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Proceedings Article (75)
Low Temperature Fuel Cell Technologies (10)
Modeling, Design, and Optimization for Low Temperature Fuel Cells (7)
High Temperature Fuel Cell Technologies (5)
Transportation Systems (5)
Material and Fabrication Processes (4)
Modeling, Design, and Optimization for High Temperature Fuel Cells (4)
Cell, Stack and System Modeling (3)
Design, Integration and Balance of Plant of Electrochemical Systems (3)
Portable Systems (3)
Materials for High Temperature Fuel Cells (2)
Power density (75)
Fuel cells (44)
Fuels (34)
Solid oxide fuel cells (34)
Anodes (26)
Flow (Dynamics) (24)
Temperature (24)
Electrodes (19)
Electrolytes (15)
Power density
Active Control of Stack Inlet and Outlet Coolant Temperature for the PEM Fuel Cell System
Fengxiang Chen, Jieran Jiao, Yang Yu, Yuan Gao, Sichuan Xu
Proc. ASME. FUELCELL2017, ASME 2017 15th International Conference on Fuel Cell Science, Engineering and Technology, V001T01A001, June 26–30, 2017
Paper No: FUELCELL2017-3197
DOI: https://doi.org/10.1115/FUELCELL2017-3197
With the advantages of high power density, rapid startup, low operating temperature and no emission of pollutants, proton exchange membrane (PEM) fuel cell is considered to be the most promising candidate for the next generation power source of Clean Energy Automotive. PEM fuel cell operation necessitates thermal management to satisfy the requirements of safe and efficient operation by keeping the temperature within a certain range independent of varying load conditions. As for a high power PEM fuel cell system (eg. 80kw) without the external gas to gas humidifier, the temperature of the stack inlet coolant had better track to a time-varying curve produced by the working condition, which introduce the temperature difference between the cathode inlet and outlet, and thus it improves the relative humidity of the inlet air of the cathode. Compared to the traditional stack outlet coolant temperature regulation problem, the new plant is a two inputs and two outputs system, furthermore, the stack inlet coolant temperature control is a tracking problem which is different to the outlet coolant temperature regulation (regulation problem). Considering that the PEM fuel cell without the external humidifier is a promising scheme which has been adopted by the Mirai fuel cell vehicle [1], we actively aim to control both the inlet and outlet coolant temperature as desired simultaneously. In this paper, a two inputs and two outputs decouple control scheme is developed to achieve our aim. Firstly, based on the energy conservation and continuity equation, we establish a dynamic thermal model for the cooling system consisted of a water circulation pump and a radiator coupled to a fan, integrated with the fuel cell stack. Secondly, the static coupling characteristics of the control variable is analyzed according the relative gain matrix method. Then two specific control strategies are designed. One is based on frequency domain pure PID control technique. Considering the coupling phenomenon between two control channels, another technique is based on decouple theory feed-forward decouple control technique. Both of them try to regulate the outlet and inlet coolant temperature through tuning mass flow rate of water circulation pump and duty ratio of radiator. Finally, all the control strategies are demonstrated on the platform of Matlab / Simulink. The results show that both of them can control the stack inlet and outlet coolant temperature simultaneously, but the second strategy has much better performance than the first.
Topics: Coolants, Proton exchange membrane fuel cells, Temperature, Temperature control, Fuel cells, Humidifiers, Proton exchange membranes, Pumps, Water, Cooling systems
Flame-Assisted Fuel Cell Operating With Methane for Combined Heating and Micro Power
Ryan Milcarek, Kang Wang, Ryan Falkenstein-Smith, Jeongmin Ahn, H. E. Khalifa
Proc. ASME. FUELCELL2015, ASME 2015 13th International Conference on Fuel Cell Science, Engineering and Technology, V001T03A003, June 28–July 2, 2015
Paper No: FUELCELL2015-49353
DOI: https://doi.org/10.1115/FUELCELL2015-49353
Solid Oxide Fuel Cells (SOFCs) operating in a Flame-assisted Fuel Cell (FFC) setup have potential for Combined Heating and micro Power applications. The feasibility of a FFC furnace operating with natural gas is investigated by using methane/ air flames. The confrontation between the FFCs operating temperature and fuel concentration under various conditions was investigated which uncovered the complex performance behavior. Variations in the fuel/ air equivalence ratio, fuel flow rate and distance between the FFC anode and burner outlet were studied. A critical distance for FFC placement above the burner outlet was uncovered, which has a significant impact on the FFCs performance. A high power density of 791mW.cm −2 was achieved which is comparable to the dual chamber SOFC and single chamber SOFC. Carbon coking was observed on the anode surface, but was not detrimental to FFC performance during testing.
Topics: Flames, Fuel cells, Heating, Methane, Solid oxide fuel cells, Fuels, Anodes, Carbon, Flow (Dynamics), Furnaces
Comparisons of Performances and Liquid Water Distributions Within Bio-Inspired and Single-Serpentine PEM Fuel Cell Channels
Bhaskar P. Saripella, Umit O. Koylu, Ming C. Leu
Flow field design in Proton Exchange Membrane (PEM) fuel cells is a major area of research for performance improvement. Bio-inspired flow field designs are a relatively recent development in fuel cell technology evolution. These novel designs have potential for performance improvements by effective distribution of reactant gases with better water management capabilities. This work investigates the performance and water distribution in a bio-inspired flow field design, formulated using Murray's law and mimicking a typical leaf venation pattern, in comparison to a conventional single serpentine design. Experiments were conducted using a transparent fuel cell with copper as the conductive channel and current collector. The results indicated the superior performance of the bio-inspired design with a 30% increase in peak power density in comparison to the single serpentine design. Additionally, the flow regimes based on two-phase flows in micro channels were identified and their effects on fuel cell stability were determined.
Topics: Biomimetics, Proton exchange membrane fuel cells, Water, Design, Flow (Dynamics), Fuel cells, Proton exchange membranes, Copper, Fuel cell technology, Gases
GDC Electrolytes With Patchwork Type Morphology and Their Microtubular SOFC Applications
Md. Hasan Zahir, Haitham Bahaidarah
A patchwork type morphology was formed due to an accidental addition of excess polyvinyl butyral (PVB) polymer powder into the Gadolinia doped Ceria (GDC) slurries during the preparation of homogeneous slurries by a wet atomization process. GDC thin layer has been fabricated on the top of porous tubular anode (GDC-NiO) support at 1400 °C. The results of this study show that polymer can be used not only to fabricate a dense electrolyte but also to generate a nanoporous grain boundary. The fabricated electrolytes have been tested for SOFC (Solid Oxide Fuel Cell) applications in the intermediate-temperature region. The single-cell with dense electrolytes performance test showed a high power density at 550 °C with wet H 2 fuel. The effect of different polymers, such as polyvinyl pyrrolidinone (PVP) and polytetrafluoroethylene (PTFE), into the electrolyte slurry was also tested. The polymer binder used in preparing GDC slurry is preferably neither PVP nor PTFE, and/or contains no amounts of these polymers.
Topics: Electrolytes, Solid oxide fuel cells, Polymers, Slurries, Anodes, Binders (Materials), Fuels, Grain boundaries, Power density, Temperature
Integrated Anaerobic Digester and Fuel Cell Power Generation System for Community Use
Ryan Falkenstein-Smith, Kang Wang, Ryan Milcarek, Jeongmin Ahn
New York State is expected to experience future population growth that is increasingly concentrated in urban areas, where there is already a heavy burden on the existing energy, water and waste management infrastructure. To meet aggressive environmental standards (such as that established by the State's "80x50" goal), future electrical power capacity must produce substantially fewer greenhouse gas emissions than currently generated by coal- or natural gas-fired power plants. Currently, biogas is combusted to produce heat and electricity via an internal combustion engine generator set. A conventional internal combustion engine generator set is 22–45 % efficient in converting methane to electricity, thus wasting 65–78 % of the biogas energy content unless the lower temperature heat can be recovered. Fuel cells, on the other hand, are 40–60 % efficient in converting methane to electrical energy, and 80–90 % efficient for cogeneration if heat (> 400 °C) is recovered and utilized for heating and cooling in the community power system. This current research studies the feasibility of a community biomass-to-electricity power system which offers significant environmental, economic and resilience improvements over centrally-generated energy, with the additional benefit of reducing or eliminating disposal costs associated with landfills and publicly-owned treatment works (POTWs). Flame Fuel Cell (FFC) performance was investigated while modifying biogas content and fuel flow rate. A maximum power density peak at 748 mWcm-2 and an OCV of 0.856 V was achieved. It should be noted that the performance obtained with the model biofuel is comparable to the performances of direct methane fueled DC-SOFC and SC-SOFC. The common trends also concluded an acceptable range for optimal performance. Although the methane to CO2 ratios of 3:7 and 2:8 produced power, they are not the strongest ratios to have optimal performance, meaning that operation should stay between the 6:4/4:6 ratio range. Lastly, the amount of air added to the biogas mixture is crucial to achieving the optimal performance of the cell. The data obtained confirmed the feasibility of a biofuel driven fuel cell CHP device capable of achieving higher efficiency than existing technologies. The significant power output produced from the sustainable biogas composition is competitive with current hydrocarbon fuel sources. This idea can be expanded for a community waste management infrastructure.
Topics: Energy / power systems, Fuel cells, Biogas, Methane, Heat, Biofuel, Combined heat and power, Fuels, Generators, Internal combustion engines
Model-Based Analysis of Electrode Design in a Direct Methanol Microscale Fuel Cell
Adam S. Hollinger, Michael G. Willis, Daniel G. Doleiden
The performance of microscale fuel cells with high-aspect-ratio electrodes, defined as the ratio of electrode length to width, is often limited by the depletion of fuel along the length of the anode. Here we present a mathematical model to study electrode aspect ratio in a direct methanol microscale fuel cell. The model is supported with experimental data to show that low-aspect-ratio electrodes achieve higher power densities via improved mass transport to electrodes. The influence of electrode width on overall cell performance was investigated by varying the catalyst deposition region in low-aspect-ratio electrodes. The performance of our experimental fuel cell is consistent with our modeling studies, achieving a maximum power density of 25.3 mW/cm 2 at room temperature with 1 M methanol. The model presented here can be used to further improve the geometric design of electrodes in a microscale fuel cell.
Topics: Design, Electrodes, Fuel cells, Methanol, Microscale devices, Anodes, Catalysts, Fuels, Modeling, Power density
Development of Solid Oxide Fuel Cell to Collect Electricity From Exhaust Gas
Keigo Onita, Kiyoshi Yanagihara, Rikimaru Yamada, Youhei Nakagawa
Exhaust gas of internal combustion engine contains carbon-oxide and hydrocarbon. The temperature of these gases which are emitted in atmosphere are higher than 873 K. In the environment under the high-temperature gas. Reforming of Steam Methane Reforming, Water-Gas Shift Reaction and Carbon Precipitation are expected in the exhaust pipe. This environment of the exhaust-gases accommodates with operating environment of Solid Oxide Fuel Cell (SOFC). Therefore, if electricity can be collected from such exhaust gas environment, engine system can utilize smaller AC generator and battery, and if the gas reforming and electrochemical reactions can clean the exhaust gases, that can lead to disuse catalyzer. Those also can accomplish lighter engine system and totally efficiency of engine system. Therefore, in order to collect electricity from exhaust gas, the single type SOFC unit is designed and installed in the exhaust pipe of 110cc engine of a small motorcycle. Various experiments are executed in this paper. The experimental results show that the developed SOFC-unit works, and power density of about 8.5mW/cm 2 is obtained.
Topics: Exhaust systems, Solid oxide fuel cells, Engines, Gases, Carbon, Batteries, Electrochemical reactions, Generators, High temperature, Internal combustion engines
Power Generation From Thermal Transpiration Based Pumping Devices
Pingying Zeng, Kang Wang, Ryan Falkenstein-Smith, Jeongmin Ahn, Paul D. Ronney
This study examines the successful development of a combustion-driven thermal transpiration-based combustor and a self-sustaining gas pump system having no moving parts and using readily storable hydrocarbon fuel. A stacked configuration was then integrated into the combustor creating a self-sustaining power generation system. In recent years, power generation devices employing hydrocarbon fuels rather than electrochemical storage as energy feedstock have been studied extensively due to the much higher energy densities of hydrocarbon fuels than the best available batteries. While many devices have been proposed including internal combustion engines and gas turbines, they all require the use of air to obtain a higher energy density so that only one reactant (fuel) need be carried. Thermal transpiration was accomplished by meeting two essential conditions: (1) gas flow in the transitional or molecular regime using glass microfiber filters as transpiration membranes and (2) a temperature gradient through the membrane using catalytic combustion downstream of the membrane. A cubic combustor was designed to house the thermal transpiration membrane and develop into a self-sustaining gas pump system. Fuel/Air would feed through an inlet into a mixing chamber that would flow into the thermal guard containing the thermal transpiration membrane. The thermal guard was developed from a high thermal conductivity stainless steel made into a cubic formation by using a 3D printing process. This configuration allowed both fuel and air to be transpired through the membrane meaning it was not possible for any reactant flow to occur as a result of the fuel supply pressure and only the membrane could draw reactants into the device. In addition to pumping, a single-chamber solid-oxide fuel cell (SC-SOFC) was incorporated into combustion driven thermal transpiration pumps to convert chemical or thermal energy into electrical energy for a self-contained portable power generation system. Experiments showed that transpiration pumps with larger porosity and larger overall size exhibited better performance, though membrane pore size had little effect. These results were quantitatively consistent with theoretical predictions. By exploiting the temperature and fuel/oxygen concentrations within the transpiration pump, the SOFC achieved a maximum power density of 40 mW/cm2. Despite being far lower than necessary for a power source to be competitive with batteries, this preliminary study signifies an on-going positive efficiency that has potential for improvement through optimizing SOFC technology.
Topics: Energy generation, Transpiration, Fuels, Membranes, Pumps, Solid oxide fuel cells, Combustion, Combustion chambers, Energy / power systems, Flow (Dynamics)
Saint-Gobain's All Ceramic SOFC Stack: Architecture and Performance
Robin Barabasz, Emma Dutton, Brian Feldman, Guangyong Lin, Aravind Mohanram, Yeshwanth Narendar, John Pietras, Frank Chunming Qi, Zachary Patterson, Sophie Poizeau, Ayhan Sarikaya, Morteza Zandi
Saint-Gobain has developed a unique all ceramic SOFC stack with performance characteristics that make it an attractive solution to the cost and durability challenges of commercializing conventional SOFCs. Saint-Gobain's all ceramic stacks achieve power density higher than 200 mW/cm 2 when operating at 800 °C and 0.75 V/cell. Power degradation is low at <0.2% per kilohour over more than 12,000 hours of testing. Ceramic interconnect stability is verified for >16,000 hours using accelerated testing. Good performance under thermal cycling, power cycling and unplanned transients such as fuel or air loss has also been confirmed. With reliable R&D scale manufacturing and targeted testing platforms, Saint-Gobain has increased sub-scale stack power density by 61% and decreased interconnect cell resistance by 65% with further improvements in development.
Topics: Ceramics, Solid oxide fuel cells, Testing, Power density, Durability, Fuels, Manufacturing, Performance characterization, Stability, Transients (Dynamics)
Exergogravimetric Design for Increased SOFC System Power Density
Comas Haynes, Ryan Miller
Proc. ASME. FUELCELL2013, ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology, V001T02A003, July 14–19, 2013
Compact subsystems are pivotal to aeronautical applications, inclusive of advanced energy concepts. Regarding size minimization, an "exergogravimetric" approach has recently begun that attempts an exergy-aided weight reduction of advanced energy systems (inclusive of fuel); and this is based upon the added design insights afforded by Second Law considerations. The chief rationale and objective are to leverage the advancements that exergoeconomics affords in the realm of cost-effective thermal system design to aid size-effective thermal system design. A conceptual solid oxide fuel cell (SOFC) system for long-duration unmanned aerial vehicle (UAV) applications has been initially modeled and simulated, inclusive of exergy analysis, and preliminary findings are discussed. Additionally, the concepts and methodologies can be extended to other advanced energy system technologies. There are project-specific and general milestones and conclusions drawn from the initial investigation. Specific to the project, a conceptual SOFC system simulation was completed via physics-based and literature-verified models along with structured language (i.e., MATLAB) numerical implementation. Specific component-level contributions to lost power potential and added mass were preliminarily resolved. Thermal exergy destruction and loss are predominant sources of unutilized specific power potential. Operational and physical degrees-of-freedom were explored, with the aid of exergy analysis, to resolve better design pathways. This included a counterintuitive preliminary finding that larger cell interconnects may facilitate smaller and more efficient system operation. Generally, exergy analyses allow a system design opportunity to gain higher resolution insights (i.e., to component- and spatial-extents) regarding inefficiencies throughout a thermal system, and this is afforded by the comprising blend of 1 st Law and 2 nd Law considerations. There is also an added means of accounting for 2 nd Law effects. The traditional 2 nd Law verification point of entropy generation being non-negative does not provide the same level of process analysis closure as does the related constraint that all processes have to account for exergy being stored, converted, destroyed or rejected through any defined control volume. This alternative 2 nd Law perspective facilitates verification and validation of simulations.
Topics: Design, Power density, Solid oxide fuel cells, Exergy, Exergy analysis, Thermal systems, Simulation, Unmanned aerial vehicles, Accounting, Degrees of freedom
Using Shewanella Oneidensis MR1 as a Biocatalyst in a Microscale Microbial Fuel Cell
Jie Yang, Sasan Ghobadian, Reza Montazami, Nastaran Hashemi
Microbial fuel cell (MFC) technology is a promising area in the field of renewable energy because of their capability to use the energy contained in wastewater, which has been previously an untapped source of power. Microscale MFCs are desirable for their small footprints, relatively high power density, fast start-up, and environmentally-friendly process. Microbial fuel cells employ microorganisms as the biocatalysts instead of metal catalysts, which are widely applied in conventional fuel cells. MFCs are capable of generating electricity as long as nutrition is provided. Miniature MFCs have faster power generation recovery than macroscale MFCs. Additionally, since power generation density is affected by the surface-to-volume ratio, miniature MFCs can facilitate higher power density. We have designed and fabricated a microscale microbial fuel cell with a volume of 4 μL in a polydimethylsiloxane (PDMS) chamber. The anode and cathode chambers were separated by a proton exchange membrane. Carbon cloth was used for both the anode and the cathode. Shewanella Oneidensis MR-1 was chosen to be the electrogenic bacteria and was inoculated into the anode chamber. We employed Ferricyanide as the catholyte and introduced it into the cathode chamber with a constant flow rate of approximately 50 μL/hr. We used trypticase soy broth as the bacterial nutrition and added it into the anode chamber approximately every 15 hours once current dropped to base current. Using our miniature MFC, we were able to generate a maximum current of 4.62 μA.
Topics: Fuel cells, Microscale devices, Anodes, Energy generation, Power density, Bacteria, Carbon, Catalysts, Density, Electric power generation
A Compact Versatile Microbial Fuel Cell From Paper
Luke T. Wagner, Niloofar Hashemi, Nastaran Hashemi
Microbial fuel cells (MFCs) have been a potential green energy source for a long time but one of the problems is that either the technology must be used on a large scale or special equipment have been necessary to keep the fuel cells running such as syringe pumps. Paper-based microbial fuel cells do not need to have a syringe pump to run and can run entirely by themselves when placed in contact with the fluids that are necessary for it to run. Paper-based microbial fuel cells are also more compact than traditional MFCs since the device doesn't need any external equipment to run. The goal of this paper is to develop a microbial fuel cell that does not require a syringe pump to function. This is done by layering chromatography paper with wax design printed onto it. This restricts the fluids to a specific flow path allowing it to act like the tubes in a typical microbial fuel cell device by delivering the fluids to the chamber. The fluids are picked up by tabs that sit in the fluid and use capillary attraction to flow up the tab and into the device. The fluids are directed to the chambers where the chemical and biological processes take place. These flows are then directed out of the device so that they are taken to a waste container and out of the system. Our microliter scale paper-based microbial fuel cell creates a significant current that is sustained for a period of time and can be repeated. A paper-based microbial fuel cell also has a fast response time. These results mean that it could be possible for a set of paper-based microbial fuel cells to create a power density capable of powering small, low power circuits when used in series or parallel. In this paper, we discuss the fabrication and experimental results of our paper-based microbial fuel cell. Also there will be a discussion of how paper-based microbial fuels cells compare to the traditional microbial fuel cells and how they could be used in the future.
Topics: Fuel cells, Fluids, Flow (Dynamics), Pumps, Circuits, Containers, Design, Fuels, Manufacturing, Power density
An Innovative Three Dimensional Numerical Model for Bipolar Plates to Enhance the Efficiency of PEM Fuel Cells
Faraz Arbabi, Ramin Roshandel
Proc. ASME. FUELCELL2012, ASME 2012 10th International Conference on Fuel Cell Science, Engineering and Technology, 351-360, July 23–26, 2012
The efficiency of proton exchange membrane (PEM) fuel cell is straightly correlated to the bipolar plate design and fluid channel arrangements. Higher produced energy can be attained by optimal design of type, size, or patterns of the channels. Previous researches showed that the bipolar plate channel design has a considerable effect on reactant distribution uniformity as well as humidity control in PEM fuel cells. This paper concentrates on enhancements in the fuel cell performance by optimization of bipolar plate design and channels configurations. A numerical model of flow distribution based on Navier-Stokes equations using individual computer code is presented. The results gained from this three dimensional, multi-component simulation showed excellent agreement with the existed experimental data in the previous publications. In this paper, a new flow field design inspired from the nature is presented and analyzed. In this work, two mostly used flow channels design — serpentine and parallel — have been studied and compared to the newly introduced bio inspired bipolar plate design. To compare, velocity distributions of fluid, mass fraction of reactant gases and polarization curves for different bipolar plate designs have been analyzed. The key design criteria in this study are based on more homogenous molar spreading of species and more uniform velocity distribution along the flow channels and also higher voltage and power density output in different current densities. By developing a numerical code it was concluded that the bio inspired bipolar plate can enhance the PEM fuel cell performance especially at middle current densities, where the losses caused by mass transport limitations are not significant.
Topics: Computer simulation, Plates (structures), Proton exchange membrane fuel cells, Design, Flow (Dynamics), Biomimetics, Fluids, Fuel cells, Proton exchange membranes, Computers
Performance Improvement of a Circular MCFC Through Optimal Design of the Fluid Distribution System
Adriano Sciacovelli, Vittorio Verda, Cristina Amelio, Carlo Repetto, Gustavo Diaz
Proc. ASME. FUELCELL2011, ASME 2011 9th International Conference on Fuel Cell Science, Engineering and Technology, 381-389, August 7–10, 2011
In this paper, the prototype of a circular Molten Carbonate Fuel Cell (MCFC) built in the laboratories of FN SpA Nuove Tecnologie e Servizi Avanzati is analyzed using a tridimensional computational fluid dynamic (CFD) model. The prototype is the result of FN and Politecnico di Torino activities developed for the Italian National Agency for New Technologies, Energy and Sustainable Economic Development (ENEA) within the framework of Ministry of Economic Development, MSE-ENEA. This model considers heat, mass and current transfer as well as chemical and electrochemical reactions. The results show that some inhomogeneous distributions in the reactants, causing non-optimal use of the reactant surfaces. An effective way to improve the distribution in current density consists in tracing tree shaped channels on the surface onto the distribution porous medium. In this paper Y shaped channels are adopted to improve the distribution of gas within the fuel cell and consequently to enhance the performance of the original design of the fuel cell. In addition, the configuration of the outlet of the anodic compartment is also investigated in order to further increase the performance of the fuel cell. The geometrical parameter identifying the topology of distribution channels are chosen accordingly to the constructal theory. The results show that significant improvements can be achieved. Power density is increased of about 6% when the tree-shaped channel is adopted. If a double anodic inlet is also considered the enhancement in the power density is of about 11% with respect to the initial configuration.
Topics: Design, Fluids, Molten carbonate fuel cells, Fuel cells, Computational fluid dynamics, Engineering prototypes, Power density, Current density, Electrochemical reactions, Heat
Toward Carbon Foam Structures in a Microfluidic Fuel Cell
D. Fuerth, A. Bazylak
In this paper, the design and performance of a flow-through microfluidic fuel cell with carbon-based electrodes is presented. Our preliminary results include the use of Toray TGP-H-090 carbon paper as our porous carbon electrodes. The cell exhibited a maximum power density of 0.12 mW/cm 2 and an open cell potential of 1.2 V, and a discussion of this performance is provided. The vanadium redox species is employed as fuel (V 2+ ) and oxidant (VO 2 + ) due to its ability to naturally react on bare carbon, eliminating the need for additional catalysts. Our future work will include the investigation of carbon foam electrodes with grades of 45, 80, and 100 pores per linear inch (PPI).
Topics: Carbon, Fuel cells, Microfluidics, Electrodes, Catalysts, Design, Flow (Dynamics), Fuels, Power density
The Role of Channel Plurality in Two-Phase Flow Instabilities in PEM Cathode Channels
Nicholas Siefert, Colin O'Shea, Shawn Litster
Water management is a critical issue in the development of proton exchange membrane (PEM) fuel cells with robust operation. Liquid water can accumulate and flood the gas delivery microchannels and the porous electrodes within PEM fuel cells and deteriorate performance. Since the liquid distribution fluctuates in time for two-phase flow, the rate of oxygen transport to the cathode catalyst layer also fluctuates, resulting in unstable power density and efficiency. In previous research into measuring the voltage loss and voltage fluctuation due to two-phase flow instabilities in the cathode channels of PEM fuel cells, we investigated the effect of the number of parallel channels covering the active area by studying flow fields with varying numbers of parallel channels (4 to 25) while keeping the active area constant at 5 cm 2 . The resulting voltage loss and fluctuation measurements were expressed as functions of two non-dimensional parameters: channel plurality and the air flow stoichiometric ratio. Channel plurality is a flow field design parameter that defines the number of channels per unit of active area, which is non-dimensionalized by the cross-sectional area of the channels. In this paper, we expand upon our prior studies by studying cathode flow field designs of varying active area, from 5 cm 2 to 25 cm 2 , with a constant number of 25 channels. By increasing the active area with a constant number of channels, we are reducing the channel plurality value. The new results are mapped back to the non-dimensional parameters to extract empirical scaling rules for voltage loss and fluctuation. Furthermore, we compare this data to our prior work with constant active area and identify the significance of the fuel cell size in the scaling relationships. Finally, a refined scaling is presented for generalizing the results for fuel cells having different active area and number of channels.
Topics: Proton exchange membranes, Two-phase flow, Flow (Dynamics), Fuel cells, Proton exchange membrane fuel cells, Air flow, Catalysts, Design, Electrodes, Floods
Air-Breathing Membraneless Laminar Flow Fuel Cell With Flow-Through Anode
Seyed Ali Mousavi Shaegh, Nam-Trung Nguyen, Siew Hwa Chan
This paper reports the fabrication and characterization of a new concept of flow-through anode for membraneless laminar flow fuel cell (LFFC). To establish a reference case, a fuel cell with flow over and planar anode was fabricated as well. Experimental results indicated that maximum power density was improved from 17 mW/cm 2 in planar design to 23 mW/cm 2 using the flow-through design. The higher power density of flow-through design is an indicative of higher fuel utilization in the porous anode. Images of the flow obtained experimentally showed that mixing was reduced at the liquid-liquid interface in the channel with flow-through anode leading to increased fuel concentration over anode.
Topics: Anodes, Flow (Dynamics), Fuel cells, Laminar flow, Design, Fuels, Power density, Manufacturing
Effect of the Microstructure of Porous Composite Electrodes on the Electric Power Density of Solid Oxide Fuel Cells
Siamak Farhad, Feridun Hamdullahpur
The electric power density generated in co-flow planar solid oxide fuel cells (SOFCs) with porous composite electrodes is predicted using the cell combined micro- macro-model; and the effect of the microstructural variables of the electrodes on the cell power generation is studied. In the combined micro- macro-model, the electrochemical performance of the porous composite electrodes is determined from the micro-model and the distributions of the temperature in solid structure of the cell and the temperature and species partial pressures of the bulk fuel and air streams are determined from the cell macro-model. As a case study, the effect of the microstructural variables of the porous composite electrodes of the Ni-YSZ/YSZ/LSM-YSZ cell operated at the given voltage, fuel utilization ratio, and excess air, on the average power density of the cell is investigated through computer simulation. The results reveal that there is an optimum value for each microstructural variables of the electrodes at which the cell power density is maximized.
Topics: Composite materials, Density, Electricity (Physics), Electrodes, Power density, Solid oxide fuel cells
Effect of Co-Doped GDC Buffer Layer on the Power Density of Solid Oxide Fuel Cell (SOFC)
Jung-Hoon Song, Young-Min Park, Hong-Youl Bae, Jinsoo Ahn, Byeong-Geun Seong, Do-Hyeong Kim, Joong-Hwan Jun
Proc. ASME. FUELCELL2010, ASME 2010 8th International Fuel Cell Science, Engineering and Technology Conference: Volume 1, 319-324, June 14–16, 2010
It is usually accepted that the doped ceria buffer layer is needed between the conventional yttria-stabilized zirconia (YSZ) electrolytes and the Fe and Co containing cathode materials such as (La,Sr)(Co,Fe)O 3-δ (LSCF) to improve the cell performance and to prevent unwanted chemical reactions between them. In this study, the effect of the sintering temperature, cobalt doping amount, and the starting powders of GDC (Gadolinium Doped Ceria) layer were investigated. The cell testing result indicated that it would be desirable to decide the sintering temperature of the GDC layer less than 1250°C to minimize the effect of the solid solutions based on (Zr, Ce)O 2 . Furthermore, 5 days operations of the button cell with cobalt doped GDC layer showed the increased ohmic and polarization resistance, indicating the cobalt segregation from the GDC layer during the long term operation.
Topics: Polishing equipment, Power density, Solid oxide fuel cells, Cobalt, Sintering, Temperature, Chemical reactions, Electrolytes, Gadolinium, Polarization (Electricity)
Metal-Supported SOFC on Compressed Ni-Al Foam Substrates
Alevtina Smirnova, Vladislav Sadykov, Natalia Mezentseva, Vladimir Usoltsev, Oleg Smorygo, Oleg Bobrenok, Nikolai Uvarov
This work presents results of design and characterization of metal-supported SOFC using a new type of metallic substrate made of foam Ni-Al alloy compatible with other cell components. Anode nanocomposites NiO/YSZ with graded grain size and porosity were supported via slip casting. A thin (∼ 10 μm) layer of YSZ was supported by MOCVD. Functionally graded layered cathode LSM/LSM+ScCeSZ was supported by electrostatic spray deposition. For button-size cells a power density up to 500 mW/cm 2 at 700 °C was obtained using wet H 2 -air feeds. Cell performance was stable without degradation at short–term tests (∼100h) at 600–800 °C.
Topics: Metals, Solid oxide fuel cells, Alloys, Anodes, Design, Grain size, Metalorganic chemical vapor deposition, Nanocomposites, Porosity, Power density