Experimental study on key geometric parameters of an R134A ejector cooling system

• An ejector cooling system by using R134a and air-cooled condenser was built.
• The influence of 3 geometric parameters on ejector performance was studied.
• Optimal geometric parameters and dimensionless parameters between them were obtained.

Ejector geometric parameters largely depend on condensation pressure of working fluids. The area ratio of the ejector is much smaller than that of ejector cooling systems using lower condensation pressure working fluids when R134A is used as working fluid. Consequently, it deserves to study other key geometric parameters when using this working fluid. In this paper, the ejector cooling system with R134A was established first. Next, the influence of three geometric parameters such as nozzle exit position, the length of constant-area section and diverging angle of primary nozzle on the ejector performances was investigated via experimental methods. The results showed that the influence of nozzle exit position on ejector performance is evident as compared to the other two. Moreover, optimal geometric parameters and dimensionless parameters between them were obtained and compared to those of lower condensation pressure systems. This provided simple but practical ejector design guidelines for real engineering applications.