Stack of solid oxide fuel cells

2014 ◽  
Vol 31 (3) ◽  
pp. 207-211 ◽  
Author(s):  
Barbara Dziurdzia ◽  
Zbigniew Magonski ◽  
Henryk Jankowski
Keyword(s):  
Fuel Cell ◽  
Cell Structure ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Content Type ◽  
Fuel Distribution ◽  
Temperature Changes ◽  
Rapid Temperature ◽  
Ceramic Fuel ◽  
Full Power

Purpose – The paper aims to present the innovative design of a planar multilayered high temperature solid oxide fuel cell (SOFC), which is easy to manufacture, and features high resistance to rapid temperature changes. Temperature resistance was accomplished thanks to easy to heat, thin flat ceramic structure of the cell and elimination of metallic interconnections. Design/methodology/approach – The ceramic fuel cell consists of the anode core made of six to eight layers of nickel/yttria-stabilized zirconia tapes (Ni/YSZ) isostatically pressed into a laminate. Two networks of fuel distribution microchannels are engraved on both sides of the anode laminate. The microchannels are subsequently covered with a thin layer of the functional anode tape made of Ni/YSZ and a solid electrolyte tape made of YSZ. Findings – The single planar double-sided ceramic SOFC of dimensions 19 × 60 × 1.2 mm3 provides 3.2 Watts of electric power. The prototype of the battery which consists of four SOFCs provides an output power of > 12 W. Tests show that the stack is resistant to the rapid temperature change. If inserted into a chamber preheated to 800°C, the stack provides the full power within 5 minutes. Multiple cycling does not destroy the stack. Originality/value – This anode-supported fuel cell structure is provided with thin anode functional layers suspended on a large number of fine beams. The whole anode structure is made with the same ceramic material, so the mechanical stress is minimized during the cell operation.

Development of Fabrication Processes for Tubular Solid Oxide Fuel Cell (SOFC) by Plasma Spraying

1998 ◽  
Author(s):  
W.T. Ju ◽  
S.H. Hong
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Plasma Spray ◽  
Cell Structure ◽  
Atmospheric Pressure Plasma ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Air Electrode ◽  
Ceramic Electrolyte ◽  
Ysz Electrolyte

Abstract The atmospheric pressure plasma spray processes for functional layers of the tubular solid oxide fuel cell are developed to build a fuel cell structure consisting of air electrode, ceramic electrolyte, and fuel electrode. Further more the characteristics of each film are also investigated. The layers of LSM (La0.65Sr0.35MnO3) air electrode and Ni/8YSZ fuel electrode have porosities of 23 ~32 % sufficient for supplying fuel and oxidant gases efficiently to electrochemical reaction interfaces. The measured electrical conductivities of the electrodes are higher than 90 S/cm at 1000 °C, which satisfy the requirement as the current collecting electrodes. The YSZ electrolyte film has a high ionic conductivity of 0.07 S/cm at 1000 °C, but shows a bit too porous to block the oxygen molecule penetration through it. A unit tubular SOFC is fabricated by the optimized plasma spray processes for depositing each functional film and forming a porous cylindrical supporting tube of the cell, and turns out to have a promising capability of electricity generation.

Entropy generation analysis for the design optimization of solid oxide fuel cells

2011 ◽  
Vol 21 (5) ◽  
pp. 535-558 ◽  
Author(s):  
Adriano Sciacovelli ◽  
Vittorio Verda
Keyword(s):  
Fuel Cell ◽  
Power Density ◽  
Entropy Generation ◽  
Solid Oxide ◽  
Optimization Process ◽  
Methane Steam Reforming ◽  
Geometrical Parameters ◽  
Oxide Fuel ◽  
Content Type ◽  
Independent Variables

PurposeThe aim of this paper is to investigate performance improvements of a monolithic solid oxide fuel cell geometry through an entropy generation analysis.Design/methodology/approachThe analysis of entropy generation rates makes it possible to identify the phenomena that cause the main irreversibilities in the fuel cell, to understand their causes and to propose changes in the design and operation of the system. The various contributions to entropy generation are analyzed separately in order to identify which geometrical parameters should be considered as the independent variables in the optimization procedure. The local entropy generation rates are obtained through 3D numerical calculations, which account for the heat, mass, momentum, species and current transport. The system is then optimized in order to minimize the overall entropy generation and increase efficiency.FindingsIn the optimized geometry, the power density is increased by about 10 per cent compared to typical designs. In addition, a 20 per cent reduction in the fuel cell volume can be achieved with less than a 1 per cent reduction in the power density with respect to the optimal design.Research limitations/implicationsThe physical model is based on a simple composition of the reactants, which also implies that no chemical reactions (water gas shift, methane steam reforming, etc.) take place in the fuel cell. Nevertheless, the entire procedure could be applied in the case of different gas compositions.Practical implicationsEntropy generation analysis allows one to identify the geometrical parameters that are expected to play important roles in the optimization process and thus to reduce the free independent variables that have to be considered. This information may also be used for design improvement purposes.Originality/valueIn this paper, entropy generation analysis is used for a multi‐physics problem that involves various irreversible terms, with the double use of this physical quantity: as a guide to select the most relevant design geometrical quantities to be modified and as objective function to be minimized in the optimization process.

Reliability analysis for a multi-stack solid oxide fuel cell system subject to operation condition-dependent degradation

2020 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Konrad W. Eichhorn Colombo ◽  
Peter Schütz ◽  
Vladislav V. Kharton
Keyword(s):  
Experimental Data ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Reliability Analysis ◽  
Dynamic Program ◽  
Solid Oxide ◽  
System Level ◽  
Oxide Fuel ◽  
Content Type ◽  
Start Up

PurposeA reliability analysis of a solid oxide fuel cell (SOFC) system is presented for applications with strict constant power supply requirements, such as data centers. The purpose is to demonstrate the effect when moving from a module-level to a system-level in terms of reliability, also considering effects during start-up and degradation.Design/methodology/approachIn-house experimental data on a system-level are used to capture the behavior during start-up and normal operation, including drifts of the operation point due to degradation. The system is assumed to allow replacement of stacks during operation, but a minimum number of stacks in operation is needed to avoid complete shutdown. Experimental data are used in conjunction with a physics-based performance model to construct the failure probability function. A dynamic program then solves the optimization problem in terms of time and replacement requirements to minimize the total negative deviation from a given target reliability.FindingsResults show that multi-stack SOFC systems face challenges which are only revealed on a system- and not on a module-level. The main finding is that the reliability of multi-stack SOFC systems is not sufficient to serve as sole power source for critical applications such as data center.Practical implicationsThe principal methodology may be applicable to other modular systems which include multiple critical components (of the same kind). These systems comprise other electrochemical systems such as further fuel cell types.Originality/valueThe novelty of this work is the combination of mathematical modeling to solve a real-world problem, rather than assuming idealized input which lead to more benign system conditions. Furthermore, the necessity to use a mathematical model, which captures sufficient physics of the SOFC system as well as stochasticity elements of its environment, is of critical importance. Some simplifications are, however, necessary because the use of a detailed model directly in the dynamic program would have led to a combinatorial explosion of the numerical solution space.

scholarly journals A model-based approach for current voltage analyses to quantify degradation and fuel distribution in solid oxide fuel cell stacks

2015 ◽  
Vol 288 ◽  
pp. 409-418 ◽  
Author(s):  
Markus Linder ◽  
Thomas Hocker ◽  
Christoph Meier ◽  
Lorenz Holzer ◽  
K. Andreas Friedrich ◽  
...  
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Fuel Distribution ◽  
Model Based ◽  
Current Voltage

New proposal to the electrical representation of a solid oxide fuel cell

2017 ◽  
Vol 34 (3) ◽  
pp. 140-148
Author(s):  
Zbigniew Magonski ◽  
Barbara Dziurdzia
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Voltage Drop ◽  
Semiconductor Devices ◽  
Solid Oxide ◽  
Voltage Source ◽  
Oxide Fuel ◽  
Content Type ◽  
Cell Parameters ◽  
In Series

Purpose The aim of this paper is to find the electrical representation of a solid oxide fuel cell (SOFC) that enables the application of typical exploitation characteristics of fuel cells for estimation of fuel cell parameters (for example, exchange current) and easy analysis of phenomena occurred during the fuel cell operation. Design/methodology/approach Three-layer structure of an SOFC, where a thin semi-conducting layer of electrolyte separates the anode from the cathode, shows a strong similarity to typical semiconductor devices built on the basis of P-N junctions, like diodes or transistors. Current–voltage (I-V) characteristics of a fuel cell can be described by the same mathematical functions as I-V plots of semiconductor devices. On the basis of this similarity and analysis of impedance spectra of a real fuel cell, two electrical representations of the SOFC have been created. Findings The simplified electrical representation of SOFC consists of a voltage source connected in series with a diode, which symbolizes a voltage drop on a cell cathode, and two resistors. This model is based on the similarity of Butler-Volmer to Shockley equation. The advanced representation comprises a voltage source connected in series with a bipolar transistor in close to saturation mode and two resistors. The base-emitter junction of the transistor represents voltage drop on the cell cathode, and the base-collector junction represents voltage drop on the cell anode. This model is based on the similarity of Butler-Volmer equation to Ebers-Moll equation. Originality/value The proposed approach based on the Shockley and Ebers-Moll formulas enables the more accurate estimation of the ion exchange current and other fuel cell parameters than the approach based on the Butler-Volmer and Tafel formulas. The usability of semiconductor models for analysis of SOFC operation was proved. The models were successively applied in a new design of a planar ceramic fuel cell, which features by reduced thermal capacity, short start-up time and limited number of metal components and which has become the basis for the SOFC stack design.

scholarly journals An Interface Heterostructure of NiO and CeO2 for Using Electrolytes of Low-Temperature Solid Oxide Fuel Cells

Nanomaterials ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 2004
Author(s):  
Junjiao Li ◽  
Jun Xie ◽  
Dongchen Li ◽  
Lei Yu ◽  
Chaowei Xu ◽  
...  
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Ionic Conductivity ◽  
Ionic Conductivities ◽  
Solid Oxide ◽  
Electrode Polarization ◽  
Oxide Fuel ◽  
Type Semiconductor ◽  
Ceramic Fuel ◽  
Ceramic Fuel Cells

Interface engineering can be used to tune the properties of heterostructure materials at an atomic level, yielding exceptional final physical properties. In this work, we synthesized a heterostructure of a p-type semiconductor (NiO) and an n-type semiconductor (CeO2) for solid oxide fuel cell electrolytes. The CeO2-NiO heterostructure exhibited high ionic conductivity of 0.2 S cm−1 at 530 °C, which was further improved to 0.29 S cm−1 by the introduction of Na+ ions. When it was applied in the fuel cell, an excellent power density of 571 mW cm−1 was obtained, indicating that the CeO2-NiO heterostructure can provide favorable electrolyte functionality. The prepared CeO2-NiO heterostructures possessed both proton and oxygen ionic conductivities, with oxygen ionic conductivity dominating the fuel cell reaction. Further investigations in terms of electrical conductivity and electrode polarization, a proton and oxygen ionic co-conducting mechanism, and a mechanism for blocking electron transport showed that the reconstruction of the energy band at the interfaces was responsible for the enhanced ionic conductivity and cell power output. This work presents a new methodology and scientific understanding of semiconductor-based heterostructures for advanced ceramic fuel cells.

scholarly journals Off-Design Performance Analysis of a Solid-Oxide Fuel Cell/Gas Turbine Hybrid for Auxiliary Aerospace Power

2005 ◽  
Author(s):  
Joshua E. Freeh ◽  
Christopher J. Steffen ◽  
Louis M. Larosiliere
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Gas Turbine ◽  
Sea Level ◽  
Environmental Control ◽  
Power Level ◽  
Solid Oxide ◽  
System Level ◽  
Oxide Fuel ◽  
Full Power

A solid-oxide fuel cell/gas turbine hybrid system for auxiliary aerospace power is analyzed using 0-D and 1-D system-level models. The system is designed to produce 440kW of net electrical power, sized for a typical long-range 300-passenger civil airplane, at both sea level and cruise flight level (12,500m). In addition, a part power level of 250kW is analyzed at the cruise condition, a requirement of the operating power profile. The challenge of creating a balanced system for the three distinct conditions is presented, along with the compromises necessary for each case. A parametric analysis is described for the cruise part power operating point, in which the system efficiency is maximized by varying the air flow rate. The system is compared to an earlier version that was designed solely for cruise operation. The results show that it is necessary to size the turbomachinery, fuel cell, and heat exchangers at sea level full power rather than cruise full power. The resulting estimated mass of the system is 1912 kg, which is significantly higher than the original cruise design point mass, 1396 kg. The net thermal efficiencies with respect to the fuel LHV are calculated to be 42.4% at sea level full power, 72.6% at cruise full power, and 72.8% at cruise part power. The cruise conditions take advantage of pre-compressed air from the on-board Environmental Control System, which accounts for a portion of the unusually high thermal efficiency at those conditions. These results show that it is necessary to include several operating points in the overall assessment of an aircraft power system due to the variations throughout the operating profile.

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