Design and performance test of subsonic ejector for proton exchange membrane fuel cell based on thermodynamic model

A new thermodynamic mathematical model of subsonic ejector for proton exchange membrane fuel cell was deduced according to gas thermodynamic equation, fluid continuity, momentum conservation and kinetic conservation. Two instances, the entrained hydrogen with and without being humidified, were designed and the initial parameters based on the actual operation condition of PEMFC system were provided. The throat diameter and the mixing tube diameter were finally calculated by the ejector thermodynamic mathematical model. An ejector was manufactured for a 3.5 kW rated power PEMFC system based on the calculated result. Its entrainment ratio was tested through both the ejector performance test facility and the thermodynamic mathematical model, and the entrainment performance of the designed ejector was good. At the same time, the hydrogen mole recirculation ratio was advanced, which can represent the hydrogen fuel stoichiometric ratio in the PEMFC stack.