CFD simulation of two-phase ejector performance influenced by different operation conditions

In this paper, the influence of temperature phase change on two-phase ejector is investigated by the computational fluid dynamics (CFD) technique. The working fluids used in this research are LNG as primary fluid and BOG as secondary fluid. The transient behavior in the two-phase ejector is simulated to find the optimal operation conditions for higher ejector performance. The axial velocity, pressure and temperature, entrainment ratio, heating coefficient, volume fractions of gas and liquid are obtained under different operation conditions. The predicted values by CFD simulation prove to be in good agreement with on-site test data. Phase change has a significant effect on the performance of LNG-BOG ejector. The results show that entrainment ratio increases with increasing LNG inlet velocity and decreasing mixture outlet pressure. Too high BOG inlet and mixture outlet pressure can result in abnormal ejection. For the specific two-phase ejector described in this paper, the optimal ejection performance is obtained under the conditions with LNG inlet velocity of 11-12 m/s, BOG inlet pressure of 0.101-0.507 MPa and mixture outlet pressure of 0.101-0.304 MPa. This study may provide a beneficial reference for good performance of LNG-BOG ejector and may be helpful for further applications in LNG transportation.