VELOCITY AND ENTHALPY FIELDS AND EDDY DIFFUSIVITIES IN A HEATED SUPERCRITICAL FLUID-FLOW

Together with a brief description of the technology of the experimental study of hydraulic resistance, the fields of velocity and temperature in a supercritical CO2 flow (P = 9.0 MPa) through a heated vertical circular tube (22.7 mm. in diameter), experimental data are presented on the structure of averaged flow for the conditions of normal and deteriorated heat transfer at large Reynolds numbers (Re(in) = 2.3 x 10(5)-1.18 x 10(6)). Making use of the experimental results and the integral equations of continuity, energy, and motion, taken in the narrow-channel approximation, the profiles of shear stresses, heat fluxes, gradient coefficients of eddy diffusivities of heat and momentum, and turbulent Prandtl numbers are determined. A comparative analysis is made for the flow structure in the conditions of normal and deteriorated heat transfer, as well as for the upward and downward flow directions. The experimental data are compared to some models of turbulent heat transfer in flows with constant and variable physical properties.