A Numerical Study to Investigate the Effect of Inlet Reynolds Number on the Thermal–Fluid Phenomena in the Supercritical Carbon Dioxide-Cooled Pebble Bed Reactor

Abstract

This paper presents a numerical investigation into thermal–fluid phenomena in a supercritical carbon dioxide-cooled pebble bed reactor (SCPBR) core under steady state using computational fluid dynamic. In this study, a three-dimensional model with the capability to simulate the fluid flow and heat transfer in the SCPBR core has been developed. The developed model was implemented on a personal computer using ANSYS Fluent 14.5. Several important fluid flow and heat transfer parameters have been examined, including the pressure drop over the reactor core, the heat transfer coefficient, the temperature distribution, the coolant density and the coolant velocity. Results obtained from the simulation show that with increasing the inlet Reynolds number, the pressure drop, the coolant density and the heat transfer coefficient increase. However, the coolant temperature and the temperature difference between pebble and coolant decrease with increasing the inlet Reynolds number. The conclusion of the analysis is that supercritical carbon dioxide (S-CO\(_{2})\), compared to other coolants such as helium, could be a suitable coolant for use in a pebble bed reactor due to its large mass density and heat transfer characteristics, which could lead to obtain a higher temperature rise and a lower pressure gradient.