Speaker
Youngjae Park
(Department of Nuclear Engineering)
Description
Development of reliable high heat flux removal techniques is an important issue to design plasma facing components in a fusion reactor. The ITER-like divertor cooling design based on water-subcooled flow boiling is one of the well-developed divertor cooling schemes. To withstand such a high heat flux in the vertical target of the ITER divertor, a twisted tape is inserted into a CuCrZr tube imbedded in a tungsten monoblock, which is called the swirl tube. The twisted tape generates the rotational swirl flow along with axial flow, which can effectively tear off vapor bubbles from the tube wall in water-subcooled flow boiling and thus enhance critical heat flux (CHF). However, the twisted tape increases CHF at a cost of rise in pressure drop. Therefore, designs of twisted tapes which further maximizes cooling capacity while minimizing rise in pressure drop are desired. In this study, the design and fabrication of swirl tubes with innovative twisted tapes is introduced. The conventional twisted tape has the width as same as the inner diameter of the tube, which obstructs fluid flow in the core region. On the other hand, the proposed design has the twisted rail-like tape consisted of two narrow strips spaced out at the core region, which is expected to generate swirl flow near the tube wall to remove vapor bubbles and reduce flow resistance due to the unobstructed flow area in the core region. To validate and optimize the proposed design concept, a set of CFD analysis is performed by varying main design parameters of twisted rail-type tapes. Test specimens with the complex geometry of the rail-type twisted tape are manufactured thanks to recent metal-based 3D printing techniques. Finally, CHF and pressure drop of water-subcooled flow boiling in a swirl tube with various rail-type twisted tape are experimentally investigated.
Co-authors
Hyungdae Kim
(Department of Nuclear Engineering, Kyung Hee University, Yongin-si, Gyeonggi-do, South Korea)
Youngjae Park
(Department of Nuclear Engineering, Kyung Hee University, Yongin-si, Gyeonggi-do, South Korea)
