Investigation of effective thermal conductivity for pebble beds by one-way coupled CFD-DEM method for CFETR WCCB

• A CFD-DEM coupled numerical model is built based on the prototypical blanket pebble bed.
• The numerical model can be applied to simulate heat transfer of a pebble bed and estimate effective thermal conductivity.
• The numerical model agrees well with the theoretical SZB model.
• Effective thermal conductivity of pebble beds for WCCB is estimated by the current model.

The mono-sized beryllium pebble bed and the multi-sized Li2TiO3/Be12Ti mixed pebble bed are the main schemes for the Water-cooled ceramic breeder blanket (WCCB) of China Fusion Engineering Test Reactor (CFETR). And the effective thermal conductivity (keff) of the pebble beds is important to characterize the thermal performance of WCCB. In this study, a one-way coupled CFD-DEM method was employed to simulate heat transfer and estimate keff. The geometric topology of a prototypical blanket pebble bed was produced by the discrete element method (DEM). Based on the geometric topology, the temperature distribution and the keff were obtained by the computational fluid dynamics (CFD) analysis. The current numerical model presented a good performance to calculate keff of the beryllium pebble bed, and according to the modeling of the Li2TiO3/Be12Ti mixed pebble bed, keff was estimated with values ranged between 2.0 and 4.0 W/(m∙K).