Experimental Validation of an Unsteady Ejector Model for Hybrid Systems

Abstract

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.\ud 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

Physical Simulator of Start-Up for Hybrid System Cathode Side

“…Figure 11 reports the mass flow behaviors as well as the non-dimensional pressure rise across the ejector. The calculated mass flow rates match the experimental data with good accuracy and the errors in the initial part of the ejector differential pressure is in agreement with the model performance at low mass flow rate values presented in previous works [10]. Comparing the mass flow at compressor outlet and the mass flow through the ejector primary nozzle, it is evident that about half the compressed air, a part from storage phenomena, passes through the start-up combustor line (which is off in this test): this is similar also in the other tests and it is mainly due to the relatively high pressure drop through the ejector primary nozzle.…”

“…The models of the components (heat exchangers, volumes, thermal capacitances and pipes) have been validated through experimental measurements: one of the latest achievements is reported in [10].…”

Early start-up of solid oxide fuel cell hybrid systems with ejector cathodic recirculation: Experimental results and model verification

“…9 Rotational speed of both shafts referred to the design conditions [2,7] Fig. 10 Ambient temperature test: mass flow rates and ejector pressure rise results in previous works [14]. As a general comment, the good consistency was achieved mainly thanks to the complete knowledge about the test rig dimensions, volumes, masses, and operating procedure, unlike industrial plants, where details about equipment are often missing.…”

“…It is a validated visual, user-friendly, modular program, organized in an easy-access library, implemented for the off-design, transient, and dynamic analyses of advanced energy systems based on microturbine technology [5]. The models of the components (ejector [13], volumes, thermal capacitances, and pipes) have been validated through experimental measurements: one of the latest achievements is reported in references [11] and [14].…”