Study on the flow and heat transfer characteristics of Li4SiO4 pebble bed based on DEM-CFD coupling

Abstract

The blanket is a key component for producing tritium in fusion reactors. To ensure the blanket operates effectively and safely, it is crucial to maintain efficient heat transfer in the pebble bed. Furthermore, the breeder material needs to operate within a specific temperature range to achieve optimal performance. To investigate how temperature influences thermal transport within the pebble bed and enhance the thermal performance of the solid breeder system, this study took the tritium breeder lithium orthosilicate pebble bed as the research object, established a single-size randomly stacked lithium orthosilicate pebble bed model, and studied the temperature-dependent characteristics of internal flow and heat transfer through numerical simulation calculations. The simulation results indicate that gas flow velocity within the pebble bed is affected by the stacking structure of the pebbles. The gas flow velocity increases significantly at locations with larger local pores, and the higher the pebble bed temperature, the greater the increase. Additionally, higher temperatures lead to increased overall bed pressure drop. The effective thermal conductivity of the pebble bed is found to increase as temperature rises, and a correlation formula is fitted to represent its temperature dependence based on the simulation data.