CFD Analysis on the Multiphase Flow of the Wickless Sodium Heat Pipe with Non-condensable Gas

The heat pipe cooling reactor (HPR) is a new advanced reactor with small size, lightweight, and inherent safety. The high-temperature alkali metal heat pipes are essential components of the heat pipe cooling reactor. A multiphase flow CFD model for sodium heat pipe considering non-condensable gas was proposed, which integrates the network model. Numerical simulation of the evaporation, condensation, and heat transfer process inside the heat pipe was completed with the two-dimensional model during the steady-state operation. A length of 800 mm sodium wickless heat pipe was selected for the heating experiment. The correctness of the CFD model was verified by comparison with the experimental results. Temperature fluctuations were observed in the sodium heat pipe with 702.4 W heating power. Meanwhile, the heat pipe axial temperature difference was evident due to the presence of non-condensable gas. The results show that non-condensable gas reduces the effective working length of the heat pipe and degrades the performance of the sodium heat pipe.