Numerical simulation of heat transfer characteristics of supercritical liquid hydrogen through triangular U-tube in moderator

In this study, the heat transfer characteristics of supercritical hydrogen in triangular U-tubes with different radius were investigated. In order to compare the heat transfer capacity of triangular U-tubes, and to explore the heat transfer characteristics of supercritical liquid hydrogen inside them, a three-dimensional numerical simulation was carried out by Fluent. The unstructured grid and RNG k-ε turbulence model were used to encrypt the grid. Meanwhile, the grid independence and the effectiveness of the turbulence model are verified. The T_w, T_f and Nu along the triangular U-tube at different q and Re were compared. The result shows that T_w, T_f and Nu increase with the increase of q and Re. The change of Re was found to be largest for Nu. The effect of secondary flow on Nu was similar to the entrance effect of upstream straight pipe, and the effect of secondary flow on Nu was slightly larger than the entrance effect. This work provides a useful technical guidance for thermal design and thermal management of neutron source and target station, as well as novel ideas for flow and heat transfer of supercritical liquid hydrogen in U-tube.