EXTRAPOLATION OF HEAT TRANSFER DATA FOR CARBON DIOXIDE TO THE OPERATING CONDITIONS OF SCWR

In this paper, a previously developed fluid-to-fluid similarity theory is applied to extrapolate experimental data obtained with carbon dioxide to corresponding conditions envisaged at the pressure of 25 MPa, considered as rated value for several conceptual designs of Super Critical Water cooled Reactors (SCWR). The similarity theory was applied in recent applications to different fluids showing a good qualitative and quantitative correspondence in phenomena actually observed to occur in real life conditions for carbon dioxide data collected in a recent literature work. The addressed CO2 experimental data are very systematic and allow for observing a full range of phenomena, including normal, enhanced and deteriorated heat transfer up to the transition to gas-like conditions in bulk and at the wall. For this reason, they were selected as an ideal workbench for testing the fluid-to-fluid similarity theory basing on RANS calculations with different fluids. In particular, previous analyses showed a very high level of similarity between the addressed experimental data and the predicted water conditions at a pressure of 24.5 MPa, selected on the basis of considerations related to fluid properties at the respective supercritical pressures. In this work, the not so different but largely more interesting value of pressure of 25 MPa is considered in order to show the scalability of the observed phenomena to operating conditions of greater interest for current SCWR conceptual designs.