Hydraulic characterization of conductor prototypes for fusion magnets

Abstract

Forced flow HTS conductors designed for the Winding Demonstrator (WD) or EU DEMO Toroidal Field (TF) and Central Solenoid coils consist of several CroCo or twisted stack monolithic strands, embedded in a stainless steel jacket. Such type of conductors have never been tested for pressure drop. Cable-in-Conduit conductors for the DEMO TF coils designed by ENEA have two low-impedance cooling channels, separated from the cable bundle by flat spirals, with the inner/outer diameter of about 5/7 mm. Experimental pressure drop data for such small spiral ducts are also unavailable yet. To fill this gap, four dedicated short samples, namely dummy conductors with the layout similar to the DEMO HTS or WD conductors and a small spiral-walled pipe have been prepared and tested for pressure drop using demineralised water at 2–3 different temperatures. The tests using water have been performed covering the same range of Reynolds number experienced by the supercritical He at operating conditions typical for DEMO coils. The experimental data have been used to develop experimental friction factor correlations for the considered ducts, which could be utilized in future thermal-hydraulic studies of the DEMO coils or WD.