Numerical modeling and analysis of ejector in the proton exchange membrane fuel cell system

Computational fluid dynamics (CFD) technique is employed to study the performance of ejector in the fuel delivery line of polymer electrolyte membrane (PEM) fuel cell system. Four different ejector geometries are established and tested under 34 different working conditions. It is found that the humidity at the ejector exit increases with the pressure ratio alpha_P at first then decreases with it. The humidity always decreases with increasing the diameter ratio alpha_D. Results show that there is an inverse relationship between the humidity and the entrainment ratio of the ejector.