Calculations of pressure drop and mass flow distribution in the toroidal field model coil of the ITER project

Abstract

In preparation of the ITER FEAT project, a superconducting toroidal field model coil (TFMC) including 10 parallel pancakes of between 72.2 and 82.0 m long cable-in-conduit conductor (CICC) has been built and has to be tested at FZK. A series of preliminary tests were performed at room temperature and in nitrogen at both CEA-Cadarache and Ansaldo. The tests aimed to assess the thermohydraulics of this coil and specifically to address the pressure drop and the friction factor of the dual channel CICC in a range of Reynolds numbers relevant to the TFMC. These measurements are compared with the predictions which include a hydraulic description of the joint region whose contribution to the total pressure drop is non-negligible. The mass flow distribution between the bundle region and the central channel will be calculated for the cable as well as for the joint region. Measurements on the central solenoı̈d model coil (first layer of inner module and insert coil) in normal operating conditions with supercritical helium are presented. They are in good agreement with the calculations performed from the previously validated correlations. A description of the mass flow imbalance between the TFMC pancakes at low temperatures in helium is done. The major influence of the central spiral is confirmed, since two types of spirals have been included in the TFMC pancakes. This distribution varies as a function of the total mass flow of the analysed hydraulic circuits (TF and CS) of ITER–FEAT.