1.3 Scopeofwork1.3.1 Design of two-stage ejector (TSE) type annular secondary at the second stage in an ejector refrigeration system and the gas/gas ejector system.1.3.2 The performance investigation using the CFD for comparing the TSE with the SSE in terms of entrainment ratio (Rm) and critical back pressure (CBP).1.3.3 The CFD methods and algorithms to solve and analyze the systems involving fluid flows were applied using the commercial software GAMBIT 2.3 and FLUENT 6.3.1.3.4 The TSE refrigeration system was analyzed using generator temperatures between 100 and 130 °C and evaporator temperatures between 0 and 15 °C.1.3.5 The TSE gas/gas ejector system was analyzed using primary inlet pressure between 4 and 5 bar and secondary inlet pressure between 0.5 and 1.0 bar.1.3.6 The experimental results of TSE were compared with the results of SSE in the gas/gas ejector system, and validated with the CFD results.