Computational investigation into heat transfer coefficients of randomly packed pebbles in flowing FLiBe
Highlights•CFD study for heat transfer characteristics of FLiBe in Molten Salt Reactor core.•LES and RANS comparisons of heat transferring pebbles in flowing FLiBe.•Statistical distribution of pebble heat transfer coefficient due to random packing.•Development of a heat transfer correlation for randomly-packed pebbles in FLiBe.AbstractUsing CFD simulations, this study presents: (1) LES and RANS comparisons for a unit cell geometry of heat transferring pebbles in flowing FLiBe; (2) statistical distributions of pebble heat transfer coefficients due to the random packing; (3) development of a heat transfer coefficient correlation for randomly-packed heat transferring pebbles in flowing FLiBe in the representative Fluoride High-temperature Reactor (FHR) operating condition; and (4) comparison of the developed heat transfer coefficient correlation with existing ones obtained in different fluids and pebble sizes. The LES and RANS comparison has shown that the k-ω Shear Stress Transport (SST) with low Reynolds number approach performance gives the best result in comparison to the two eddy-viscosity based k-ε and k-ω SST models.The statistical distribution of pebble heat transfer coefficients due to random packing has been quantified; random arrangements of pebbles result in non-negligible uncertainties in heat transfer coefficients following normal distributions. This uncertainty needs to be accounted for fuel temperature prediction in reactor design and analyses. A Nusselt number correlation for the randomly packed heat transferring pebble in flowing FLiBe has been computationally developed: Nu = 0.016Re0.72Pr0.31.
بررسی محاسباتی بر روی ضرایب انتقال حرارت از سنگریزه به صورت تصادفی در FLiBe جریان