Analysis of Thermal-Hydraulic Gravity/ Buoyancy Effects in the Testing of the ITER Poloidal Field Full Size Joint Sample (PF-FSJS)

Zanino, Roberto; Bruzzone, P.; Ciazynski, D.; Ciotti, Marco; Gislon, P.; Nicollet, S.; Savoldi, Laura

doi:10.1063/1.1774726

Cited by 11 publications

(4 citation statements)

References 10 publications

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“…increase of temperature T 2 upstream from the heated zone, becoming higher than the downstream temperature T 4) which could be associated with the effect of gravity due to the vertical position of the sample (i.e. the thermosiphon phenomenon between the central hole and the annular channel) [9,10].…”

Section: Other Measurementsmentioning

confidence: 99%

Test results on the first 50 kA NbTi full size sample for the International Thermonuclear Experimental Reactor

Ciazynski¹,

Zani²,

Ciotti³

et al. 2004

Supercond. Sci. Technol.

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Within the framework of the R&D studies for the International Thermonuclear Experimental Reactor (ITER) project, the first full size NbTi conductor sample was fabricated industrially and tested in the SULTAN facility (Villigen, Switzerland). This sample (PF-FSJS), which is relevant to the poloidal field coils of ITER, is composed of two parallel straight bars of conductor, connected at the bottom through a joint designed according to the CEA twin-box concept. The two conductor legs are identical except for the use of different strands: a nickel plated NbTi strand with a pure copper matrix in one leg, and a bare NbTi strand with a copper matrix and internal CuNi barrier in the other leg. The two conductors and the joint were extensively tested as regards DC and AC properties. This paper reports on the test results and analysis, stressing the differences between the two conductor legs and discussing the impact of the test results on the ITER design criteria for the conductor and joint. While joint DC resistance, conductors and joint AC losses fulfilled the ITER requirements, neither conductor could reach its current sharing temperature at relevant ITER currents, due to instabilities. Although the drop in temperature is slight for the CuNi strand cable, it is more significant for the Ni plated strand cable.

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Section: Other Measurementsmentioning

confidence: 99%

Test results on the first 50 kA NbTi full size sample for the International Thermonuclear Experimental Reactor

Ciazynski¹,

Zani²,

Ciotti³

et al. 2004

Supercond. Sci. Technol.

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“…S. Nicollet [8] first brought a consistent interpretation of the effect in January 2003 and the experimental results were partly reproduced by a numerical model [9].…”

Section: The Buoyancy-gravity Effectmentioning

confidence: 99%

“…In the simulations, constant mass flow rate, inlet temperature and outlet pressure were assumed as boundary conditions and the power was assumed to be a square wave in space and time fully deposited in the cable region (no power in the jacket). The use of the friction factors as in [11] guaranteed the correct computation of the initial flow repartition, which is a crucial issue and a new ingredient with respect to the previous analysis of the PF-FSJS [9]. The heat transfer coefficient between hole and bundle were assumed constant and equal to 150-200 W/m 2 K (deduced from other thermalhydraulic tests of the PFIS), which is also a new ingredient of the analysis.…”

Section: Numerical Simulationmentioning

confidence: 99%

Results of Buoyancy-gravity Effects in ITER Cable-in- Conduit Conductor with Dual Channel

Bruzzone¹,

Stepanov²,

Zanino³

et al. 2006

AIP Conference Proceedings

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The coolant in the ITER cable-in-conduit conductors (CICC) flows at significant higher speed in the central channel than in the strand bundle region due to the large difference of hydraulic impedance. When energy is deposited in the bundle region, e.g. by ac loss or radiation, the heat removal in vertically oriented dual channel CICC with the coolant flowing downward is affected by the reduced density of helium (buoyancy) in the bundle region, which is arising from the temperature gradient due to poor heat exchange between the two channels. At large deposited power, flow stagnation and back-flow can cause in the strand bundle area a slow temperature runaway eventually leading to quench. A new test campaign of the thermal-hydraulic behavior was carried out in the SULTAN facility on an instrumented section of the ITER Poloidal Field Conductor Insert (PFIS). The buoyancy-gravity effect was investigated using ac loss heating, with ac loss in the cable calibrated in separate runs. The extent of upstream temperature increase was explored over a broad range of mass flow rate and deposited power. The experimental behavior is partly reproduced by numerical simulations. The results from the tests are extrapolated to the likely operating conditions of the ITER Toroidal Field conductor with the inboard leg cooled from top to bottom and heat deposited by nuclear radiation from the burning plasma.

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“…T HE observation of an upward counter flow of helium in the outer annulus of the vertically oriented and top-to-bottom cooled ITER Poloidal Field Coil-Full Size Joint Sample in 2002 [1]- [3] led to closer experimental [4], [5] as well as theoretical [5], [6] investigations of the effect because it may lead to a reduction of the operational margin of the superconductor used in the ITER toroidal field (TF) coils. Since the diameter of the central channel has been reduced from 10 mm to 7 mm, an experimental campaign was launched to investigate the thermohydraulic behavior of the helium flowing in an up-to-date prototype in detail.…”

Section: Introductionmentioning

confidence: 99%

Helium Flow and Temperature Distribution in a Heated Dual-Channel CICC Sample for ITER

Herzog

Lewandowska²,

Bagnasco

et al. 2009

IEEE Trans. Appl. Supercond.

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A spare, 3.5 m long dual-channel cable-in-conduit conductor (CICC) section, made according to the most recent ITER toroidal-field coil design, allowed conducting dedicated thermo-hydraulic experiments in the SULTAN test facility. The sample was heated by eddy-current losses induced in the strands by an applied AC magnetic field as well as by strip heaters mounted on the outside of the conductor jacket. Temperature sensors mounted on the jacket surface, in the central channel and at different radii in the annular region revealed a detailed picture of the temperature distribution at different mass flow rates and heat deposition modes. A clear phenomenological description of the temperature deviations from the one-dimensional expectation emerged during the experiments. The measurement of the flow velocities in the central channel and in the annular region under several heat-load conditions led to further insights.

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Analysis of Thermal-Hydraulic Gravity/ Buoyancy Effects in the Testing of the ITER Poloidal Field Full Size Joint Sample (PF-FSJS)

Cited by 11 publications

References 10 publications

Test results on the first 50 kA NbTi full size sample for the International Thermonuclear Experimental Reactor

Test results on the first 50 kA NbTi full size sample for the International Thermonuclear Experimental Reactor

Results of Buoyancy-gravity Effects in ITER Cable-in- Conduit Conductor with Dual Channel

Helium Flow and Temperature Distribution in a Heated Dual-Channel CICC Sample for ITER

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