Thermal-hydraulic characteristics of purge gas in a rectangular packed pebble bed of a fusion reactor using DEM-CFD and porous medium analyses

摘要

The thermal-hydraulic characteristics of helium as a purge gas for the removal of the tritium from a spherical packed rectangular pebble bed reactor are studied in this paper using the DEM-CFDand porous medium approaches. Numerical models are developed for the two approaches considering radiation heat transfer, which are validated with the published experimental results. Further, a comparison is made between the porous medium and the DEM-CFD approaches for predicting the thermal and hydraulic characteristics of the helium. The heat transfer behaviour predicted by both the approaches is approximately the same. The DEM-CFD approach can capture the detailed and localized flow behaviour in the presence of pebble, whereas the porous medium approach can predict the average flow characteristics. Further, the effect of the location of the inlet and outlet on the uniformity of the fluid flow in the canister is studied by considering different combinations of inlet and outlet.It is found that the pebble bed with diagonally opposite inlet and outlet configuration has a higher tritium sweeping efficiency as compared to the existing design of the canister with inlet and outlet at the same face.