Experimental investigation on the malfunction characteristics of the two-phase ejector in a typical enhanced refrigeration system

In this paper, experimental research was conducted to explore ejector malfunctions caused by varying structural and operating parameters in the ejector outlet split ejector refrigeration system. Effective methods and strategies to mitigate ejector failure were proposed. The results indicated that inappropriate structural parameters led to ejector failure or instability. A smaller nozzle throat diameter and excessively large or small NXP values caused entrainment malfunction but not obvious pressure lift malfunctions. Conversely, a smaller mixing section diameter resulted in pressure lift malfunctions. The effect of the operating parameters on mass entrainment failures or instability was discussed. Smaller electronic expansion valve openings led to significant mass entrainment issues, and the ejector's instability became more pronounced with higher evaporator heat loads. The sensitivity of the electronic expansion valve opening to causing ejector malfunctions varied with different nozzle throat diameters. Throat diameters of 0.7 mm and 0.9 mm corresponded to TOP values of 10 % and 5 % for ejector failure, respectively. Strategies to address ejector entrainment malfunction or instability were studied. Increasing the electronic expansion valve opening effectively suppressed ejector failure, while merely adjusting compressor speed did not. A combined approach of increasing compressor speed and electronic expansion valve opening quickly resolved ejector malfunctions.