Optimization of Enhanced Steam-Ejector Applied to Steam Jet Refrigeration

Abstract

Abstract Ejectors are used for a wide range of applications. Refrigeration systems have, a long established history. Ejector refrigerators working on steam or halocarbon refrigerants provide a high level of flexibility. Ejector can also be used in solar-powered refrigeration systems and absorption-refrigeration systems. There are very few comprehensive theoretical studies even though several models for ejectors in literature. A new ejector theory was developed by Munday and Bagster (1977). This theory depends on the assumption of two discrete streams, the motive stream and the secondary stream. The two streams maintain their identity down the converging duct of the diffuser. At some section the secondary flow reaches sonic velocity. The shocking and mixing occur at the very end of the converging cone resulting in a transient supersonic mixed stream. There is no supersonic deceleration and a shock takes place immediately on mixing. The mixed stream will shock to the subsonic, found by the intersection of the Fanno and Rayleigh lines. After that the stream is brought to near zero velocity in the diffuser. In the present work this theory is used as a basis, in order to develop a computerized model of ejector with particular reference to steam-ejector at various operating conditions. The results are compared with available from the literature experimental data. Also a parametric study is conducted in order to reveal the influence of the various parameters on the performance of the steam jet refrigeration.