MIXED-CONVECTION HEAT-TRANSFER TO SODIUM IN A VERTICAL PIPE

Experimental turbulent mired-convection data are presented for sodium in a uniformly heated vertical pipe. The behavior is found to be opposite to that established for fluids of higher Prandtl number, including mercury, with heat transfer enhanced in upward flow and impaired in downward flow. Velocity and temperature profiles in the sodium have been measured using miniature magnet probes. Velocity profiles are similar to those observed under comparable conditions in other fluids; temperature profiles are somewhat different, with significant variation of temperature extending almost to the pipe centerline. Experimental measurements are compared with predictions obtained using a low-Reynolds-number k-epsilon turbulence model. Reasonable agreement is achieved for upward flow but the model overpredicts heat transfer rates for downward flow, as in the case of conventional fluids.