Model of a novel pressurized solid oxide fuel cell gas turbine hybrid engine

Burbank, Winston S.; Witmer, Dennis; Holcomb, Franklin H.

doi:10.1016/j.jpowsour.2009.04.004

Cited by 60 publications

(30 citation statements)

References 19 publications

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“…Akkaya et al [14] introduced an exergetic performance coefficient to quantify the second law thermodynamic performance of the hybrid plant, and allowed for easy identification of the chief sources of exergy destruction in the plant. Burbank et al [15] considered a pressurized SOFC-GT engine which entailed a variable geometry nozzle turbine to directly influence the airflow as well as an auxiliary combustor to control the temperature of turbomachinery. They found that this plant could operate over a 5:1 turndown ratio.…”

Section: Open Accessmentioning

confidence: 99%

Integration of A Solid Oxide Fuel Cell into A 10 MW Gas Turbine Power Plant

Cheddie

2010

Energies

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Power generation using gas turbine power plants operating on the Brayton cycle suffers from low efficiencies. In this work, a solid oxide fuel cell (SOFC) is proposed for integration into a 10 MW gas turbine power plant, operating at 30% efficiency. The SOFC system utilizes four heat exchangers for heat recovery from both the turbine outlet and the fuel cell outlet to ensure a sufficiently high SOFC temperature. The power output of the hybrid plant is 37 MW at 66.2% efficiency. A thermo-economic model predicts a payback period of less than four years, based on future projected SOFC cost estimates.

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Section: Open Accessmentioning

confidence: 99%

Integration of A Solid Oxide Fuel Cell into A 10 MW Gas Turbine Power Plant

Cheddie

2010

Energies

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“…A similar analysis of tubular SOFC-GT hybrids utilized a dual mode generator/ motor in conjunction with a battery to improve transient load following in a small, 5 kW, transportation application which lacked any air flow control due to the small size [28]. Steady-state analyses offer insights into off-design performance with high turndown ratios, up to 5:1 [29], without considering the transient response and necessary control requirements. Proposed strategies for controlling stack air flow include variable speed turbines [30,31], variable inlet nozzle geometry [29], variable inlet guide vanes, variable flow ejectors [32], and bypass valves.…”

Section: Introductionmentioning

confidence: 99%

“…Steady-state analyses offer insights into off-design performance with high turndown ratios, up to 5:1 [29], without considering the transient response and necessary control requirements. Proposed strategies for controlling stack air flow include variable speed turbines [30,31], variable inlet nozzle geometry [29], variable inlet guide vanes, variable flow ejectors [32], and bypass valves. SOFC-GT hybrids have been shown to exhibit high efficiency with turndown ratios of 5:1 [29].…”

Section: Introductionmentioning

confidence: 99%

“…Proposed strategies for controlling stack air flow include variable speed turbines [30,31], variable inlet nozzle geometry [29], variable inlet guide vanes, variable flow ejectors [32], and bypass valves. SOFC-GT hybrids have been shown to exhibit high efficiency with turndown ratios of 5:1 [29]. Highly dynamic applications require manipulation of the cathode air flow rate through recirculation, bypass or variable mass flow turbomachinery [30e32].…”

Section: Introductionmentioning

confidence: 99%

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Fuel cell–gas turbine hybrid system design part II: Dynamics and control

McLarty

Brouwer

Samuelsen

2014

Journal of Power Sources

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h i g h l i g h t sDynamics and controls development for fuel cell gas turbine (FC-GT) hybrid systems. Molten carbonate hybrid achieves 2:1 turndown at 66% efficiency (LHV) and 1.5 MW. Solid oxide hybrid achieves 4:1 turndown at 71% % efficiency (LHV) and 100 MW. Spatial temperature variation and surge margin are maintained during transients. Cascaded PeI controllers with feed-forward are utilized for hybrid system control. a r t i c l e i n f o a b s t r a c tFuel cell gas turbine hybrid systems have achieved ultra-high efficiency and ultra-low emissions at small scales, but have yet to demonstrate effective dynamic responsiveness or base-load cost savings. Fuel cell systems and hybrid prototypes have not utilized controls to address thermal cycling during load following operation, and have thus been relegated to the less valuable base-load and peak shaving power market. Additionally, pressurized hybrid topping cycles have exhibited increased stall/surge characteristics particularly during off-design operation. This paper evaluates additional control actuators with simple control methods capable of mitigating spatial temperature variation and stall/surge risk during load following operation of hybrid fuel cell systems. The novel use of detailed, spatially resolved, physical fuel cell and turbine models in an integrated system simulation enables the development and evaluation of these additional control methods. It is shown that the hybrid system can achieve greater dynamic response over a larger operating envelope than either individual sub-system; the fuel cell or gas turbine. Results indicate that a combined feed-forward, PeI and cascade control strategy is capable of handling moderate perturbations and achieving a 2:1 (MCFC) or 4:1 (SOFC) turndown ratio while retaining >65% fuel-to-electricity efficiency, while maintaining an acceptable stack temperature profile and stall/surge margin.

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“…The high operating temperatures, combined with the ceramic fuel cell ability to operate at elevated pressure, raise the possibility for thermal integration with additional devices and end-uses. Combined heat and power applications [11][12][13] or integration with a gas turbine generator [14][15][16][17] are two promising SOFC system design options. In the SOFC/GT hybrid system, the fuel cell high temperature SOFC exhaust drives a gas turbine, providing air flow and pressurizing the SOFC while driving an electric generator that produces additional electrical power.…”

Section: Introductionmentioning

confidence: 99%

Experimental and theoretical evidence for control requirements in solid oxide fuel cell gas turbine hybrid systems

McLarty

Kuniba

Brouwer

et al. 2012

Journal of Power Sources

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a b s t r a c tHybrid fuel cell gas turbine sensitivity to ambient perturbations is analyzed using experimental and dynamic simulation results. Experimental data gathered from the world's first pressurized hybrid SOFC-GT system tested at the University of California, Irvine, capture performance variations due to diurnal temperature oscillations. A dynamic modeling methodology demonstrates accuracy, robustness, and clearly identifies critical system sensitivities that require additional control systems development. Simulation results compare favorably with dynamic experimental responses. Predictions of component temperatures, pressures, voltage and system power exhibited 5• C, 2 kPa, 2 mV, and 0.5% error respectively. Moderate ambient temperature fluctuations, 15• C, caused variations in stack temperature of 30 • C, and system power of 5 kW. Small to moderate changes in fuel composition produced 30• C shifts in stack temperature and 25% changes in system power. Simple control loops manipulating fuel cell air flow through SOFC bypass and inlet temperature through recuperator bypass are shown to effectively mitigate internal temperature transients at the expense of reduced system output. The observed temperature fluctuations resulting from typical environmental perturbations are of concern for performance loss and diminished longevity. Experiments and dynamic simulation results indicate the importance of integrated control systems development for hybrid fuel cell gas turbine systems.

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Model of a novel pressurized solid oxide fuel cell gas turbine hybrid engine

Cited by 60 publications

References 19 publications

Integration of A Solid Oxide Fuel Cell into A 10 MW Gas Turbine Power Plant

Integration of A Solid Oxide Fuel Cell into A 10 MW Gas Turbine Power Plant

Fuel cell–gas turbine hybrid system design part II: Dynamics and control

Experimental and theoretical evidence for control requirements in solid oxide fuel cell gas turbine hybrid systems

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