Scaled validation test for high prandtl number fluid mixed convection between parallel plates

Abstract

The Kairos Power fluoride salt-cooled high temperature reactor (KP-FHR) passive decay heat removal system performance strongly depends on heat transfer characteristics in the reactor vessel’s down comer region. This region is an annular gap where the salt coolant flows downward between the core barrel and reactor vessel before entering the core region at the bottom of the vessel. Kairos Power’s principal safety analysis code, KP-SAM, extrapolates from existing heat transfer correlations for this geometry and applicable flow configurations. Main flow regimes of interest for safety analysis of the KP-FHR, when the system transitions from forced to natural circulation in the vessel upon loss of forced cooling, are the laminar and transition regimes. These regimes are not very well characterized in the literature, so in order to validate the inclusion of appropriate correlations in KP-SAM, scaled separate effects tests are conducted using a test facility that matches the Reynolds, Rayleigh and Prandtl numbers between the prototypical reactor coolant, Flibe, and a surrogate fluid, Therminol VP-1. The specific boundary conditions investigated are both symmetric heating and asymmetric heating. The data generated from this test serves to develop a validated heat transfer correlation for the laminar and transition regimes for implementation in KP-SAM, in support of safety analysis and licensing of the KP-FHR.