Numerical study of flow and heat transfer of supercritical water in rifled tubes heated by one side

Deep understanding of flow and heat transfer of supercritical fluids in rifled tubes with non-uniform heating is of great importance for the safety of modern supercritical steam power equipment. In this paper, the heat transfer of supercritical water flowing in a vertical one-side heated rifled tube was numerically investigated. The differences of flow and heat transfer between the circumferentially non-uniform heated rifled tube (NRT) and uniform heated rifled tube (URT) were investigated. The distributions of temperature field, thermophysical properties, axial velocity and turbulent kinetic energy were analyzed. The mechanism of heat transfer improvement of NRT was comprehensively revealed. Results showed that the maximum inner wall temperature in NRT (Tiw,N,max) was 10 K lower than that in URT for the simulation conditions. Both radial and circumferential heat transfers were improved in NRT due to the swirling flow. Under high q/G (ratio of heat flux to mass flux) conditions, the buoyancy effect was weakened in NRT comparing to that in URT. Flow turbulence in boundary layer of y+ > 30 was intensified in NRT, which was crucial for supercritical fluid heat transfer. The positions of Tiw,N,max were not always at the midpoint of the heated side. And a prediction method for Tiw,N,max was proposed.