Numerical simulation of three-dimensional flow and heat transfer characteristics of liquid lead–bismuth

Abstract

Liquid lead-bismuth cooled fast reactor is one of the most promising reactor types among the fourth-generation nuclear energy systems. The flow and heat transfer characteristics of lead-bismuth eutectic (LBE) are completely different from ordinary fluids due to its special thermal properties, causing that the traditional Reynolds analogy is no longer recommended and appropriate. More accurate turbulence flow and heat transfer model for the liquid metal lead-bismuth should be developed and applied in CFD simulation.In this paper, a specific CFD solver for simulating the flow and heat transfer of liquid lead-bismuth based on the k - ε - kθ- εθ model was developed based on the open source platform OpenFOAM. Then the advantage of proposed model was demonstrated and validated against a set of experimental data. Finally, the simulation of LBE turbulent flow and heat transfer in a 7-pin wire-wrapped rod bundle with the k - ε - kθ- εθ model was carried out. The influence of wire on the flow and heat transfer characteristics and the three-dimensional distribution of key thermal hydraulic parameters such as temperature, cross-flow velocity and Nusselt number were studied and presented.Compared with the traditional SED model with a constant Prt = 1.5 or 2.0, the k - ε - kθ- εθ model is more accurate on predicting the turbulence flow and heat transfer of liquid lead-bismuth. The average relative error of the k - ε - kθ - εθ model is reduced by 11.1% at most under the simulation conditions in this paper. This work is meaningful for the thermal hydraulic analysis and structure design of fuel assembly in the liquid lead-bismuth cooled fast reactor.