DOI: 10.14457/tu.the.2016.679
title: Experimental study and performance assessment of steam ejector refrigeration system

description: In this thesis, a 1 kW experimental steam ejector refrigerator was designed and constructed. Two main studies were conducted on this testing unit. The first study is a comparison of conventional and CRMC ejector performance used in a steam ejector refrigeration system. The second study is the performance of the experimental steam ejector refrigerator based on the alternative analysis.In the first study, the performances of a steam ejector design based on the constant rate of momentum change (CRMC) and conventional ejector were tested in an attempt to compare their performance. Two different ejectors were designed and constructed: conventional ejector with throat diameter of 13.4 mm, and a CRMC ejector with throat diameter of 13.4 mm. Another conventional ejector with throat diameter of 19 mm was used as benchmark of the newly designed conventional ejector. They were designed to be easily equipped with the 1kW experimental ejector refrigerator. The boiler saturation pressure varied from 130°C to 140°. The evaporator saturation temperature was fixed at 7.5°C. The results show that at the same operating condition and the same ejector area ratio (the area ratio of nozzle throat to ejector throat), the CRMC ejector provided higher mass entrainment ratio than the traditional ejectors (up to 40%) while the critical condenser pressure remained the same.In the second study, the performance of a steam ejector refrigerator was analysed based on an “alternative analysis”. The alternative analysis reflects the actual operation of an ejector refrigerator unlike the traditional analysis. In this analysis, the evaporator saturation temperature associated with cooling load was varied while the boiler saturation temperature and the condenser pressure were fixed. From this test, the critical evaporator temperature was determined. The critical evaporator temperature is the lowest point at which the ejector still operated under choked flow conditions. Various operating conditions and primary nozzles were implemented. It was found that variation in operating conditions and the nozzle throat diameters significantly affected the critical evaporator temperature. Variation of the condenser pressure and the primary nozzle exit Mach number based on alternative analysis provided the same effect. The mass entrainment ratio in the chocked flow condition is independent of the condenser pressure and the primary nozzle exit Mach number. Either increasing the condenser pressure or decreasing the primary nozzle exit Mach number, causes the critical evaporator temperature to decreases and vice versa. Variation of the boiler saturation temperature and the primary nozzle throat diameter affect the mass flow of primary fluid. Increasing the boiler saturation temperature or the primary nozzle throat diameter, causes the mass flow of primary fluid to increases. When the primary fluid mass flow is increased, the critical evaporator temperature is reduced. Meanwhile, the mass entrainment ratio in the chocked flow condition also decreases. However, if the primary fluid mass flow is increased to a certain value, the critical evaporator temperature does not decrease as expected