Numerical investigation of heat transfer deterioration and the variation of Prandtl number in the main flow area under supercritical conditions

Abstract

The problem of heat transfer deterioration (HTD) exists in supercritical conditions of the power plant during peak operation. The turbulence model is selected to be applicable to the cross-critical flow field, and the different simulation models results are compared with the Yamagata experimental data. The different inner diameters and heat fluxes have a significant effect on the HTD, accompanied by variation in the Prandtl number change rate. This change can be expressed by the full width at half maximum of the Pr number along the bulk fluid enthalpy. It is analyzed that the HTD is related to the layer difference between the temperature boundary layer and velocity boundary layer, and to the decrease of the thermal conductivity inside the temperature boundary layer near the wall.