Analiza zjawisk termo-hydraulicznych w kablu nadprzewodnikowym typu CICC z centralnym kanałem chłodzącym dr inż. Monika Lewandowska

Plan seminarium Wprowadzenie –Cable in Conduit Conductors (CICC’s) –CICC’s w tokamaku ITER –Istota zjawiska termosyfonu Charakterystyka badanej próbki Opis eksperymentu Wyniki Perspektywy

Cable in Conduit Conductors (CICC’s) Hole Bundle Scheme of the early CICC proposal Modern realizations of CICCs to be applied in magnets for fusion technology

Przekrój typowej żyły kabla nadprzewodnikowego typu CICC

The ITER project International Thermonuclear Experimental Reactor Aim: produce energy from nuclear fusion High magnetic field (11 T) to confine the hot plasma Heavy heat loads on the coils due to neutron flux  CICC’s mandatory!

Central Solenoid: 1152 Nb 3 Sn Strands, 13 T, 45 kA Toroidal Field Coil: 900 Nb 3 Sn Cu Strands, 68 kA, 11.3 T Poloidal Field Coil: 1440 NbTi Strands, < 45 kA, < 6 T CICC’s in ITER

Gravity-buoyancy effect in a dual channel CICC In a vertically oriented dual channel CICC with the coolant flowing downward, power deposition in the bundle region causes the reduction of the flow velocity due to the reduced density of helium. Eventually, the back-flow can occur, leading to quench.

Charakterystyka badanego kabla (ITER TF) Supercond. strands Sub cable Sub-cable wrap Central spiral Final cabling stage Bundle void fraction Cable jacket ø 0.82 mm, 2 μm Cr plating, Cu/nonCu = 1 (2 sc + 1 Cu)×3×5×5 strands + 3×4 Cu core Single layer 70 μm steel foil, ~50% coverage Inner/outer ø 7/9 mm, 30% open surface 6 wrapped sub cables, mm twist pitch Inner/outer ø 40.5/43.7 mm, 316 LN steel

Schemat oprzyrządowania próbki

Fotografie oprzyrządowania próbki

Experimental setup SULTAN = SUpraLeitende TestANlage = Test facility for superconductors Supercritical He: T inlet = 4.5 K or 6.5 K p inlet = 1 MPa = 10 g/s

Typical set of raw data

Results R.Herzog, M.Lewandowska, M.Calvi, M.Bagnasco. C.Marinucci, P.Bruzzone, Helium flow and temperature distribution in a heated dual channel CICC sample for ITER, accepted for publication in IEEE Transactions of Applied Superconductivity We measured and analysed the temperature deviations from the 1D model, which assumes homogenous temperature in every cross section n After a heated region the deviations ΔT disappear exponentially with distance. The magnitude of ΔT is proportional to the heating power per unit length and inversely to the mass flow rate. ΔT max may be readily estimated from the obtained results.

Assessment of the helium velocity in the cooling channel and in the bundle v H was estimated from the time delay between the rising edges of spot heater SHa current and TRa readings.

Friction factor correlations Hole ITER DDD Zanino Bundle ITER DDD Katheder Porous medium D-F Porous medium A R. Zanino, et al., IEEE Trans. Appl. Supercon. 10 (2000) h – spiral height, w – width, g – gap H. Katheder, Cryogenics 34 (1994) 595–598 [ICEC supplement] M. Bagnasco, et al, CHATS AS 2008

Pressure drop and helium velocity in TFS experimental data and simulation

Pressure drop and flow velocities experimental data and final model

Heat transfer in the ITER TF conductor

Stationary two-channel model temperature in the cooling hole temperature in the cable bundle mHmH mBmB ph BH TBTB THTH B.Renard, et al, Evaluation of thermal gradients and thermosiphon in dual channel cable-in-conduit conductors, Cryogenics 46 (2006) Constant thermophysical parameters Analytical solution

Average heat transfer coefficient between bundle and hole C. Marinucci, et al, Analysis of the transverse heat transfer coefficients in a dual channel ITER- type cable-in-conduit conductor, Cryogenics 47 (2007)

Temperature profiles along the sample experimental data and simulation

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