Validated ejector model for hybrid system applications

Abstract

The aim of this work is the presentation of a new model for ejector performance calculation using a commercial tool. Due to the critical issues in recirculation performance, special attention is devoted to applications in hybrid systems based on high temperature fuel cells. The theoretical activity is supported by an experimental rig able to operate tests on ejectors at different operative conditions, with a layout similar to the fuel cell anodic recirculation. The model validation, operated considering experimental data obtained with this rig, is essential to evaluate the tool performance for design and off-design calculations. This aspect is particularly critical due to important limitations in the recirculation ratio (especially for the anodic side), to avoid unacceptable operative conditions in the fuel cells.The results presented in this work were obtained with this validated model for an ejector applied on the anodic side of a Solid Oxide Fuel Cell (SOFC). A parametric analysis was carried out to show the effects of several parameters on the recirculation performance. The fully independent analysis of the influence of different properties (carried out with a specifically validated model) is an important innovative result for the application of such ejectors on high temperature fuel cells.

Ejectors on the cutting edge: The past, the present and the perspective

“…This issue is a main drawback as ejector highly influences the system performance, so that ad-hoc operation strategies and design procedures should be applied. In particular, Chen et al [29] studied suitable operation strategies; conversely, Ferrari et al [30] studied the design procedures. Chen et al [29] (anode/cathode ejector recirculation) studied different operation strategies for a hybrid solid oxide fuel cell-gas turbine: to ensure an appropriate operation strategy all the main system parameters should be adjusted to control the anode/cathode temperature difference and turbine inlet temperature.…”

“…Chen et al [29] (anode/cathode ejector recirculation) studied different operation strategies for a hybrid solid oxide fuel cell-gas turbine: to ensure an appropriate operation strategy all the main system parameters should be adjusted to control the anode/cathode temperature difference and turbine inlet temperature. The regulation strategies rely on a precise modeling of ejector performances and, to this end, Ferrari et al [30] (anodic recirculation) presented a CFD model to predict ejector performances in a solid oxide fuel cell; the proposed approach was validated by experimental data and can be used to support the design and control of ejectors in fuel cell systems. It is worth noting that the use of an ejector in proton exchange membrane fuel cell need to consider gas management and water-control strategies.…”

Performance investigation of a multi‐nozzle ejector for proton exchange membrane fuel cell system

“…They concluded that the diameter of the side‐branch secondary flow tube could significantly affect entrainment performance. Ferrari et al 46 employed a 3D CFD model to investigate the ejector performance at both design and off‐design conditions. Mazzelli et al 47 investigated the ejector numerically and experimentally to evaluate turbulence models and 3D effects.…”

Numerical investigation of ejector transient characteristics for a 130‐kW PEMFC system

“…They found that ε‐based models are more accurate at low pressures. Ferrari et al developed an ejector model for the solid oxide fuel cell (SOFC) system. The model is validated by their experimental data.…”

“…They found that ε-based models are more accurate at low pressures. Ferrari et al 23 With the deepening of the research on ejector, some scholars have begun to study the transient process. Clou et al 24 proposed a 1D ejector transient model to investigate the performance in a pulse refrigeration system (PRS).…”