Development of a heat sink module for a near-term DEMO divertor

A heat sink module has been developed for high-heat flux applications in the divertor region of a near term DEMO divertor. The concept employs water jet impingement, in a cascading flow path, together with CuCrZr as the structural material. This fluid-flow architecture maximises the heat transfer coefficient obtained for a given coolant flow rate. Combined with high operational pressures, it facilitates increased coolant outlet temperatures. A conjugate CFD study was performed to compare its performance to the ITER divertor under a representative heat flux boundary condition of 10 MW/m2. A transient thermochromic liquid crystal technique was used to experimentally validate the CFD heat transfer data, using air as the working fluid at matched Reynolds numbers. These results showed that area averaged heat transfer coefficients could be accurately predicted by the CFD to within ∼12%.