Numerical investigation of geometry parameters for pressure recovery of an adjustable ejector in multi-evaporator refrigeration system

In this paper, Computational Fluid Dynamics (CFD) technique is used to investigate the optimum geometry parameters of the adjustable ejector, which is used in variable cooling loads conditions, for the performance of pressure recovery in a multi-evaporator refrigeration system (EMERS) using R134a as the refrigerant. The performance of pressure recovery reflects the performance of the compression energy saving. The developed CFD model is first validated by actual experimental data of an EMERS. The k–ω–sst model is chosen as the turbulence model, and then used to find the optimum geometry parameters: nozzle diverging angle, length of the constant-pressure mixing section, nozzle exit position and converging angle of the constant-pressure mixing section, for high performance in pressure recovery properties. Through the analysis of physical mechanism, the results indicate that the pressure recovery ratio can be efficiently improved after the geometries optimization which is very sensitive to the nozzle diverging angle and the length of the constant-pressure mixing section.