Numerical Study of Liquid Metal Turbulent Heat Transfer in Cross-Flow Tube Banks

Heavy liquid metals (HLM) are attractive coolants for nuclear fission and fusion applications due to their excellent thermal properties. In these reactors, a high coolant flow rate must be processed in compact heat exchangers, and as such, it may be convenient to have the HLM flowing on the shell side of a helical coil steam generator. Technical knowledge about HLM turbulent heat transfer in cross-flow tube bundles is rather limited, and this paper aims to investigate the suitability of Reynolds Average Navier–Stokes (RANS) models for the simulation of this problem. Staggered and in-line finite tube bundles are considered for compact ( a = 1.25 ), medium ( a = 1.45 ), and wide ( a = 1.65 ) pitch ratios. The lead bismuth eutectic alloy with Pr = 2.21 × 10 − 2 is considered as the working fluid. A 2D computational domain is used relying on the k − ω Shear Stress Transport (SST) for the turbulent momentum flux and the Pr t concept for the turbulent heat flux prediction. The effect of uniform and spatially varying Pr t assumptions has been investigated. For the in-line bundle, unsteady k − ω SST/ Pr t = 0.85 has been found to significantly underpredict the integral heat transfer with regard to theory, featuring a good to acceptable agreement for wide bundles and Pe ≥ 1150 . For the staggered tube bank, steady k − ω SST and a spatially varying Pr t has been the best modeling strategy featuring a good to excellent agreement for medium and wide bundles. A poor agreement for compact bundles has been observed for all the models considered.