Heat Transfer Enhancement Technique with Copper Fiber Porous Media

In a fusion reactor, almost 30% of fusion energy is deposited on plasma facing components. In the divertor region, it is, however, difficult to utilize this energy with conventional cooling techniques based on high velocity flow with highly subcooled cooling. From this viewpoint, the authors have been developing a cooling technique with metal porous media. In this study, in order to attain both the higher cooling performance and the acquisition of high density energy, high heat removal experiments are performed by using homogeneous and functionally graded porous media to estimate their fundamental heat transfer performances. From the experiments with the homogeneous porous media, it is clarified that the cooling performance is not always improved by using finer pore size media. The functionally graded porous media can reduce a pressure loss. Additionally, in case of the functionally graded porous media with the finer pore, the heat transfer coefficient is higher than that obtained in the homogeneous case. As for the optimal design, it is important to consider the degree of vapor development near a heated surface in the porous media and an effective discharge of vapor from the heated region.