Heat Transfer Coefficient Measurement in Single Channel Cable-in-Conduit Conductor

Cable-in-conduit conductors (CICC) compose superconducting magnets of tokamaks and are cooled with 4 K supercritical helium forced flow, to provide efficient heat removal and thermal stability of the superconducting state. Nowadays, thermal couplings between fluid and solids are ill-characterized for such cables. We consequently measured global heat transfer interphase coefficients at macro scale. An experimental set-up associated with an inverse method and a direct three temperatures thermal-hydraulic model have been developed to obtain representative data. Transient experiments of forced flow with heat pulses imposing thermal disequilibrium between fluid and solids have been performed. Results are correlated to actual geometric properties obtained from 3D tomography. 1D three temperatures model of the two phases (bundle/nitrogen) along with the jacket, thermally coupled by convection is solved using finite volume method with an implicit and upstream scheme. Results are compared to available literature data.