Numerical Analysis of Critical Heat Flux Phenomenon in a Nuclear Power Plant Core Channel in the Presence of Mixing Vanes

Abstract

The necessity and importance of a high heat removal potential in various areas particularlyin nuclear applications are in a direct relationship with the excessively applied heat flux level. One wayto increase the heat transfer performance and subsequently enhance the threshold of the critical heatflux is to employ spacer grids accompanied by mixing vanes. In this study, the effect of the spacerswith mixing vanes on the critical heat flux characteristics in the dryout condition has been numericallyinvestigated employing the benefits of the Eulerian-Eulerian framework. In the current research, severalvane angles, including vane with 0, 15 and 25 degrees in comparison with the effect of the bare spacerwithout any mixing vanes on the flow characteristics were examined. It was shown that the existence ofthe spacer alone, delays the temperature jump under critical heat flux conditions. It was also concludedthat increasing the angle of the mixing vanes, further improves the heat transfer performance of thesystem by postponing the sudden temperature jump occurring in the channel; however, the presence ofthe spacers and vanes in the flow field imposes an increase of the pressure drop due to the constrictionon the coolant flow area.