Fig. 2. Mollier’s chart of an ejector.
The experimental results and analysis, provided in , indicated that this hypothetical area was not constant but varied with the operating conditions. Munday and Bagster also suggested that the mixing process begins after the secondary flow chokes. This mixing causes the primary flow to be retarded whilst secondary flow is accelerated. By the end of the mixing chamber, two streams are completely mixed and the static pressure was assumed to remain constant until it reaches the throat section (iv). The pressure in the mixing chamber was a function of primary fluid, secondary fluid and the back pressure of ejector. Due to a high-pressure region downstream of the mixing chamber’s throat, a normal shock of essential zero thickness is induced (v). This shock causes a major compression effect and a sudden drop in the flow speed from supersonic to subsonic. A further compression of the flow is achieved (vi) as it is brought to stagnation through a subsonic diffuser.
However, it should be noted that the test was not carried out directly in a refrigeration application. Constant-area mixing ejector was used with entire supersonic regime. Not only the experimental investigation, but some researchers tried to explain the flowing and mixing processes through an ejector by using the Computational Fluid Dynamics (CFD) software package. Recently, with the rapid development of the computer and its resources. Models are 3-D flow inside the R245 ejector. In this study, the compressible real gas model was applied on the large numbers of grid elements. The results provide the reliable simulated insight observation of the flow process happening inside an ejector, including the existence of the expanded converging duct of primary fluid and the thermodynamics shock wave. There are several parameters used to describe the performance of an ejector. For refrigeration applications, the most important parameters are ‘an entrainment ratio’ and ‘a pressure lift ratio’: