Time Characterization of the Anodic Loop of a Pressurized Solid Oxide Fuel Cell System

Traverso, Alberto; Trasino, Francesco; Magistri, Loredana; Massardo, Aristide F.

doi:10.1115/1.2772638

Cited by 14 publications

(5 citation statements)

References 10 publications

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“…All the SOFC hybrid system components are modelled with the "lumped volume" technique that was explained, for the ejector, in [28,29]. Hence, they consist of an off-design model and a constant area pipe for the fluid dynamic delay.…”

Section: The Plant Modelmentioning

confidence: 99%

“…The compressor and turbine models, based on the characteristic non-dimensional curves, the quasi 2-D recuperator model and the average SOFC temperature model, based on the tubular geometry shown in [30], were presented and validated in previous studies where a detailed description can be found [25][26][27][28][29]. For instance, in [31,32] TRANSEO approach to microturbine-based systems was completely validated against experimental data; the ejector model experimental verification was carried out in [33] and the simplified fuel cell approach was successfully tested in [34].…”

Section: The Plant Modelmentioning

confidence: 99%

“…11) is always within an acceptable range (STCR ≥1.8 [24]) and the differential pressure between the anodic and the cathodic sides (Fig. 14) is never too high (30 mbar is considered acceptable [29]; however, usually this differential pressure limit value depends on SOFC technology and is not available for confidentiality reasons). It is important to emphasize that, because of the reforming reaction behaviour, the fuel cell anodic inlet STCR is lower and, therefore, more critical than that inside the reformer.…”

Section: Reports a Rapid Rotationalmentioning

confidence: 99%

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Solid oxide fuel cell hybrid system: Control strategy for stand-alone configurations

Ferrari¹

2011

Journal of Power Sources

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Section: The Plant Modelmentioning

confidence: 99%

Section: The Plant Modelmentioning

confidence: 99%

Section: Reports a Rapid Rotationalmentioning

confidence: 99%

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Solid oxide fuel cell hybrid system: Control strategy for stand-alone configurations

Ferrari¹

2011

Journal of Power Sources

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“…They reported the interaction between micro gas turbine (MGT) and AGR and the effects of cathode-anode differential pressure on design at rated load operation. In addition, the performance of an SOFC/MGT hybrid system on off-design operation, i.e., start-up and shutdown (Ferrari et al [5]) and load changes (Traverso et al [6], Ferrari [7]) were reported. Zhu et al [8] used a 2D ejector model to analyze the performance of an ejector consisting of a con verging-diverging nozzle in an SOFC system with AGR.…”

Section: Developm Ent Of Anode Gas Recycle System Using Ejector For 1mentioning

confidence: 97%

Development of Anode Gas Recycle System Using Ejector for 1 kW Solid Oxide Fuel Cell

Baba

Kobayashi

Takahashi

et al. 2014

Journal of Engineering for Gas Turbines and Power

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An anode gas recycle (AGR) system using an ejector fo r 1 kW solid oxide fuel cells (SOFCs) was developed to increase the electrical efficiency o f combined power genera tion. We call this an AGR-SOFC. The effects o f recirculation ratio, externally steam feed rate, and fuel utilization were determined experimentally on the AGR-SOFC perform ance (i.e., output power, stack temperature, and gas composition) using a variable flow ejector and a recirculation ratio o f 0. 55-0.62, overall fuel utilization o f 0.720-84, and steam feed rate o f 0-1.5 glmin. A quadrupole mass spectrometer was used to identify the recirculation ratio, the gas composition o f reformed gas at the AGR-SOFC inlet, and that o f the recycle gas at the outlet. Compared to one-path SOFC systems, i.e., without an AGR, the AGR-SOFC was stable and generated about 15 W more electricity when the overall fuel utilization was 0.84 and the recirculation ratio was 0.622 with no steam sup ply. This improved performance was due to the reduced H20 concentration in the anodic gas. In addition, although the recirculation ratio did not affect the AGR-SOFC perform ance, a high recirculation ratio can provide steam produced via the electrochemical reaction to the injected fuel fo r the steam reforming process.In tro d u ctio n SOFCs applied to stationary power generation systems have two major advantages: (i) Highest efficiency among all fuel cells, (ii) lower cost by using nonplatinum catalysts. Furthermore, micro combined heat and power (mCHP) systems based on SOFCs are being actively researched to obtain an even higher efficiency by utilizing the high temperature exhaust gas (>700 °C) from the SOFC itself. Unlike gas turbine engines, Stirling engines are external combustion engines that can be combined with SOFCs at normal pressures with practical efficiencies of roughly 20% for small scale power generation about 1 kW class. In addition, oper ating temperature of a Stirling engine is near the exhaust tempera ture of an SOFC. Takahashi et al.[1] investigated the performance of a combined SOFC-Stirling engine system fueled with methane by means of thermodynamic system modeling. The results showed a 10% higher efficiency for the combined system at low excess air ratio (<2.0), compared with SOFC systems alone. They also stated the need to develop a steam reforming sys tem with an anode gas recirculation to improve the electrical effi ciency of combined power generation.Steam is required to convert hydrocarbon fuel to hydrogen and carbon monoxide. This method is called steam reforming process.Hydrogen and carbon monoxide are produced from methane under high temperature conditions via steam reforming reaction and water-gas shift reaction to prevent carbon deposition on the anode. Assuming that the inflow rate of the steam is 2.5 times higher than that of the fed methane fuel, 175kJ/mol of methane must be provided to convert water at 25 °C to steam at 800 °C. In other words, about 20% of the enthalpy of the methane combus tion (890kJ/mol) is consumed in the produc...

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“…Transfer functions of several parameters were developed to evaluate the dynamics of the integrated system, and could be used to implement a reliable control strategy. Time-scale characterization [31,32] and transfer functions development [25,27,33] are fundamental steps for control system design.…”

Section: Introductionmentioning

confidence: 99%

Transfer function development for SOFC/GT hybrid systems control using cold air bypass

Zaccaria

Tucker

Traverso³

2016

Applied Energy

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Fuel cell gas turbine hybrids present significant challenges in terms of system control because of the coupling of different timescale phenomena. Hence, the importance of studying the integrated system dynamics is critical. With the aim of safe operability and efficiency optimization, the cold air bypass valve was considered an important actuator since it affects several key parameters and can be very effective in controlling compressor surge. Two different tests were conducted using a cyber-physical approach. The Hybrid Performance (HyPer) facility couples gas turbine equipment with a cyber physical solid oxide fuel cell in which the hardware is driven by a numerical fuel cell model operating in real time. The tests were performed moving the cold air valve from the nominal position of 40% with a step of 15% up and down, while the system was in open loop, i.e. no control on turbine speed or inlet temperature. The effect of the valve change on the system was analyzed and transfer functions were developed for several important variables such as cathode mass flow, total pressure drop and surge margin. Transfer functions can show the response time of different system variables, and are used to characterize the dynamic response of the integrated system. Opening the valve resulted in an immediate positive impact on pressure drop and surge margin. A valve change also significantly affected fuel cell temperature, demonstrating that the cold air bypass can be used for thermal management of the cell.

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Time Characterization of the Anodic Loop of a Pressurized Solid Oxide Fuel Cell System

Cited by 14 publications

References 10 publications

Solid oxide fuel cell hybrid system: Control strategy for stand-alone configurations

Solid oxide fuel cell hybrid system: Control strategy for stand-alone configurations

Development of Anode Gas Recycle System Using Ejector for 1 kW Solid Oxide Fuel Cell

Transfer function development for SOFC/GT hybrid systems control using cold air bypass

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