Numerical investigation on the bubble separation in a gas-liquid separator applied in TMSR

The fission gas removal system plays a critical role in the development of the Thorium Molten Salt reactors. An axial gas-liquid separator is adopted in the gas removal system. To predict the bubble trajectories in swirling flow is essential for designing such gas-liquid separator, since the separation efficiency is closely related to the bubble trajectory. In this paper, we proposed a numerical method to predict the bubble motion. This method is a modified Lagrangian approach in that the velocity of the continuous phase is obtained by approximating the velocity profiles from CFD. Combing the known velocity distribution with explicit mathematical expression and the force model for a single bubble, a mathematical model to calculate the bubble motion is well posed. Calculations with various bubble sizes and Reynolds numbers were carried out. By comparing the simulation results with the experimental data, we concluded that the numerical results agree well with the experimental data. The maximum error of the separation length is less than 10%, which is accurate enough for the determination of the dimension of the separator.