(193b) Investigating Air Thermal-Hydraulic Behavior Under Natural Convection By Non-Uniform Heating in a Plenum-to-Plenum Facility

Obtaining precise results and new benchmark data for studying the gas thermal behavior flowing within the very high temperature gas cooled reactors (VHTGRs) significantly affects the design and safety operations of these reactors. The two candidates classified as VHTGRs are prismatic modular reactors (PMRs) and pebble bed modular reactors (PBMRs). Therefore, a unique Plenum-to-Plenum facility (P2PF) has been designed and manufactured as a distinguished outstanding representation for the gas flow in the prismatic modular reactors (PMRs) core during loss of flow accidents (LOFA). This facility consists of two plenums connected by vertical dual channels in which one channel is heated and the other channel is cooled to create natural circulation between the two plenums. The objective of the current study is to understand and visualize the air thermal behavior at different axial positions along the hot channel for various heating profiles by integrating advanced measurement techniques. Results show that the air temperature and velocity along the heated channel depends on the hot channel surface temperature distribution. Moreover, flow reversal (back-mixing) is observed at the top of the hot channel leading to the formation of eddies and turbulence which significantly affect the air thermal behavior. The obtained findings will provide valuable data for further investigations by computational fluid dynamics (CFD).