Assessment and prediction of component efficiencies in supersonic ejector with friction losses

In this paper, the influences of friction losses on ejector efficiencies are investigated by the computational fluid dynamics (CFD) technique. Roughness values factor is introduced to analyze ejector performance by considering the components efficiencies. Efficiencies of each component are assessed with different levels of roughness. Validation is given through comparisons between the calculated and experimental values obtained from the ejector refrigerant platform with diverse levels of surface roughness. Results indicate that the efficiency of the ejector decreases with the increase of roughness values and friction losses in constant-area section and diffuser have the most significant impact on ejector performance. By analyzing the relationship between efficiencies and roughness values, an efficiency correlation is built with a coefficient of determination over 0.9654. It is shown that proposed correlations for ejector component efficiencies can be utilized more accurately in system design of ejector based refrigerant system considering the friction losses.