The ejector is the key component in a heat-driven ejector refrigeration system

and its performance is of considerable importance to the system efficiency. The limiting operating condition is defined as the working condition when the secondary mass flow rate is equivalent to zero

and the performance under this working condition is important to the ejector working mechanism and application. In this study

experimental apparatus to study the ejector performance under the limiting operating condition was designed and constructed

using R134a as a refrigerant. The effects of the primary flow pressure and ejector back pressure on the back pressure of the converging-diverging nozzle were studied experimentally under the limiting operating condition

i.e.

when the secondary mass flow rate was zero. The experimental results show that both the primary flow pressure and ejector back pressure have considerable influence on the back pressure of the nozzle under the limiting operating condition. The nozzle back pressure decreases with an increase in the primary flow pressure

but increases with an increase in the ejector back pressure. In this study

detailed values were obtained for the lowest evaporating pressure of the system. The findings indicate that the primary flow pressure is in the range of 1.5-3.2 MPa and the ejector back pressure is in the range of 0.66-0.96 MPa. These results can provide guidance for ejector refrigeration system application.