Servizi UNIGE per questo articolo(opens in a new window)|Richiedi articolo via Nilde(opens in a new window)| Export | Download | Add to List | More... Proceedings of the 1st European Fuel Cell Technology and Applications Conference 2005 - Book of Abstracts Volume 2005, 2005, Page 250 1st European Fuel Cell Technology and Applications Conference 2005, EFC2005; Rome; Italy; 14 December 2005 through 16 December 2005; Code 67292 Design and testing of ejectors for hybrid systems (Conference Paper) Ferrari, M.a, Bernardi, D.b, Massardo, A.c a TPG, Università di Genova, Italy b Università di Genova, Italy Abstract The recent developments of hybrid systems based on Solid Oxide Fuel Cell technology have focused the attention on the advantages coming from recirculations carried out by ejectors. In fact, these components join very low costs with high lifetime because they have no moving parts. While on the anodic side an ejector allows to avoid high temperature and expensive blowers to recirculate part of the exhausted gases, on the cathodic side a recirculation based on the ejector technology is so cheap and safe to justify an efficiency decrease. To improve the ejector performance inside the hybrid systems this activity has started at TPG with a preliminary design of an anodic ejector developed using a preliminary 0-D model based on the global balances of mass, momentum and energy. Then, the theoretical activity has been improved with the development of an experimental rig to test single stage ejectors for hybrid systems at different operative conditions of mass flow rates, pressures and temperatures. At first, an open circuit has been built to perform tests at atmospheric conditions in the secondary flow and connecting the primary inlet to the compressed air line. Then, to emulate a SOFC anodic recirculation, the circuit has been closed introducing a fuel cell volume in a reduced scale. This configuration is important to test ejectors at pressurized conditions both at primary and secondary ducts. Finally, the volume has been equipped and thermally insulated to test ejectors with high temperature secondary flow, necessary to reach values in similitude condition with the real ones. This test rig has been used to validate the 0-D ejector model with the objective to set the values of the coefficients used to take into account the primary momentum loss and the mixing chamber viscous pressure losses. On the other hand, a successful comparison with the experimental data, measured with the rig, has been used to validate the CFD models necessary to better investigate the fluid dynamic phenomena inside ejectors. In fact, the application of CFD validated models has allowed to improve the performance of ejectors for hybrid systems optimizing the geometry in terms of primary and secondary ducts, mixing chamber length and diffuser geometry.
Design and testing of ejectors for hybrid systems
FERRARI, MARIO LUIGI;MASSARDO, ARISTIDE
2005-01-01
Abstract
Servizi UNIGE per questo articolo(opens in a new window)|Richiedi articolo via Nilde(opens in a new window)| Export | Download | Add to List | More... Proceedings of the 1st European Fuel Cell Technology and Applications Conference 2005 - Book of Abstracts Volume 2005, 2005, Page 250 1st European Fuel Cell Technology and Applications Conference 2005, EFC2005; Rome; Italy; 14 December 2005 through 16 December 2005; Code 67292 Design and testing of ejectors for hybrid systems (Conference Paper) Ferrari, M.a, Bernardi, D.b, Massardo, A.c a TPG, Università di Genova, Italy b Università di Genova, Italy Abstract The recent developments of hybrid systems based on Solid Oxide Fuel Cell technology have focused the attention on the advantages coming from recirculations carried out by ejectors. In fact, these components join very low costs with high lifetime because they have no moving parts. While on the anodic side an ejector allows to avoid high temperature and expensive blowers to recirculate part of the exhausted gases, on the cathodic side a recirculation based on the ejector technology is so cheap and safe to justify an efficiency decrease. To improve the ejector performance inside the hybrid systems this activity has started at TPG with a preliminary design of an anodic ejector developed using a preliminary 0-D model based on the global balances of mass, momentum and energy. Then, the theoretical activity has been improved with the development of an experimental rig to test single stage ejectors for hybrid systems at different operative conditions of mass flow rates, pressures and temperatures. At first, an open circuit has been built to perform tests at atmospheric conditions in the secondary flow and connecting the primary inlet to the compressed air line. Then, to emulate a SOFC anodic recirculation, the circuit has been closed introducing a fuel cell volume in a reduced scale. This configuration is important to test ejectors at pressurized conditions both at primary and secondary ducts. Finally, the volume has been equipped and thermally insulated to test ejectors with high temperature secondary flow, necessary to reach values in similitude condition with the real ones. This test rig has been used to validate the 0-D ejector model with the objective to set the values of the coefficients used to take into account the primary momentum loss and the mixing chamber viscous pressure losses. On the other hand, a successful comparison with the experimental data, measured with the rig, has been used to validate the CFD models necessary to better investigate the fluid dynamic phenomena inside ejectors. In fact, the application of CFD validated models has allowed to improve the performance of ejectors for hybrid systems optimizing the geometry in terms of primary and secondary ducts, mixing chamber length and diffuser geometry.
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