A novel CFD-DPM model of adaptive gridded particle for particle deposition and heat transfer analysis in wire-wrapped rod bundles

Lead-bismuth eutectic (LBE), employed as a coolant in lead-bismuth fast reactors, exhibits strong corrosiveness and can erode metallic components within the reactor, thereby generating corrosion particles. As the coolant circulates, these particles may accumulate along the wire-wrapped fuel assembly, potentially causing blockages and overheating, which posing serious risks of nuclear accidents. Previous studies primarily investigated the effects of blockages on coolant flow and heat transfer by artificially inserting obstruction blocks. However, in practical scenarios, particle deposition rarely results in a single, well-defined blockage. This study focuses on the behavior of particle deposition and heat transfer processes in wire-wrapped rod bundles. First, the thermal-hydraulic characteristics of LBE are evaluated using computational fluid dynamics. The discrete phase model is applied to calculate the deposition of corrosion particles, while an energy balance model is employed to determine the criteria for particle deposition upon collision with wall. Subsequently, an adaptive gridded particle coupling time amplification algorithm is proposed to accelerate the simulation of long-term particle deposition by converting particles into computational grids. This method is used to explore the impact of particle deposition on the thermal-hydraulic behavior of wire-wrapped rod bundles. Finally, six cases with varying particle diameters and mass fraction are conducted to analyze their influence on flow blockage and heat transfer. The results indicate that increased particle deposition leads to elevated peak wall temperatures and greater inlet-outlet pressure differentials. With a particle diameter of 15 μm and mass fraction of 8.95 × 10⁻¹⁰ wt%, after 138,890 h, the peak temperature of the wall increases by 48.12 K compared to the baseline scenario without particle injection.