Heat transfer performance of an energy-saving heat removal device with uni-directional porous copper for divertor cooling

Abstract

Heat transfer performance of divertor cooling device EVAPORON-4, which was developed in order to remove a high heat flux of 10 MW/m2 under low pumping power conditions, is evaluated. Uni-directional porous media used in EVAPORON-4 make it possible to promote evaporative heat transfer in microchannels of the porous medium due to its high effective thermal conductivity. In this study, we evaluate effect of soldering the uni-directional porous medium onto a grooved heat transfer surface on boiling and evaporative heat transfer performance. The heat transfer experiments prove that the boiling heat transfer performance is highly enhanced by soldering the porous medium onto the grooved surface due to the promotion of evaporation in the uni-directional porous medium and that the critical heat flux is also further increased. In particular, a high heat flux of 9.1 MW/m2, which is not critical heat flux, is achieved at 1.0 L/min and the liquid subcooling of 70 K. The pumping power characteristics also verify the evaporation promotion in the uni-directional porous medium and clarify the issues of EVAPORON-4 including the porous structure.