Modeling and simulation of a supercritical CO2-liquid sodium compact heat exchanger for sodium-cooled fast reactors

摘要

The study focuses on modeling and simulations of sodium-sCO2 intermediary compact heat exchangers for sodium-cooled fast reactors (SFR). A simplified 1-D analytical model was developed in companion with a 3-D CFD model. Using classic heat transfer correlations for Nusselt number, some simulation results using the 1-D model have achieved reasonable match with the CFD simulation results for longer channels (i.e., 40 cm and 80 cm). However, for short channel (10 cm) when axial conduction within the sodium fluid is significant, the 1-D model significantly over-predicted the heat transfer effectiveness. By incorporating the temperature-jump model, the 1-D model can extend its predictive capability for low-Prandtl number fluid/Peclet number flows. The results can help improve the understanding of heat transfer for sodium and low-Prandtl number fluids in general and improve designs of sodium-sCO2 compact heat exchangers. The results also confirmed that the sCO2 side dominates the overall heat transfer for Na-sCO2 heat exchangers. A preliminary attempt of optimizing the channel geometry shows mixing results - while heat transfer effectiveness was significantly increased for the wavy channel, much greater pressure drop was also predicted by the simulations.