Design of an Ejector for a Hydrogen Recirculation System for a PEM Fuel Cell

One of the issues that need to be addressed in order to improve the durability and efficiency of a PEM fuel cell system is the management of the hydrogen feeding procedure. It has been demonstrated these aspects are improved when a hydrogen recirculation systems are used [1]. In this work, an ejector has been designed and manufactured and implemented in an experimental PEM fuel cell Test Station to analyze how ejector based hydrogen recirculation systems affect PEM fuel cells. The proper design of an ejector must take into account several geometrical parameters that can only be studied using Computational Fluid Dynamics (CFD). Thus, a CFD model has been implemented with an axisymmetric geometry and the standard k-ε model to approximate the Favre-averaged Navier-Stokes equations. An experimental ejector has been used to validate the CFD model, obtaining very good agreement between experimental results and the model. Finally, a parametric study has been done to find the optimum geometrical parameters for the ejector to be implemented in the Test Station.