Experimental Validation of an Unsteady Ejector Model for Hybrid Systems

The aim of this work is the experimental validation of a transient ejector model for hybrid system applications. This is a mandatory step in performing the transient analysis of the whole plant to avoid critical situations and to develop the control system. So, the anodic recirculation test rig already used in previous works to study the ejector design validating the steady-state 0-D and CFD models, was used in this work to perform tests at transient conditions and to validate the ejector transient model. An initial validation was carried out at steady-state conditions, then the ejector transient model was successfully compared with the experimental data, also under unsteady conditions. A second step was carried out to better investigate the whole anodic recirculation system. So, the validated ejector transient model was connected to the components necessary to simulate the pipes, the valves and the anodic volume. Also in this case, the calculated results were successfully compared with the experimental data obtained with the laboratory test rig. The final part of the paper is devoted to the results obtained at impulse conditions. In fact, this work investigates the effects on the anodic ejector and on the whole anodic circuit coming from fuel line impulses caused by possible unsteadiness conditions. The results obtained with impulses at different frequency values were successfully compared with the experimental data.