Examination of a high-efficiency solid oxide fuel cell system that reuses exhaust gas

Somekawa, Takaaki; Nakamura, Kazuo; Kushi, Takuto; Kume, T.; Fujita, K.; Yakabe, H.

doi:10.1016/j.applthermaleng.2016.10.096

Cited by 27 publications

(17 citation statements)

References 9 publications

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“…The maximum electrical efficiency theory developed above is applied to fuel cell systems fueled by methane, propane, and hydrogen, assuming both the total pressures of fuel and air are both 1 atm. In most literatures the low heating value (LHV) of a fuel for the fuel cell efficiency was used [3,6,7,13], the numerical results presented here are also based on h fuel (T 0 )=LHV. Conversion to high heating value (HHV) efficiency only requires a scaling factor of LHV/HHV.…”

Section: Numerical Resultsmentioning

confidence: 99%

“…Numerous efforts have been made towards the understanding of the fuel cell electrical efficiency [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. Lutz et al performed a thermodynamic analysis and concluded that the maximum fuel cell efficiency is equivalent to the Carnot cycle with the high temper-ature reservoir set at the fuel combustion temperature [3].…”

Section: Introductionmentioning

confidence: 99%

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Maximum thermodynamic electrical efficiency of fuel cell system and results for hydrogen, methane, and propane fuels

Mao

Xiao

Lin

2018

Chinese Journal of Chemical Physics

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The maximum electrical efficiency of fuel cell system, η max e , is important for the understanding and development of the fuel cell technology. Attempt is made to build a theory for η max e by considering the energy requirement of heating the fuel and air streams to the fuel cell operating temperature T. A general thermodynamic analysis is performed and the energy balances for the overall operating processes of a fuel cell system are established. Explicit expressions for the determination of η max e are deduced. Unlike the Carnot efficiency, η max e is found to be fuel specific. Except for hydrogen fuel, chemical equilibrium calculations are necessary to compute η max e. Analytical solutions for the chemical equilibrium of alkane fuels are presented. The theoretical model is used to analyze the effects of T and the steam contents of CH 4 , C 3 H 8 , and H 2 on η max e for systems with various degrees of waste heat recovery. Contrary to the common perception concerning methane and propane fuels, η max e decreases substantially with the increase of T. Moreover, η max e of hydrogen fuel can be higher than that of methane and propane fuels for a system with a medium level of waste heat recovery and operated at 700 • C≤T ≤900 • C.

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Section: Numerical Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Maximum thermodynamic electrical efficiency of fuel cell system and results for hydrogen, methane, and propane fuels

Mao

Xiao

Lin

2018

Chinese Journal of Chemical Physics

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“…The techniques for removing CO 2 include using a CO 2 absorbent [17,18] or a CO 2 separation membrane [19]. Experimental studies showed that a gross power generation efficiency of DC 77.8% (LHV) was obtained by removing CO 2 as well as H 2 O in the fuel regeneration process using the twostage stacks, although the module had not achieved thermal self-sustainability [15][16]. Raising the stack temperatures also contributes to higher power generation efficiency because the cell voltage increases with the cell temperature during SOFC power generation [20].…”

Section: Resultsmentioning

confidence: 99%

“…Using this technology, the module could be operated at an extremely high total fuel utilization rate without operating individual SOFC stacks at excessively high fuel utilization rates. The authors are not aware of reports on SOFC modules using twostage SOFC stacks and a fuel regeneration process between them, except for the authors' previous studies that experimentally demonstrate the advantages of the technology [15,16]. In the previous study, heaters were used to maintain the stack temperatures.…”

Section: Introductionmentioning

confidence: 99%

Development of a Highly Efficient SOFC Module Using Two‐stage Stacks and a Fuel Regeneration Process

et al. 2017

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A solid oxide fuel cell (SOFC) module using two-stage stacks and a fuel regeneration process between them was developed in this study for the first time, to the best of the authors' knowledge. Upon configuring the first-stage and secondstage stacks and a steam reformer between them in the SOFC module, a gross output power of DC 2.27 kW was generated with gross power generation efficiency of DC 69.2% (lower heating value (LHV)), at a total fuel utilization rate of 86.3%. This technology enables operation at a very high total fuel utilization rate even while operating the stacks at a moderate fuel utilization rate (below 70%). Considering an auxiliary device loss (6%) and inverter loss (5%), the net power generation efficiency is estimated to be AC 61.8% (LHV); hence, the module is considered to exhibit a high power generation efficiency. Further increases in the power generation efficiency could be realized in the future by removing the CO 2 from the anode off-gas during the fuel regeneration process and/or operating the stacks at higher temperatures by decreasing heat leakage from the module.

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“…The basic approach of improving the efficiency of simple once-through SOFC systems is the increase of the global fuel utilization FU while maintaining a suitable local fuel utilization FU at stack level. Two different pathways have been discussed in literature: (i) single-stage SOFC module with anode off-gas recirculation [25][26][27], and (ii) two-stage SOFC module with a fuel regenerator between the modules [13][14][15]28].…”

Section: Sofc Systemsmentioning

confidence: 99%

Modeling of a Novel Atmospheric SOFC/GT Hybrid Process and Comparison with State‐of‐the‐Art SOFC System Concepts

et al. 2020

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A novel concept for an atmospheric solid oxide fuel cell (SOFC) hybrid system applying a sub-atmospheric gas turbine is proposed. Based on a developed process model suitable operating conditions are studied. The resulting performance is compared to different state-of-the-art SOFC system concepts. The comparison shows that pressurized SOFC/GT systems offer the highest electric efficiency. The novel concept as well as a two-stage SOFC system offer lower efficiencies, but still well above 60%. However, avoiding the complex system requirements of pressurized SOFC/GT systems, these concepts are promising for highly efficient electricity generation.

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Examination of a high-efficiency solid oxide fuel cell system that reuses exhaust gas

Cited by 27 publications

References 9 publications

Maximum thermodynamic electrical efficiency of fuel cell system and results for hydrogen, methane, and propane fuels

Maximum thermodynamic electrical efficiency of fuel cell system and results for hydrogen, methane, and propane fuels

Development of a Highly Efficient SOFC Module Using Two‐stage Stacks and a Fuel Regeneration Process

Modeling of a Novel Atmospheric SOFC/GT Hybrid Process and Comparison with State‐of‐the‐Art SOFC System Concepts

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