Yamagata's experiments. At the heat flux 465 kW/m2, the maximum difference between calculated results and Yamagata's experiment were less than 20% and the difference between the results using different turbulence models was not so significant. But at the heat flux, 930 kW/m2, the difference between the calculations and Yamagata's experiment increased to about 25%, and the difference between the results using different turbulence models increased significantly. The case with RNG κ-ε and enhanced wall treatment predicted the Yamagata's experiment best