Experimental characterization of a solid oxide fuel cell coupled to a steam-driven micro anode off-gas recirculation fan

Wagner, Paweł; Wuillemin, Zacharie; Constantin, David; Diethelm, Stefan; herle, Jan Van; Schiffmann, Jürg

doi:10.1016/j.apenergy.2019.114219

Cited by 28 publications

(15 citation statements)

References 19 publications

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“…The power consumption of the digestor and the power consumption of the pump and air fan are considered. The power consumption of the recirculation fan is not considered since the fan is driven by a steam turbine with the steam recovered from the waste heat [13].…”

Section: Plant Efficiency Definitionmentioning

confidence: 99%

Comparison of integrated fuel processing options for biogas-fed solid-oxide fuel cell plants

Loreti

Wang

et al. 2021

E3S Web Conf.

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The Solid-oxide fuel cell is a highly efficient prime mover for biogas conversion, but a part of biogas needs to be reformulated externally to facilitate the electrochemical conversion, easy control of reforming conditions, and thermal management of the stack. Carbon deposition and external mineralcarrying water should be avoided to ensure the durability of the fuel processor and stack catalysts. This paper investigates four plant layouts with different anode off-gas recirculation schemes and biogas reforming methods: (1) pre-reforming with hot recirculation (HR), (2) pre-reforming with cold recirculation (CR), (3) no pre-reforming and hot recirculation (NR), (4) partial oxidation with hot recirculation (PO). All the schemes feature an electrolyte supported SOFC working at 860°C and 0.23 A/cm2 current density. A sensitivity analysis of the plant efficiency as a function of the Recirculation Ratio (RR) and the Reformer Temperature (RT) is performed. The results show that HR and CR schemes achieve the highest efficiency (58-63%). The HR scheme benefits from the recirculated water and does not require external water for RR > 50% and RT > 600°C; the CR scheme achieves the same result for RR > 80% and RT > 700°C. The optimal RR is within 50 – 80% for the highest system efficiency, as a trade-off between the overall fuel utilization and electrochemistry performance. The RT should be between 600 and 700°C. The HR scheme is the overall best performing if the re-circulator and stack designs do not limit the flow rates at a high RR.

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Section: Plant Efficiency Definitionmentioning

confidence: 99%

Comparison of integrated fuel processing options for biogas-fed solid-oxide fuel cell plants

Loreti

Wang

et al. 2021

E3S Web Conf.

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“…The hot air case showed similar predictions: the power 2 varied from −1 W to 8 W and the efficiency 2 varied from 6 % to 16 % points. Water vapor (SOFC): Figure 6 also shows the experimental results of the steam turbine by Wagner et al [14] for an operation in the relevant environment (6 kW e SOFC). The measured water vapor mass flow rate to the hot air mass flow rate corresponds to a value between 0.74 at 115 krpm (inlet temperature of 225 • C) and up to 0.79 at 170 krpm (inlet temperature of 216 • C).…”

Section: Comparison Of the Experimental Results To-wards The Numericamentioning

confidence: 99%

“…According to the authors knowledge, no experimental characterization of a micro steam turbine was published so far, except for the unit presented in this paper. Wagner et al [14] introduced a novel solid oxide fuel cell (SOFC) system with an anode off-gas recirculation fan, that is directly driven by a steam turbine. The steam is provided by the waste heat from the SOFC system.…”

Section: Yearmentioning

confidence: 99%

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Theoretical and Experimental Investigation of a 34 Watt Radial-Inflow Steam Turbine With Partial-Admission

Wagner

herle

Schiffmann

2020

Volume 8: Industrial and Cogeneration; Manufacturing Materials and Metallurgy; Marine; Microturbines, Turbochargers, and Small

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A micro steam turbine with a tip diameter of 15 mm was designed and experimentally characterized. At the nominal mass flow rate and total-to-total pressure ratio of 2.3 kg h−1 and 2, respectively, the turbine yields a power of 34 W and a total-to-static isentropic efficiency of 37%. The steam turbine is conceived as a radial-inflow, low-reaction (15%), and partial admission (21%) machine. Since the steam mass flow rate is limited by the heat provided of the system (solid oxide fuel cell), a low-reaction and high-power-density design is preferred. The partial-admission design allows for reduced losses: The turbine rotor and stator blades are prismatic, have a radial chord length of 1 mm and a height of 0.59 mm. Since the relative rotor blade tip clearance (0.24) is high, the blade tip leakage losses are significant. Considering a fixed steam supply, this design allows to increase the blade height, and thus reducing the losses. The steam turbine drives a fan, which operates at low Mach numbers. The rotor is supported on dynamic steam-lubricated bearings; the nominal rotational speed is 175 krpm. A numerical simulation of the steam turbine is in good agreement with the experimental results. Furthermore, a novel test rig setup, featuring extremely-thin thermocouples (ϕ0.15 mm) is investigated for an operation with ambient and hot air at 220 °C. Conventional zero and one-dimensional pre-design models correlate well to the experimental results, despite the small size of the turbine blades.

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“…State-ofthe-art methane-fueled commercial systems can achieve an electrical efficiency of up to 65% 1 (LHV) at 0.4 A/cm 2 without anode off-gas recirculation, which is one of the current technological trends aiming at increasing the system efficiency. The anode off-gas recirculation can increase the overall fuel utilization [12], reduce or even remove the dependency of fuel reforming on the external water supply [13][14][15][16][17][18]. It can also be applied to the systems with other chemicals.…”

Section: Introductionmentioning

confidence: 99%

Reversible solid-oxide cell stack based power-to-x-to-power systems: Comparison of thermodynamic performance

Wang¹,

Zhang²,

Pérez–Fortes³

et al. 2020

Preprint

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The increasing penetration of variable renewable energies poses new challenges for grid management. The economic feasibility of grid-balancing plants may be limited by low annual operating hours if they work either only for power generation or only for power storage. This issue might be addressed by a dual-function power plant with power-to-x capability, which can produce electricity or store excess renewable electricity into chemicals at different periods. Such a plant can be uniquely enabled by a solid-oxide cell stack, which can switch between fuel cell and electrolysis with the same stack. This paper investigates the optimal conceptual design of this type of plant, represented by power-to-x-to-power process chains with x being hydrogen, syngas, methane, methanol and ammonia, concerning the efficiency (on a lower heating value) and power densities. The results show that an increase in current density leads to an increased oxygen flow rate and a decreased reactant utilization at the stack level for its thermal management, and an increased power density and a decreased efficiency at the system level. The power-generation efficiency is ranked as methane (65.9%), methanol (60.2%), ammonia (58.2%), hydrogen (58.3%), syngas (53.3%) at 0.4 A/cm 2 , due to the benefit of heat-to-chemical-energy conversion by chemical reformulating and the deterioration of electrochemical performance by the dilution of hydrogen. The power-storage efficiency is ranked as syngas (80%), hydrogen (74%), methane (72%), methanol (68%), ammonia (66%) at 0.7 A/cm 2 , mainly due to the benefit of co-electrolysis and the chemical energy loss occurring in the chemical synthesis reactions. The lost chemical energy improves plant-wise heat integration and compensates for its adverse effect on power-storage efficiency. Combining these efficiency numbers of the two modes results in a rank of round-trip efficiency: methane (47.5%) > syngas (43.3%) ≈ hydrogen (42.6%) > methanol (40.7%) > ammonia (38.6%). The pool of plant designs obtained lays the basis for the optimal deployment of this balancing technology for specific applications.

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Experimental characterization of a solid oxide fuel cell coupled to a steam-driven micro anode off-gas recirculation fan

Cited by 28 publications

References 19 publications

Comparison of integrated fuel processing options for biogas-fed solid-oxide fuel cell plants

Comparison of integrated fuel processing options for biogas-fed solid-oxide fuel cell plants

Theoretical and Experimental Investigation of a 34 Watt Radial-Inflow Steam Turbine With Partial-Admission

Reversible solid-oxide cell stack based power-to-x-to-power systems: Comparison of thermodynamic performance

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