Thermal-hydraulic performance and particle deposition in a 19-rod wire-wrapped bundle with lead-bismuth eutectic alloy

The thermal–hydraulic performance and particle deposition in a 19-rod wire-wrapped bundle with lead–bismuth eutectic (LBE) are investigated to clarify the competing effects of flow conditions on heat transfer, hydraulic loss, and particle retention. A steady Reynolds-averaged Navier–Stokes model coupled with the discrete phase model is used to predict the LBE flow and heat transfer and the transport and deposition of Fe 3 O 4 particles. The model is validated against available data for heat transfer, friction factor, and particle deposition, showing good agreement with the reference results. The results show that Reynolds number is the main parameter governing the thermal–hydraulic response: higher Reynolds numbers strengthen transverse mixing and convective heat transfer, but increase the pressure drop. In contrast, particle deposition is controlled mainly by particle inertia. The deposition ratio remains low and changes only slightly in the low-Stokes-number regime, whereas it increases markedly as particle size and Stokes number increase. For the investigated conditions, the deposition ratio of fine particles is approximately 2–3%, while considerably higher deposition occurs for larger particles. Changes in flow velocity and bundle inclination produce comparatively smaller changes in deposition than those associated with particle size. These results indicate that improving thermal–hydraulic performance and suppressing particle deposition are not governed by the same controlling parameters, highlighting the need to evaluate the two aspects together rather than separately. On this basis, a dimensionless integrated performance index (IPI) is developed to account for the competing effects of heat-transfer enhancement, pressure loss, and particle deposition. The IPI identifies a favorable operating range that maintains the thermal–hydraulic benefit of wire wrapping while avoiding a disproportionate increase in particle deposition. The findings provide a quantitative framework for assessing the coupled thermal–hydraulic and particle deposition characteristics of LBE-cooled wire-wrapped rod bundles.