Nonuniform heat transfer of supercritical pressure carbon dioxide under turbulent cooling condition in circular tubes at various inclination angles

Abstract

In current work, we conducted a numerical simulation about the turbulent mixed convection and heat exchange of supercritical pressure carbon dioxide (SCO2) cooled by constant heat flux in inclined circular channel with equal cross-section. Result shows that the inclination angle of the channel has considerable effect on the arrangement of temperature, velocity, turbulent kinetic energy (TKE) as well as wall shear stress. The nonuniformity of local heat transfer coefficient (LHTC) is remarkably influenced by inclination angle, heat flux density, and gravity force level. Parameter Gr/Re2 is chosen to describe the buoyancy effect induced by density difference, and the buoyancy effect results in heat transfer enhancement. The maximal heat transfer coefficient (HTC) is seriously decreased with the deviation of the operating pressure from the critical pressure.