Thermal-hydraulic analysis of superconducting cables for energy applications with a novel open object-oriented software: OPENSC2

Abstract

Super-conducting cables are an enabling technology for energy applications such as large magnetic-confinement nuclear fusion machine, and a promising key player in the power transmission of the next future, both in AC and DC conditions. While the thermal–hydraulic analysis of forced-flow superconducting cables for fusion application can only rely on commercial or proprietary numerical tools, such kind of tools for power transmission cables are not even available. Within the framework of Open Science, set as a priority by the European Commission in Horizon Europe, the novel software OPEN Super Conducting Cables (OPENSC2) has been developed to grant the entire research community the possibility to simulate thermal–hydraulic transients in forced-flow superconducting cables for energy applications. A Test-Driven Development has been adopted for the OPENSC2 within an object-oriented approach. Following the TDD approach, three test cases are considered of paramount interest for the OPENSC2 development, deriving the set of characteristics that the target object-oriented tool should comply with, and namely: 1) a heat slug propagation along an ITER-like 2-region cable-in-conduit conductor, with a thousand of mm-size low-critical-temperature superconducting (LTS) strands, cooled by supercritical helium (SHe); 2) the heat diffusion across the cross section of a twisted-slotted-core cable-in-conduit conductor, with high-critical-temperature (HTS) superconducting tapes, for fusion application, cooled by SHe and 3) the nominal operation of a single-phase HTS High-voltage, Direct Current power cable, with a 2-cryostat configuration and 2 different fluids adopted as primary coolant and thermal shield. In the object-oriented OPENSC2 the class “conductor” is defined, where each Conductor Object (CO) is the combination of different lower-level objects (both fluid and solid components) instantiated by the class. The choice of each component drives the automatic selection of the appropriate physical equation(s) in the code, as well as the possible interactions between them. Thermo-physical properties of different materials and cryogens can be attributed to the components of a conductor objects, taken form open datasets. A user-friendly GUI allows setting and monitoring the simulations while running. The software is tested in the three case studies targeted in the TDD, to show eventually how it allows modeling the three test cases presented here. The Verification and Validation of the CO methods performed through benchmarks against the 4C code is also presented and discussed.