Numerical heat transfer to LBE flow in a wire-wrapped 19-rod bundle using an OpenFOAM-based solver: fourParameterFoam

Abstract

The LBE-cooled fast reactor (LFR) has received significant attention due to its diverse applications. However, numerical heat transfer simulations encounter challenges with lead-bismuth eutectic (LBE) due to its low Prandtl number and high molecular thermal diffusion, often resulting in an overestimation of heat transfer using the simple gradient diffusion hypothesis (SGDH). This study aims to improve the prediction accuracy of heat transfer to LBE in numerical models by developing a solver, named fourParameterFoam, based on the turbulent model SST k-ω and algebraic heat flux model (AHFM) kθ-ɛθ within the OpenFOAM framework. The performance of SGDH models and AHFMs is compared based on heat transfer experiments in vertical tube flow with LBE. The behavior of the turbulent Prandtl number (Prt) under various flow conditions is concluded based on the SST k-ω-kθ-ɛθ model. Additionally, the applicability of the SST k-ω-kθ-ɛθ model in complex flow is validated through heat transfer experiments in a wire-wrapped 19-rod bundle with LBE flow. Local temperature variations on the heated rod surface and sub-channels are analyzed to elucidate the thermal development process in the bundle. The impact of wire spacers on flow behavior is summarized using visualization techniques, and the suitability of corresponding empirical Nusselt number correlations in LBE flow is evaluated.