Experimental Study of Water Flow at Supercritical Pressures

Abstract

Future supercritical water cooled nuclear reactors will operate at coolant conditions around of 25 MPa and 500-625°C. Using coolant pressures higher than critical values avoid critical heat flux to occur while outlet flow enthalpies will be much higher than actual reactors. Increasing this property permits plant efficiencies of up to 48% to be achieved. Under such flow conditions, thermalhydraulics behaviors of supercritical water are not fully known (pressure drop, heat transfer deterioration, critical flow rate.) Up to now, only a very limited number of studies in these areas have been performed; thus, knowledge of critical discharge of supercritical fluids is mandatory to perform nuclear reactor safety analyses. Nevertheless, existing choked flow data have been collected from experiments at atmospheric discharge pressure. For this reason, an experimental supercritical water facility has been built at École Polytechnique de Montréal. In this paper, preliminary results obtained using this facility are presented and discussed.