Ejector Model for High Temperature Fuel Cell Hybrid Systems: Experimental Validation at Steady-State and Dynamic Conditions

2008 ◽  
Vol 5 (4) ◽  
Author(s):  
Mario L. Ferrari ◽  
Matteo Pascenti ◽  
Aristide F. Massardo
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
High Temperature ◽  
Fuel Cell ◽  
Cell Hybrid ◽  
Experimental Validation ◽  
Test Rig ◽  
Transient Conditions ◽  
Recirculation Model ◽  
Fuel Cell Hybrid

The aim of this work is the experimental validation of a steady-state and transient ejector model for high temperature fuel cell hybrid system applications. This is a mandatory step in performing the steady state and the transient analysis of the whole plant to avoid critical situations and to develop the control system. The anodic recirculation test rig, developed at TPG-University of Genoa, and already used in previous works to validate the ejector design models (0D and computational fluid dynamics), was modified and used to perform tests at transient conditions with the aim of ejector transient model validation. This ejector model, based on a “lumped volume” technique, has been successfully validated against experimental data at steady-state and transient conditions using air or CO2 at room temperature and at 150°C in the secondary duct inlet. Then, the ejector model was integrated with the models of the connecting pipes, and with the volume simulation tool, equipped with an outlet valve, in order to generate an anodic recirculation model. Also in this case, the theoretical results were successfully compared with the experimental data obtained with the test rig. The final part of the paper is devoted to the results obtained with square wave functions generated in the ejector primary pressure. To study the effects of possible fast pressure variations in the fuel line (ejector primary line), the test rig was equipped with a servo-controlled valve upstream of the ejector primary duct to generate different frequency pressure oscillations. The results calculated with the recirculation model at these conditions were successfully compared with the experimental data too.

Physical Simulator of Start-Up for Hybrid System Cathode Side

2006 ◽  
Author(s):  
A. Traverso ◽  
M. L. Ferrari ◽  
M. Pascenti ◽  
A. F. Massardo
Keyword(s):  
High Temperature ◽  
Fuel Cell ◽  
Hybrid Systems ◽  
Hybrid System ◽  
Cell Hybrid ◽  
Cathode Side ◽  
Outlet Temperature ◽  
Test Rig ◽  
Start Up ◽  
Fuel Cell Hybrid

A start-up test rig at TPG laboratory at the University of Genoa, Italy, has been designed and built for two main purposes: physically simulating different early start-up layout and procedures of high temperature fuel cell hybrid systems, and validating time-dependent hybrid system models based on TRANSEO software. Since start-up is a critical operating phase for high temperature fuel cell hybrid systems, and it may require specific modifications to the hybrid system layout, the start-up test rig is meant to be very flexible for testing several start-up layouts as well as the coupling of different turbomachines and stacks. Results for cold test, 700°C and 950°C start-up combustor outlet temperature tests are reported. Such results show the pressure and temperature quick rise during the early phase of start-up, which could represent an issue for the mechanical and thermal stress to the stack. A dynamic model of the test rig was built up and validated showing good agreement with the experimental results. This achievement was very useful to increase the confidence with predictive dynamic simulation tools during the start-up phase, where experimental data are hardly available and where the fuel cell materials may undergo risky thermal shocks.

Hybrid System Test Rig: Start-up and Shutdown Physical Emulation

2010 ◽  
Vol 7 (2) ◽  
Author(s):  
Mario L. Ferrari ◽  
Matteo Pascenti ◽  
Loredana Magistri ◽  
Aristide F. Massardo
Keyword(s):  
Control System ◽  
Thermal Stress ◽  
High Temperature ◽  
Fuel Cell ◽  
Hybrid System ◽  
Cell Hybrid ◽  
Test Rig ◽  
Start Up ◽  
Outlet Flow ◽  
Integrated Project

The University of Genoa (TPG) has designed and developed an innovative test rig for high temperature fuel cell hybrid system physical emulation. It is based on the coupling of a modified commercial 100 kW recuperated micro gas turbine to a special modular volume designed for the experimental analysis of the interaction between different dimension fuel cell stacks and turbomachines. This new experimental approach that generates reliable results as a complete test rig also allows investigation of high risk situations with more flexibility without serious and expensive consequences to the equipment and at a very low cost compared with real hybrid configurations. The rig, developed with the support of the European Integrated Project “FELICITAS,” is under exploitation and improvement in the framework of the new European Integrated Project “LARGE-SOFC” started in January 2007. The layout of the system (connecting pipes, valves, and instrumentation) was carefully designed to minimize the pressure loss between compressor outlet and turbine inlet to have the highest plant flexibility. Furthermore, the servocontrolled valves are useful for performing tests at different operative conditions (i.e., pressures, temperatures, and pressure losses), focusing the attention on surge and thermal stress prevention. This work shows the preliminary data obtained with the machine connected to the volume for the test rig safe management to avoid surge or excessive stress, especially during the critical operative phases (i.e., start-up and shutdown). Finally, the attention is focused on the valve control system developed to emulate the start-up and shutdown phases for high temperature fuel cell hybrid systems. It is necessary to manage the flows in the connecting pipes, including an apt recuperator bypass, to perform a gradual heating up and cooling down as requested during these phases. It is an essential requirement to avoid thermal stress for the fuel cell stack. For this reason, during the start-up, the volume is gradually heated by the compressor outlet flow followed by a well managed recuperator outlet flow and vice versa for the shutdown. Furthermore, operating with a constant rotational speed control system, the machine load is used to reach higher temperature values typical of these kinds of systems.

Thermoeconomic analysis of a fuel cell hybrid power system from the fuel cell experimental data

Energy ◽  
2006 ◽  
Vol 31 (10-11) ◽  
pp. 1358-1370 ◽  
Author(s):  
Tomás Álvarez ◽  
Antonio Valero ◽  
José M. Montes
Keyword(s):  
Experimental Data ◽  
Fuel Cell ◽  
Power System ◽  
Cell Hybrid ◽  
Hybrid Power System ◽  
Hybrid Power ◽  
Fuel Cell Hybrid

Experimental Validation of an Unsteady Ejector Model for Hybrid Systems

2006 ◽  
Author(s):  
Mario L. Ferrari ◽  
Matteo Pascenti ◽  
Aristide F. Massardo
Keyword(s):  
Experimental Data ◽  
Steady State ◽  
Transient Analysis ◽  
Experimental Validation ◽  
Second Step ◽  
Test Rig ◽  
Transient Model ◽  
Initial Validation ◽  
Cfd Models ◽  
Whole Plant

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.

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