Comparison between tritium breeders with pebble bed and Gyroid block configurations using numerical investigation: Flow behavior and heat transfer performance

This study proposed using a Gyroid structure, a type of triply periodic minimal surface (TPMS), to replace conventional pebble bed configurations and address drawbacks such as inherently low packing fractions, extensive stress concentrations, high flow resistance, and low thermal conductivity. The feasibility of the Gyroid block configuration was evaluated by comparing it with a pebble bed configuration regarding the flow behaviors and heat transfer performance. The flow behavior of the porous block configuration was superior to that of the pebble bed configuration. At the same inlet velocity of 0.1–0.2 m/s, the porous block configuration had a ∼56 % higher average flow velocity and only half the pressure drop. The convective heat transfer coefficient and Nusselt numbers in the porous block configuration were 56–84 % and 2.6–3.1 times higher, respectively, than those in the pebble bed configuration. The effective thermal conductivity of the porous block configuration increased by ∼18 % at an inlet velocity of 0.15 m/s and a temperature of 773–1173 K. This study preliminarily verified the feasibility of the Gyroid structures for tritium breeders in engineering applications and is anticipated to provide new opportunities for the design of tritium breeders with higher lithium densities, remarkable flow behavior, and outstanding thermal performance.