Design of a 10 MW/m2-heat-flux removal system for a W7-X divertor tile using triply periodic minimal surfaces

In nuclear fusion reactors, the heat removal from high-heat-flux components such as the divertor has always been a challenge as the heat flux is anticipated to easily overcome 10 MW/m(2), as it is the case for the divertor tiles in the W7-X stellarator. In this paper a new cooling solution, relying on a Triply Periodic Minimal Surface lattice, is proposed and investigated. The analysis first focuses on the identification of the optimal lattice with a dedicated investigation on a reduced computational domain. The analysis with the best candidate is moved to a 30cm x10 cm divertor tile, to prove the compliance with the operating constraints. The tile with the gyroid lattice with unit cell size of 10 x 10 x 5 mm(3) is shown to be capable to withstand a heat flux of 10 MW/m(2), distributed over a heated length of 10 cm, when 1.25 kg/s of subcooled water are used for cooling, resulting in a pressure drop <0.6 MPa and tolerating a very limited fluid boiling just around the inlet/outlet manifolds. Eventually, the benefits of this configuration, when compared to others, in terms of enhancement of the performance and structure lightning, are discussed.