Numerical Study Of The Performance And Optimization Of A Vane-Type Bubble Separator

Xenon and Krypton,which are important neutron poison,are generated by liquid fuel salt in ThoriumMoltenSaltReactor when it is operating.So,in order to keep the reactor stabilize and the availability of thermal neutron,it is necessary for TMSR to separate the fission gas from the fuel salt continuously.Studies have illuminated that the vane-type bubble separator designed by Oak Ridge National Laboratory appears the advantages of simple structure and high separation efficiency.But as a result of no details or key parameters is published,numerical study on the flow field,pressure profile and the bubble motion have been conducted in this article to explore the mechanism of this vane-type bubble separator and to support the research on the molten salt reactor in our country.The three dimensional geometry model of the fluid domain is established,and then the separating process of the two phases is simulated by CFD software Fluent and CFX.The appropriate grid number,turbulence model and multiple phase model are determined by the mesh independent study and the comparison with the experimental date,respectively.Based on the calculating of the flow field distribution and the force on bubbles,the trajectory and the coalescence of the bubbles can be inferred,which will illuminated the mechanism of vane-type bubble separator.On the basis of this,various volume flow rate,outlet pressure,bubble size and separating length have been studied to explore the primary factor impacting the separation efficiency,and structure optimization has been conducted on the vane number,impeller length,vane outlet angle,trailing edge line and hub shape to determine the optimized dimensions.At last,different continuous phase mediums with various viscosities and densities are conducted to depict the impact of the medium physical parameters.And molten salt with actual physical parameters is regarded as the working medium to validate the actual effect of the vane type separator as well as to support the reliability of air-water experiment study.The simulation results demonstrate that,only RSM model or higher order turbulence model can simulate the flow field in the separator well;it lead to form a steady air core in the center of the sparator that,the bubbles in the separator bear higher centripetal force than centrifugal force and meet thecoalescence requirements;flow rate,bubble size,dimensional parameters,separator length,fluid physical parameters etc.have great impact to the separation efficiency.