EXPERIMENTAL STUDY ON HEAT TRANSFERTO SUPERCRITICAL CARBON DIOXIDEFLOWING UPWARD IN A VERTICAL TUBE

摘要

This paper presents selected results on heatrntransfer in supercritical CO2 flowing upward in arnvertical tube at supercritical water-cooled (SCW)rnCANDU? reactor equivalent operating conditions.rnSupercritical CO2 heat-transfer data were obtained atrnthree pressures above the critical point (7.6, 8.4 andrn8.8 MPa), mass fluxes from 900 to 3000 kg/m2s, heatrnfluxes up to 600 kW/m2 and inlet temperatures fromrn20 to 40℃.rnResults are given for supercritical heat transferrnfor several combinations of wall and bulk fluidrntemperatures that were below, at or above thernpseudocritical1 temperature. Uncertainties of allrnprimary parameters were estimated.rnTwo modes of heat transfer at supercriticalrnpressures have been identified: (1) so-called normalrnheat transfer, and (2) deteriorated heat transfer,rncharacterized by lower-than-expected heat transferrncoefficients (HTCs) (i.e., higher-than-expected wallrntemperatures) than in the normal heat-transferrnregime.rnThese heat transfer data are applicable for thernverification of scaling parameters between water andrnCO2.