A numerical comparison between ejector performance with convergence and convergence-divergence primary nozzle

In this study, a numerical method is used to investigate the effects convergence primary nozzle on the air ejector performance used in Polymer Electrolyte Membrane Fuel Cell (PEMFC). Simulations have been performed by solving the compressible form of two-dimensional Navier–Stokes equations. The turbulence model have been employed to estimate the turbulent region. A comparison of the computed results with the published experimental data exhibits agreement in terms of entrainment ratio at defined operating conditions. The ejector with convergence nozzle was widely used in the aerospace science, jet engine and Polymer Electrolyte Membrane Fuel Cell, because it has many advantages such as jet noise reduction, prevent condensation of water vapor inside the ejector and improvement of conventional converging-diverging nozzle. According to several applications and advantages of convergence nozzle, effects of primary converging nozzle on the flow characterization and the ejector performance have studied at any part of its. Based on particular application of the ejector with convergence primary nozzle in PEMFC, performance improvement is the purpose of this study. The results have been compared with air ejector with convergence-divergence primary nozzle. The results show that the air ejector performance has been enhanced under changing primary nozzle structure. This means that the ejector can consume available energy in its operation processes optimally beside increasing drawn secondary flow.