1.2 ObjectivesThis thesis studies the design of the proposed two-stage ejector type annular secondary at the second stage, without changing the area ratio (Ar) of the ejector, to investigate the performance of ejector refrigeration system and the gas/gas ejector application using the validation of the CFD and experimental results compared with those of the single-stage ejector. The two most important parameters used to analyze the performance of an ejector are the entrainment ratio (Rm) and critical back pressure (CBP).