Performance analysis of a two-stage ejector in an ejector refrigeration system using computational fluid dynamics

In this study, computational fluid dynamics (CFD) was used to investigate the performance of the steam ejector used in refrigeration systems to increase operational flexibility and COP. A 2D-axisymetric model of a two-stage ejector (TSE) was developed and its performance was compared to that of the commonly used single-stage ejector. The SST k-omega (k-omega-sst) model was applied as a turbulence model. In the simulation, the TSE was analyzed using generator temperatures between 100 and 130 degrees C and evaporator temperatures between 0 and 15 degrees C, as in a previous study. The CFD simulation results showed that the TSE provided high entrainment ratios up to 77.2% while showing a marginal decrease in the critical back pressure up to a maximum value of 21.9%. Therefore, it can be concluded that the TSE can significantly benefit refrigeration systems requiring high refrigerating capacity while maintaining a slightly low condensing pressure.