The Effect of Gas Channels-Electrode Interface Area on SOFCs Performance

2012 ◽  
Author(s):  
Julio C. Moreno-Blanco ◽  
Francisco Elizalde-Blancas ◽  
Abel Hernandez-Guerrero ◽  
Cuauhtemoc Rubio-Arana
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cells ◽  
Three Dimensional ◽  
Current Collector ◽  
Electrical Energy ◽  
Current Collectors ◽  
Fuel Cell Performance ◽  
Cell Components ◽  
Electrode Interface ◽  
Flow Distributor

It is well known that the main overpotentials during the operation of a fuel cell are activation, ohmic and concentration overpotentials. In order to operate more efficiently these devices that convert the chemical energy of the fuel into electrical energy, it is necessary to reduce as much as possible the overpotentials aforementioned. Some of the components of a fuel cell are the so called current collectors. These components affect the fuel cell performance mainly by means of two overpotentials, the ohmic and concentration overpotentials. The second one, is however, affected indirectly by the current collector design, since it may only help to distribute more uniformly the gases over the electrodes. The activation overpotential is basically not affected because it is mainly related with the electrode properties such as the exchange current density. In this work, the effect of the current collectors design on the performance of planar Solid Oxide Fuel Cells (SOFCs) is assessed by means of fully three-dimensional numerical simulations by comparing the V-I and power density curves of a planar cell. The goal of this study is not to find the optimal design of the current collectors but a way in which the overpotentials relate with their design in order to propose some helpful recommendations during the design process of these fuel cell components. These recommendations may lead to design an improved or optimal flow distributor.

A Review of the Importance and Present Status of Micro-Tubular Solid Oxide Fuel Cells

2015 ◽  
Vol 1116 ◽  
pp. 190-201
Author(s):  
Md. Hasan Zahir
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cells ◽  
Raw Materials ◽  
Electrical Energy ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Fabrication Technology ◽  
Fuel Gas ◽  
Environmental Friendly ◽  
Cell Components

The generation of environmental-friendly energy is now one of the major demand of the world for healthy future. Fuel cell is one of the prime candidate in this regard which convert chemical energy of a fuel gas very efficiently and directly into electrical energy. This chapter describes the concept, impact of anode and electrolyte morphology, thickness, diameter, and fabrication of a micro-tubular solid oxide fuel cell (SOFC). The chapter describes the anode, cathode, and electrolyte of the cell components in more detail and their importance of each is regarding their size and thickness. Advantages of micro-tubular SOFCs with respect to the other fuel cell technologies are compared. The chapter describes the potential for directly running off hydrocarbon fuels and the design and operation of micro-tubular SOFCs on bio-fuel specifications and materials’ requirements. The chapter also discuss fabrication technology of micro-tubular single cell by using commercially available raw materials.

Modification of Results From Computational-Fluid-Dynamics Simulations of Single-Cell Solid-Oxide Fuel Cells to Estimate Multicell Stack Performance

2010 ◽  
Vol 8 (2) ◽  
Author(s):  
William J. Sembler ◽  
Sunil Kumar
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cells ◽  
Single Cell ◽  
Three Dimensional ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Cfd Model ◽  
Fuel Cell Performance ◽  
Cfd Models

A typical single-cell fuel cell is capable of producing less than 1 V of direct current. Therefore, to produce the voltages required in most industrial applications, many individual fuel cells must typically be stacked together and connected electrically in series. Computational fluid dynamics (CFD) can be helpful to predict fuel-cell performance before a cell is actually built and tested. However, to perform a CFD simulation using a three-dimensional model of an entire fuel-cell stack can require a considerable amount of time and multiprocessor computing capability that may not be available to the designer. To eliminate the need to model an entire multicell assembly, a study was conducted to determine the incremental effect on fuel-cell performance of adding individual solid-oxide fuel cells (SOFCs) to a CFD model of a multicell stack. As part of this process, a series of simulations was conducted to establish a CFD-nodal density that would not only produce reasonably accurate results but could also be used to create and analyze the relatively large models of the multicell stacks. Full three-dimensional CFD models were then created of a single-cell SOFC and of SOFC stacks containing two, three, four, five, and six cells. Values of the voltages produced when operating with various current densities, together with temperature distributions, were generated for each of these CFD models. By comparing the results from each of the simulations, adjustment factors were developed to permit single-cell CFD results to be modified to estimate the performance of stacks containing multiple fuel cells. The use of these factors could enable fuel-cell designers to predict multicell stack performance using a CFD model of only a single cell.

Development of a Silver Based Stable Current Collector for Solid Oxide Fuel Cell Cathodes

2012 ◽  
Vol 1385 ◽  
Author(s):  
Ayhan Sarikaya ◽  
Vladimir Petrovsky ◽  
Fatih Dogan
Keyword(s):  
Fuel Cell ◽  
Low Cost ◽  
Current Collector ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Lanthanum Strontium Manganite ◽  
Current Collectors ◽  
Long Term Stability ◽  
Cell Components ◽  
Porous Microstructure

ABSTRACTLong term stability has been a crucial issue for the future applications of the solid oxide fuel cells (SOFCs). Current collectors for the cathodes have been among the most vulnerable components of the SOFCs due to their operation in oxidizing atmospheres at relatively high temperatures. Ag and Ag based LSM (lanthanum-strontium manganite) composites were studied to develop highly stable and low-cost current collectors compatible with other fuel cell components. In this study, no degradation was observed in the electrical conductivity and the porous microstructure of the Ag-LSM composite current collectors after 600 hours of operation at 800oC in air.

Hybrid Direct Carbon Fuel Cell Performance With Anode Current Collector Material

2015 ◽  
Vol 12 (6) ◽  
Author(s):  
Lisa Deleebeeck ◽  
Kent Kammer Hansen
Keyword(s):  
Catalytic Activity ◽  
Fuel Cell ◽  
Current Collector ◽  
Anode Current ◽  
Molten Carbonate ◽  
Current Collectors ◽  
Fuel Cell Performance ◽  
Carbonate Carbon ◽  
Direct Carbon Fuel Cell ◽  
Current Voltage

The influence of the current collector on the performance of a hybrid direct carbon fuel cell (HDCFC), consisting of solid oxide fuel cell (SOFC) with a molten carbonate–carbon slurry in contact with the anode, has been investigated using current–voltage curves. Four different anode current collectors were studied: Au, Ni, Ag, and Pt. It was shown that the performance of the direct carbon fuel cell (DCFC) is dependent on the current collector materials, Ni and Pt giving the best performance, due to their catalytic activity. Gold is suggested to be the best material as an inert current collector, due to its low catalytic activity.

3-D Model of Proton Exchange Membrane Fuel Cells

2000 ◽  
Author(s):  
Tianhong Zhou ◽  
Hongtan Liu
Keyword(s):  
Fuel Cell ◽  
Proton Exchange Membrane ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Pem Fuel Cell ◽  
Proton Exchange ◽  
Three Dimensional Model ◽  
Chemical Reaction Kinetics ◽  
Fuel Cell Performance ◽  
D Model

Abstract A comprehensive three-dimensional model for a proton exchanger membrane (PEM) fuel cell is developed to evaluate the effects of various design and operating parameters on fuel cell performance. The geometrical model includes two distinct flow channels separated by the membrane and electrode assembly (MEA). This model is developed by coupling the governing equations for reactant mass transport and chemical reaction kinetics. To facilitate the numerical solution, the full PEM fuel cell was divided into three coupled domains according to the flow characteristics. The 3-D model has been applied to study species transport, heat transfer, and current density distributions within a fuel cell. The predicated polarization behavior is shown to compare well with experimental data from the literature. The modeling results demonstrate good potential for this computational model to be used in operation simulation as well as design optimization.

Gas Flow and Heat Transfer Analysis for an Anode Duct in Reduced Temperature SOFCs

2003 ◽  
Author(s):  
Jinliang Yuan ◽  
Masoud Rokni ◽  
Bengt Sunde´n
Keyword(s):  
Heat Transfer ◽  
Fuel Cell ◽  
Porous Layer ◽  
Gas Flow ◽  
Porous Electrode ◽  
Three Dimensional ◽  
Gas Permeation ◽  
Heat Transfer Analysis ◽  
Fuel Cell Performance ◽  
Flow And Heat Transfer

In this study, a fully three-dimensional calculation method has been further developed to simulate and analyze various processes in a thick anode duct. The composite duct consists of a porous layer, the flow duct and solid current connector. The analysis takes the electrochemical reactions into account. Momentum and heat transport together with gas species equations have been solved by coupled source terms and variable thermo-physical properties (such as density, viscosity, specific heat, etc.) of the fuel gases mixture. The unique fuel cell conditions such as the combined thermal boundary conditions on solid walls, mass transfer (generation and consumption) associated with the electrochemical reaction and gas permeation to / from the porous electrode are applied in the analysis. Results from this study are presented for various governing parameters in order to identify the important factors on the fuel cell performance. It is found that gas species convection has a significant contribution to the gas species transport from / to the active reaction site; consequently characteristics of both gas flow and heat transfer vary widely due to big permeation to the porous layer in the entrance region and species mass concentration related diffusion after a certain distance downstream the inlet.

scholarly journals Evaluation of Bi2V0.9Cu0.1O5.35—an Aurivillius-Type Conducting Oxide—as a Cathode Material for Single-Chamber Solid-Oxide Fuel Cells

2010 ◽  
Vol 7 (2) ◽  
Author(s):  
Zongping Shao ◽  
Jennifer Mederos ◽  
Chan Kwak ◽  
Sossina M. Haile
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cells ◽  
Cathode Material ◽  
Sharp Decrease ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Single Chamber ◽  
Ion Conductor ◽  
Fuel Cell Performance

The compound Bi2V0.9Cu0.1O5.35, a typical Aurivillius-type fast oxygen ion conductor, was evaluated as a possible cathode material for single-chamber solid-oxide fuel cells operated under mixed propane and oxygen. The material was found to be structurally stable under various C3H8+O2 environments over a wide temperature range and furthermore displayed low catalytic activity for propane oxidation. However, at temperatures above 650°C, detrimental reactions between the cathode and the ceria electrolyte occurred, producing low conductivity interfacial phases. At these high temperatures the cathode additionally underwent extensive sintering and loss of porosity and, thus, stable fuel cell operation was limited to furnace temperatures of <600°C. Even under such conditions, however, the partial oxidation occurring at the anode (a ceria nickel cermet) resulted in cell temperatures as much as 70–110°C higher than the gas-phase temperature. This explains the sharp decrease in fuel cell performance with time during operation at a furnace temperature of 586°C. Under optimized conditions, a peak power density of ∼60 mW/cm2 was obtained, which does not compete with recent values obtained from higher activity cathodes. Thus, the poor electrochemical activity of Bi2V0.9Cu0.1O5.35, combined with its chemical instability at higher temperatures, discourages further consideration of this material as a cathode in single-chamber fuel cells.

Structural and Electrochemical Studies on Thin-Film Yttria-Doped Zirconia Electrolytes for Microscale Solid Oxide Fuel Cells

2008 ◽  
Author(s):  
Alex C. Johnson ◽  
Shriram Ramanathan
Keyword(s):  
Thin Film ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cells ◽  
Solid Oxide ◽  
Platinum Electrodes ◽  
Electrochemical Studies ◽  
Oxide Fuel ◽  
Conductivity Measurements ◽  
Fuel Cell Performance ◽  
Pt Electrodes

We report in-plane and through-plane conductivity measurements of dense YSZ films varying in thickness from 20 to 200 nm. In-plane measurements were performed on YSZ films grown on silicon wafers coated with SiO2 or Si3N4. Micro-fabricated strips with Pt electrodes in various geometries were used to obtain conductivity as a function of temperature from 200 – 600 °C in a custom-designed micro-probe station. These films have activation energies, which vary from 0.77 to 1.09 eV. Their absolute conductivity is lower compared with other reports. Through-plane and fuel cell measurements were performed by depositing YSZ on a nitrided silicon wafer, then etching through the wafer and depositing porous platinum electrodes on both sides [6,7]. We discuss the electrochemical conduction studies in detail along with fuel cell performance and correlation with electrode microstructure.

Effect of Anode and Cathode Current-Collector Structure on Performance of a Passive Direct Methanol Fuel Cell

2011 ◽  
Vol 347-353 ◽  
pp. 3275-3280 ◽  
Author(s):  
Xian Qi Cao ◽  
Ji Tian Han ◽  
Ze Ting Yu ◽  
Pei Pei Chen
Keyword(s):  
Fuel Cell ◽  
Direct Methanol Fuel Cell ◽  
Current Collector ◽  
Cell Voltage ◽  
Methanol Concentration ◽  
Membrane Area ◽  
Fuel Cell Performance ◽  
Direct Methanol ◽  
Cathode Current ◽  
Methanol Fuel Cell

In this work, the effect of the current-collector structure on the performance of a passive direct methanol fuel cell (DMFC) was investigated. Parallel current-collector (PACC) and other two kinds of perforated current collectors (PECC) were designed, fabricated and tested. The studies were conducted in a passive DMFC with active membrane area of 9 cm2, working at ambient temperature and pressure. Two kinds of methanol solution of 2 M and 4 M were used. Results showed that the PACC as anode current-collector has a positive effect on cell voltage and power. For the cathode current-collector structure, the methanol concentration of 2 M for PECC-2 (higher open ratio 50.27 %) increased performance of DMFC. But the methanol concentration of 4 M led to an enhancement of fuel cell performance that used PACC or PECC-2 as cathode current-collector.

CFD Simulations of Flow and Pressure Distributions in Column Flow Type Fuel Cells

2006 ◽  
Author(s):  
Paul Ridenour ◽  
Zhigi Ma ◽  
Naresh Kumar Selvarasu ◽  
Eugene S. Smotkin ◽  
Chenn Q. Zhou
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Flow Rate ◽  
New Technology ◽  
Volumetric Flow Rate ◽  
Electrical Energy ◽  
Pressure Drops ◽  
Fuel Cell Performance ◽  
Pressure Distributions ◽  
Flow Channels

Fuel cells are a growing new technology that can be applied in order to harness electrical energy out of hydrogen and hydrated air. When testing these devices however, pressure drops along the apparatus are strongly discouraged due to the fluctuation in gas volumetric flow rate that they incur. The design of the flow channels is critical to the fuel cell performance and water management. In this research, computational fluid dynamics (CFD) is used to analyze the gas manifold and a column channel inside of a fuel cell. The effect of the flow channel parameters on the flow rate and pressure drops are investigated to provide useful information to optimize the design of flow channels.

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