The effects of superheated refrigerant on ejector performances

Ejector-based refrigeration system using low-grade thermal energy has been a promising technology in these days, research shows that superheated refrigerant can improve system performance. In order to investigate the relationship between superheated refrigerant and ejector performance deeply, Computational Fluid Dynamics (CFD) technique was adopted to investigate the phenomenon using R134a as refrigerant, for detecting the effect of primary flow temperature on entrainment ratio, finding out three operational mode of ejectors in different back pressure conditions and analyzing the relationship between superheated refrigeration and phase transition. All the works are aimed at finding optimum working conditions. The results indicated that the optimum entrainment ratio is 0.2489, when the primary inlet conditions is 76°C refrigerant (superheated 30°C) with fixed secondary inlet and ejector outlet. The entrainment ratio improvement is 59.65% compared with initial set (76°C saturation refrigerant). So the high performance ejector should operate in critical mode with maximum entrainment ratio and proper superheated primary flow.