Performance evaluation and parametric studies on variable nozzle ejector using R134A

Abstract

Computational fluid dynamics of variable nozzle ejector has been studied to determine the optimum nozzle exit position for reliable ejector cooling cycle operations. The flow rates of primary and secondary stream were varied to obtain the optimum entrainment ratio under different ranges of operating conditions.The refrigerant R134a was chosen based on the merit of its environmental and performance characteristics, the refrigerant was chosen because currently is used widely in air conditioning system. It was found that the computational fluid dynamics showed that the optimum positioning of nozzle exit position, which was based on the parameters such as pressure inlet variation the temperature inlet. The results obtained after the optimization of the results showed that the optimum nozzle exit position was found at 3 mm from the mixing chamber inlet when the operating conditions pressure inlet, secondary pressure inlet, primary temperature inlet and outlet pressure were at (18bar,6bar,373K,and5.6bar) respectively. Similarly, the range of entrainment ratio was varied between 0.24−1.283 at a constant area ratio, and at varied operating conditions. Keywords: Ejector, Variable nozzle, Cooling system, Entrainment ratio, Turbulence models