Study On Simulation Optimization And Application Of Steam Injector With Auxiliary Injection Inlet

This paper studies the steam ejector,which attempts to improve the performance of the ejector by adding an auxiliary entrainment inlet in its low pressure region to use its pressure potential energy,and discusses the application method of this new structure ejector in practical industry.In this study,the steam ejector with auxiliary entrainment inlet was initially optimized from the three aspects of the position,width,and working pressure of the auxiliary entrainment inlet by using the CFD method,detailed analysis and discussion are made from the mass flow rate of the ejector inlet and outlet,the pressure field and the velocity vector field inside the ejector.The results show that adding an auxiliary entrainment inlet in the low pressure region can indeed improve the performance of the ejector,and it has an important effect on the internal flow field of the ejector.The auxiliary entrainment inlet has an optimal position ratio Lb/Lm=1.10 and an optimal width w=4mm corresponding to the optimal entrainment performance of the ejector,which can be increased by 2.7%compared with the traditional ejector;Based on the determination of the optimal position and width of the auxiliary entrainment inlet,increasing its working pressure Pa can effectively avoid internal backflow.When the working pressure is 37kPa,the mass flow rate of the auxiliary entrainment inlet reaches the maximum,and the ejector outlet mass flow rate increases by approximately 15.5%.Subsequent simulations find that increasing the angle of the diffuser can move the position of the shock wave upstream,which will significantly affect the performance of the auxiliary entrainment inlet.Therefore,based on the preliminary optimization,the position,width and working pressure of the auxiliary entrainment inlet have been further optimized in this paper by combining the influencing factor of the angle of the diffuser.The study finds that there is an optimal auxiliary entrainment inlet position at each difuser angle,and corresponds to a maximum auxiliary entrainment inlet mass flow rate.When the diffuser angle is 10°,the mass flow rate reaches the maximum value,and the corresponding optimal position at this time is L=1mm.Compared with the results obtained from the preliminary optimization,the mass flow rate of the auxiliary entrainment inlet can be increased by about 55.1%,and the entrainment ratio can be increased by 4.1%compared with the traditional steam ejector;The width of the auxiliary entrainment inlet is less affected by the angle of the diffuser,no matter how the angle changes,the optimal width is always 4mm;When the structural parameters of the diffuser and the auxiliary entrainment inlet are in the optimal combination,re-increasing the working pressure Pa of the auxiliary entrainment inlet has the same trend as the preliminary optimization.With Pa=35kPa as the node,when the working pressure is less than 35kPa,the auxiliary entrainment inlet mass flow rate and the ejector outlet mass flow rate are greater than the results of the preliminary optimization;When the working pressure is greater than 35kPa,the auxiliary entrainment inlet mass flow rate and the ejector outlet mass flow rate are less than those obtained by the preliminary optimization.According to the working principles of a variety of practical industrial systems where steam ejectors can be used at present,these systems can be divided into two types:multi-stage pressure drop and non-multi-stage pressure drop,and combined with the research results of this paper,it is found that the method of improving the performance of the ejector by increasing the working pressure of the auxiliary entrainment inlet can only be applied to systems with multi-stage pressure drop.For systems that do not have a multi-stage pressure drop,the pipeline connected to the auxiliary ejection inlet can only be the same as the secondary flow inlet,and the effect of improving system efficiency is small;For systems with multi-stage pressure drop,the auxiliary entrainment inlet can be connected to a pipeline with a pressure between the secondary flow inlet and the ejector outlet,and the efficiency of the system can be greatly improved.