A numerical study of heat transfer to supercritical water flowing upward in vertical tubes under normal and deteriorated conditions

A numerical study of heat transfer to supercritical water in vertical tubes is carried out using the ANSYS-CFX code and employing the k–ω SST turbulence model. The numerical results on wall temperature distributions under normal and deteriorated heat transfer conditions are compared with experimental data and a good agreement is obtained. The onset of deterioration is captured for both low-flow and high-flow conditions. Sensitivity of numerical results to operational conditions and the turbulent Prandtl number (Prt) is investigated. The grid independent solution is obtained when y+ is less than 1 and the cell aspect ratio is less than 2000. It is concluded that the turbulent Prandtl number has a quite significant influence on the calculated wall temperature and the best agreement with experimental data is obtained when Prt is close to 0.9.