The influence of the area ratio on ejector efficiencies in the MED-TVC desalination system

In this paper, an axi-symmetric computational fluid dynamics (CFD) model is used to investigate the effect of the area ratio on ejector component efficiencies. The geometrical parameters and operating conditions are designed for thermal vapor compression (TVC) used in multi-effect distillation (MED) desalination system. By changing the primary nozzle throat diameter and ejector throat diameter, two groups of ejectors are tested under different operating conditions. The results show that the mixing efficiency plays a more important role in ejector performance than other efficiencies such as primary nozzle efficiency, suction efficiency and diffuser efficiency with the changing of the area ratio. The mixing efficiency can be improved as much as 200% by adjusting the area ratio, and the entrainment ratio is increased from 0.025 to 0.8. Finally empirical correlations are summarized to estimate ejector component efficiencies.