Transient characteristics investigation of the integrated ejector-driven hydrogen recirculation by multi-component CFD simulation

The hydrogen supply of the fuel cell system is realized by the cooperation of multiple components. Transient characteristics of a single component can affect the performance of other components. In this study, a three-dimensional multi-component computational fluid dynamics (CFD) model was developed to investigate the synergistic transient characteristics of the hydrogen recirculation components such as hydrogen injector, ejector, and purge valve in an 80 kW PEMFC. The results show that the entrainment performance of the ejector is reduced under unsteady purge conditions compared with steady conditions. The pressure fluctuation of the secondary flow is significant even under purge closed durations. There are drastic changes in velocity and pressure in the ejector, especially in the mixing chamber. Moreover, an abundant hydrogen supply capacity of the injector is necessary to deal with the excessive anode pressure fluctuation. The feedforward-feedback integrated control of the injector is a more efficient strategy to reduce pressure fluctuations compared with the feedback control.