Abstract: The two-stage ejector (TSE), as a device with the enhanced performance by taking full advantage of the dissipated momentum in the mixing chamber, has significantly improved the entrainment ratio compared to the traditional single-stage ejector (SSE). However, limited research has been focused on the TSE in refrigeration system. Herein, a new TSE used in the refrigeration system was studied, as well as its performance according to computational fluid dynamics (CFD). Meanwhile, the $ k-\omega $ SST turbulence model and R134a refrigerant were adopted, the performance of TSE under different working pressure, injection pressure and condensing pressure was simulated and compared with that of the SSE under the same working condition. The results show that compared with the SSE, the entrainment ratio of the TSE increases up to 57.50%, whereas the critical condensing pressure may reduce by 18.98% or less.
Keywords: two-stage ejector (TSE); single-stage ejector (SSE); computational fluid dynamics (CFD); entrainment ratio; critical back pressure