Transversal heat transfer in the cable-in-conduit conductor for the Wendelstein 7-X magnet system

Abstract

In the Helitex test facility of KfK/ITP experimental investigations were performed on the transversal heat transfer in the cable-in-conduit conductor (CICC) for the Wendelstein 7-X magnet system. Additionally, a theoretical method was developed to determine the transversal heat transfer coefficient in the CICC. This method is based on the numerical analysis of two-dimensional heat conduction in the jacket. It shows that the transversal heat transfer from the jacket to the flow channel (helium plus strands) cannot be accurately described either by pure heat conduction or by pure convection heat transfer. A new model was developed which takes into account heat conduction and heat convection simultaneously. For the W7-X conductor considered, the equations of heat transfer between the jacket and helium and between the jacket and the strands were optimized.