Numerical study of coupled Heat Transfer between Primary and Secondary sides of Helical Coiled Tube Steam Generator for Liquid Metal Fast Reactor

[Background] Helical Coiled Tube Steam Generator is the core equipment for energy transfer in Liquid Metal Fast Reactors, which transfers the heat released from the core on the primary side to the work mass on the secondary side, Generates Steam and pushes the turbine to do work, and the stability and safety of its operation have a crucial impact on the operational safety, economy and reliability of Nuclear Power plants. This paper proposes a numerical simulation method using computational fluid dynamics software for the coupled heat transfer calculation of two-phase fluids on the primary and secondary sides of the Helical Coiled Tube Steam Generator of a Lead-bismuth Fast Reactor. [Purpose] Based on the experimental data, the calculation reliability of the primary side heat transfer and the secondary side heat transfer of the model in this paper are verified respectively. [Methods] First of all, a three-dimensional numerical model of coupled primary and secondary heat transfer in a Liquid Metal Fast Reactor Helical Coiled Tube Steam Generator is constructed, and the correlation equations of Liquid Metal and water-vapor variability are established based on the OECD Physical Property Handbook and the NIST database, Then, the Lee phase transition model is used to calculate the mass transfer between the two phases during the evaporation of water-vapor on the secondary side. Finally, taking the Lead-bismuth Fast Reactor as an example, the coupled heat transfer characteristics between the primary and secondary sides of the steam generator under different primary-side inlet parameters are investigated and compared with the conventional Water Reactors. [Results] The results show that, under the same conditions, compared with the traditional Water Reactor, when Lead-bismuth Liquid Metal is used in the primary side, the wall heat flux between the primary and secondary sides is significantly increased, and the peak heat flux can reach 1439.97 kW·m-2, which is 5-6 times higher than that of the corresponding value of the Water Reactor, which leads to a significant intensification of the vapor evaporation process in the tube of the secondary side, and the volumetric vapor volume fraction rate rises sharply; at the same time, the along-track heat flux distribution between the primary and secondary sides is more heterogeneous, which leads to an increase of the vapor volume fraction rate. [Conclusions] At the same time, the heat flux distribution between the primary and secondary sides is more uneven, and the relative deviation of the heat flux distribution along the heat flux is 3-4 times larger than the corresponding value of Water Reactor. With the increase of the inlet Lead-bismuth temperature of the primary side from 350 ℃ to 450 ℃, the wall heat flux between the primary and secondary sides increases, and the corresponding peak heat flux increases from 950.7 kW·m-2 to 1439.97 kW·m-2, which is about 1.5 times, and at the same time, the distribution of the along-range heat flux between the primary and secondary sides is more inhomogeneous, and the inhomogeneity is increased by 20 %.