Thermal-hydraulic models for the cooling of HTS power-transmission cables: status and needs

An overview of the main peculiarities of the models currently available in literature for the thermal-hydraulic analysis of the cooling of the HTS power transmission cables, mainly in nominal operating conditions, is performed. Several models address specific issues such as the temperature distribution along or across the cables, and their pressure drop, typically with a simplified approach. The verification and validation of the models has not been systematically addressed so far. From the analysis of the available literature, the lack of a general model, capable to address thermal-hydraulic transients for the cooling of the different possible cable designs, with capability to catch both the behaviour of the cable solid components and different cryogens, is highlighted. The main ingredients that such general thermal-hydraulic model should not miss are presented, also based on the know-how on, and comparison to, similar tools for LTS cables for nuclear fusion applications.