Research on condensation characteristics of supercritical carbon dioxide in Laval nozzle considering working condition of power cycles

The supercritical carbon dioxide (sCO2) thermal power cycle is a solution for generation IV nuclear energy systems. The potential condensation in the key equipment of the power system poses a serious threat to the safe operation of the system. Aiming at the condensation that may occur inside the sCO2 compressor, this paper numerically simulates the condensation that occurs in a convergent-divergent nozzle. The wet steam model and the homogeneous equilibrium model (HEM) are present and compared with the experimental data. The HEM is used to calculate the influence of the inlet conditions of the fluid into the nozzle and the different expansion rates corresponding to different nozzle shapes on the condensation phenomenon. The results show that the HEM can represent the two-phase flow of carbon dioxide in the nozzle. The nozzle inlet boundary conditions and nozzle expansion rate have an important influence on the condensation characteristics, the former influences the condensation position, while the expansion rate has an influence on the outlet humidity and pressure drop.