Enhancement of Oxygen Transfer in Liquid Lead-Bismuth Eutectic by Natural Convection

This article presents numerical analysis of natural convection and oxygen transfer of low-Prandtl-number (∼0.02) lead bismuth eutectic (LBE) for testing and calibrating oxygen sensors. This analysis is done on the two-dimensional coordinates in a rectangular container, when the fluid movement is laminar for the purpose of sensor test and calibration. The oxygen supply is from the bottom of the container. Natural convection and mass transfer are examined under several temperature boundary conditions: a) If heated from the lower part and cooled from the upper part of the sidewalls, there are four convective circulation cells. This will not benefit oxygen transfer from the bottom to the top of the container. b) If heated from the sidewalls and cooled from the top and the bottom of the container, there are two convective circulation cells side by side. This will lead to a weak oxygen transfer between left and right parts of the container. c) If one sidewall heated and the opposing wall cooled, there is a single convective circulation cell. This will produce intensive convective motion in the whole flow field. The simulation results show that the most efficient way to enhance oxygen transfer by natural convection is condition c). Under this condition, it takes about 12 minutes for the oxygen concentration in the whole field to reach ∼95% of the input oxygen concentration from the bottom, instead of ∼70,000 hours by pure diffusion.