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Thermal Analysis of Steam Ejector Using CFD

T.Aravind , Dr P Ravinder Reddy , S S Baserkoed

This work focuses on the numerical simulation of the working of a steam ejector in order improve the performance. Computational Fluid Dynamics (CFD) was employed for the numerical simulation. In this work the effect of operating conditions on the performance of the steam ejector operating in conjunction with an ejector refrigeration cycle was considered along with the effect of geometry parameter. The model and meshing is done with GAMBIT and FLUENT solver is used for the analysis. The simulations are performed with different operating conditions and geometries. The entrainment ratio is found to increase with the decrease of boiler saturation temperature for the same condition of superheat, evaporator temperature and condenser pressure. The entrainment ratio is also found to increase with increase of evaporator temperature keeping the boiler temperature and condenser pressure constant. The entrainment ratio does not vary much with the condenser pressure until the critical condenser pressure. It is also found that the entrainment ratio increases with decrease of throat diameter of the primary nozzle. The increase of entrainment ratio can be found out from the moving downwards of the effective position. But, a larger mass of secondary fluid causes the momentum of the mixed stream to decrease. The decrease of momentum can be determined from the moving upstream of the shocking position. The movement of shocking position upstream can cause the ejector to operate at a lower critical condenser pressure.