Analysis of steady state thermal-hydraulic behaviour of the DEMO divertor cassette body cooling circuit

Highlights: • Thermal-hydraulic study of DEMO divertor cassette body cooling system. • Adoption of a computational fluid-dynamic approach based on finite volume method. • Comparative study on both water and helium cooling options. • Assessment of spatial distributions of pressure drop, flow velocity and temperature. • Analysis of an improved layout, leading to significant performances enhancement. - Abstract: Within the framework of the Work Package DIV 1 – "Divertor Cassette Design and Integration" of the EUROfusion action, a research campaign has been jointly carried out by ENEA and University of Palermo to investigate the thermal-hydraulic performances of the DEMO divertor cassette cooling system. A comparative evaluation study has been performed considering the two different options under consideration for the divertor cassette body coolant, namely subcooled pressurized water and helium. The research activity has been carried out following a theoretical-computational approach based on the finite volume method and adopting a qualified Computational Fluid-Dynamic (CFD) code. CFD analyses have been carried out for the considered options of cassette body cooling circuit under nominal steady state conditions and the pertaining thermal-hydraulic performances have been assessed in terms of overall coolant thermal rise, coolant total pressure drop, flow velocity and pumping power, to check whether they comply with the corresponding limits. Results obtained are reported and critically discussed.