Thermal Mixing Performance of Mixing Structure at Reactor Outlet of HTR-PM under Complex Conditions

In order to investigate the effects of bypass flow and power change and deviation on radial temperature difference of the helium flow entering the steam generator, model experiments and simulation calculations are proposed to evaluate the Thermal Mixing Performance (TMP) of the thermal mixing structure at Pebble-bed Module High Temperature gas-cooled Reactor (HTR-PM) core outlet. The experiments on Test Facility - Hot Gas Mixing (TF-HGM) are carried out to observe the influences of bypass flow and reactor power deviation. Simulation calculations are conducted for the mixing structure of TF-HGM and HTR-PM. According to the results of experiments and CFD simulation, the maximum radial temperature difference at the outlet of the mixing structure fulfils the requirement by steam generator, under all considered conditions. In addition, the TMP obtained by the temperature difference between main flow and bypass flow is suitable for the experiment and the simulation results while the new definition of TMP integrating specific heat, flow rate, inlet position and thermal uniformity needs further improvement.