A simple but effective hybrid ejector model was developed.First a fundamental model for calculating entrainment ratio was derived based on thermodynamic and fluid dynamic principles.Then a 2D velocity function was used to approximate the velocity distribution of entrained flow to simplify the fundamental equation.Based on numerical studies and the lumped-parameter method

the hybrid ejector model was finally established.Compared with the existing models

the developed model was very simple

consisting of only one equation and three constant parameters.Therefore the model can be used in real time control and optimization of ejector systems.Furthermore

the procedure for identifying the parameters was presented.In the end

an ejector refrigeration system with refrigerant R141B was investigated.The results of the experimental validation showed that the proposed model could accurately predict the ejector performance.