Numerical investigation of flow characteristics and packing structure of binary-sized pebble flow in a circulating pebble bed

MQ Wu and N Gui, PROGRESS IN NUCLEAR ENERGY, 150, 104312 (2022).

DOI: 10.1016/j.pnucene.2022.104312

The pebble size is one of the factors affecting the flow characteristics of pebble-bed HTGRs. The binary-sized circulating pebble flow is investigated from the perspective of flow behaviors and packing structure. The discharge characteristics including discharge number and volume discharge rate, which are closely related to the equilibrium of the HTGR pebble bed, are explored. The results show that the proportion of each type of pebble maintains stability during circulation when the loading ratio is consistent with its number ratio (NR). From the qualitative and quantitative analysis of the retention, it is found that the size difference has no significant effect on the retention, and it takes nearly 1.7 ideal circulating periods for initially loaded pebbles to flow out in all cases. In addition, the actual retention period also shows no difference. Furthermore, the packing structure is investigated through arc-based analysis of porosity and packing fraction, number distribution, and coordination number.

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