Numerical simulations of molten salt pebble-bed lattices

The study found that the different lattice geometries have a significant impact on the heat transfer characteristics. The SC lattice has a simplified flow that minimizes pressure-drop and Nusselt number. The BCC and FCC lattice have a complicated flow structure resulting in an order of magnitude higher pressure-drop and almost double the Nusselt number. It was concluded that heat transfer characteristics in a random pebble-bed would be highly sensitive to the mixing, and thus turbulent heat transfer, along the flow path. It was also found that while an interstitial gap allows heat transfer characteristics to be replicated, the pressure loss is significantly lower, while the computational costs increase. Correlations available in the literature (developed primarily for HTGRs) have a mixed performance in prediction of the Nusselt number. The result suggests that new experimental efforts are necessary to develop correlations that pertain to FHR conditions.