bluuebunny/crossref_metadata_2025 huggingface dataset:
Novel Proton Conducting Fullerene Electrolyte
Authors: Pugazhendhi Permual , Loutfy Kevin , Loutfy Raouf , Venkatesan Arun , Tasaki Ken
Published: May 2008

Polymer electrolyte membrane (PEM) fuel cells deliver high power density and have lower weight and volume compared to other fuel cells. However, current fuel cell membrane technology depends on water for proton transport. This restricts the fuel cell operational temperature range and requires the use of a heavy and bulky humidification sub-unit. Recently, MER has developed a novel PEM which circumvents this limitation by incorporating protons bonded to fullerenes. This membrane has a wider operational capability temperature range, significantly increases the performance and reduces dependence on humidification.
Low Pt Thin Cathode Layer Catalyst Layer by Reactive Spray Deposition Technology
Authors: Maric Radenka , Roller Justin M. , Neagu Roberto , Fatih Khalid , Tuck Adam
Published: May 2008

National Research Council Canada's Institute for Fuel Cell Innovation, NRC-IFCI, has been developing the Reactive Spray Deposition Technology (RSDT) process to optimize composite electrode layer formation and develop novel electrocatalysts and catalyst layers. The RSDT process provides the means necessary to develop the next generation of thin, low platinum or alloy catalyst layers for PEM MEA's. In order to best manage water distribution, mass transport and conductivity, the structure should be a gradient with controlled porosity and controlled distribution of both platinum and ionomer across the catalyst layer. The RSDT process allows good control of the platinum particle size as they are created directly from metal vapors, which prevents agglomeration in the catalyst layer. Additionally, it has the flexibility to build a gradient layer structure across a very thin film catalyst layer (<1 um). In our design, a platinum sub-layer (100 nm) was deposited directly on a Nafion® 117 membrane as a columnar structure. After the sub-layer, the platinum loading was reduced in a co-deposited layer of Pt-Nafion (ionomer)-carbon with the lowest loading closest to the GDL. The combined loading of both layers was <0.05mg/cm2 Pt with this approach. The manufactured catalyst layer has a performance of 0.65V at 1 A/cm2 with 0.05mg/cm2 Pt loading using pure oxygen .
Application of Lattice Boltzmann Method to the Simulation of Multiphase Flow in the Inhomogeneous Porous Electrode of a PEM Fuel Cell
Authors: Park Jaewan , Li Xianguo
Published: May 2008

The lattice Boltzmann (LB) method is applied to the multi-phase flow phenomenon in the inhomogeneous gas diffusion layer of a PEM fuel cell. The inhomogeneous porous structure of the carbon cloth and carbon paper has been modeled as void space and porous area using Stokes/Brinkman formulation and void space and impermeable fiber distributions obtained from microscopic image. The permeability of the porous medium is calculated and compared to the experimental measurements in literature showing a good agreement. Simulation results indicate that the permeability of the medium is strongly influenced by the fiber orientations. Present LB flow models are applied to the multi-phase flow simulations by incorporating multi-component model with inter-particle interaction. The model successfully simulates the complicated unsteady behaviors of liquid droplet motion in the porous medium providing a useful tool to investigate the mechanism of liquid water accumulation/removal in a gas diffusion layer of a PEM fuel cell.
Conceptual Design for an Externally Cooled HT-PEMFC Stack
Authors: Scholta Joachim , Zhang Weibo , Jörissen Ludwig , Lehnert Werner
Published: May 2008

One key issue in HT-PEMFC stack development is heat removal at the operating temperature of 140 {degree sign}C to 180 {degree sign}C using e.g. thermooil, steam or pressurized water. In this contribution, cooling designs based on air are described which are avoiding two constraints. First, in the cell active area, no cooling water is present avoiding any sealing problems with respect to the electrode. Secondly, the external positioning allows high temperature gradients between the heat removal zone and the active area resulting in a good adjustability of appropriate reformate conversion temperatures (e.g. 160 {degree sign}C) and a more compact cell design. Different design concepts were investigated using modeling techniques and a selection of them has also been investigated experimentally.
Unique Fuel Cell Test Fixture Allowing Independent Control of Gas Sealing and Electrical Contact Pressure
Authors: Brown Tim M. , Brouwer Jacob , Samuelsen G. S.
Published: May 2008

This paper describes the development of a unique single cell proton exchange membrane (PEM) test fixture to independently investigate the effects of gas sealing and assembly pressure. The test fixture is shown to provide useful insights into the effects of pressure on contact resistance. Two versions of gas diffusion layers (GDL) were tested to demonstrate that contact pressure significantly affects cell performance. In general, performance tends to increase with clamping force until a plateau is reached, after which performance drops rapidly. The rapid drop at high GDL pressure is due to puncture of the membrane or GDL mechanical failure. The performance improvements with pressure may be due to reductions in electrical or ionic resistance.
Cost Reduced Design and Performance Test of the Ejector for a Proton Exchange Membrane Fuel Cell Based on the Sensitivity Analysis
Authors: Kim Minjin , Sohn Young-Jun , Lee Won-Yong
Published: May 2008

Currently, an ejector has been focused as the good fuel recirculation system of the automotive PEMFC. The ejector needs no parasitic power to operate and has very simple structure. The overall efficiency of the PEMFC system using the ejector is enhanced and the system is easy to be operated and maintained. However, the existing commercial ejector does not meet the various operating requirements arising from the fuel cell system. Therefore, it is essential to design the ejector customized to the PEMFC system. In this study, the cost reduced design methodology of the ejector for the automotive PEMFC is proposed based on 1-dimensional model and the sensitivity analysis at critical model operation. The component model based sensitivity analysis is very effective to reduce the time and cost to develop the customized ejector by selecting the important design factors. The selection of the major design factors reduces the redesigns and experimental trials. Consequently, the ejector designed by the proposed methodology has met the desired performance of the ejector for the PEMFC through the whole operating range of the target automotive PEMFC system.
Study on the Steady-state and Dynamic Performance Characteristics of a Polymer Electrolyte Fuel Cell under Various Cathodic Humidification Conditions
Authors: Lee Yongtaek , Kim Bo Sung , Kim Yongchan , Choi Jong Min
Published: May 2008

The dynamic characteristics of a polymer electrolyte fuel cell (PEFC) were investigated for various humidification conditions at steady-state and transient conditions. The PEFC studied in this study was characterized by I-V curves in the potentiostatic mode. The effects of cathodic external humidification for relative humidity of air from 20% to 100% were measured as dry hydrogen was supplied to the anode of the PEFC. In the high voltage region, the performance increased with the increase of the cell temperature, but in the low voltage region, the performance decreased with the increase of the cell temperature. The dynamic responses of the PEFC were also monitored by changing the voltage of the PEFC. As the cell temperature increased, the transient time to steady-state became short. The self-humidification by the water produced delayed the stabilization of the current, except at the low voltage conditions.
Detection of Leakages by Current Density Measurements
Authors: Schulze Mathias
Published: May 2008

In order to increase the reliability of fuel cells an on-line diagnostic method, which allows to detect errors and malfunctions in the operation as well as failures in the fuel cells in an early state is necessary. For this purpose locally resolved current density measurements are an important tool, but the main problem of all on-line analytic tools is the interpretation of the data related to the detection of malfunctions or failures. Therefore, the methodology should be developed by testing fuel cells with defined malfunctions and failures. In this way, an understanding of the on-line analytic measurement results with respect of the errors can be developed. In this paper the results of current density measurements performed in a fuel cell with a leakage is discussed.
Computational Modeling of a Polymer Electrolyte Membrane Fabrication Process
Authors: Harris Tequila , Bhamidipati Kanthi Latha
Published: May 2008

Major issues regarding the commercialization of polymer electrolyte membrane fuel cells (PEMFCs) are cost, reliability and durability. The most common forms of fuel cell failure result from chemical, thermal and mechanical influences, especially with regards to the electrolyte membrane. However, minimal studies exist to understand the manufacturing defects associated with the old and new classes of membranes. In the present work, 2D studies are performed to understand the effect of electrolyte fluid and flow properties, during manufacturing, on the quality of the membrane film. Multiphase CFD models are used for solving the flow behavior of a shear-thinning non-Newtonian fluid. The viscosity and velocities were found to have a profound effect on the membrane structure.
Materials Performance of Modified 430 Stainless Steel in Simulated SOFC Stack Environments for Integrated Gasification Fuel Cell System Applications
Authors: Ziomek-Moroz Malgorzata E. , Adler Thomas , Alman David E. , Jablonski Paul D. , Clark John , Penner Larry
Published: May 2008

The corrosion behaviors of a low silicon and aluminum 430 stainless steel with and without ceria surface treatment were investigated in a simulated coal syngas at 800 {degree sign}C and in air. Thermodynamic calculations were made to predict carbon activities for the coal syngas as a function of temperature. At 800 {degree sign}C, carbon activity is ~1.1, which indicates that carbon that forms could diffuse into the steel and induce carbon corrosion, e.g. carburization and metal dusting. The surface morphology was investigated with X-ray diffraction and scanning electron microscopy. In coal gas, the scale formed on bare steel consisted of Mn1.5Cr1.5O4 and Cr2O3 and on ceria treated steel (Fe, Mn)O, FeCr2O4, Cr2O3, and CeCrO3. Both materials underwent carburization, but not metal dusting. The results of oxidation in air using a thermogravimetric apparatus confirmed that the 430 sample was less resistant to oxidation than the 430 treated with ceria.
Influence of Cathode Porosity on the Characteristics of Medium-Temperature SOFC Single Cells
Authors: Lust Enn , Nurk Gunnar , Kivi Indrek , Küngas Rainer , Möller Priit , Kurig Heisi , Kallip Silvar
Published: May 2008

Meso/macroporous La1 xSrxCoO3 δ, Pr1 xSrxCoO3 δ and Gd1 xSrxCoO3 δ powders with the specific surface area higher than 100 m2 g 1 from the corresponding nitrates have been synthesized using solution decomposition method. These nanopowders have been used for preparation of SOFC cathodes, demonstrating lower oxygen electroreduction activation energy than corresponding less porous cathodes prepared using traditional solid state reaction method. To increase macroporosity of the cathodes the special pore forming agent has been added into the raw cathode paste. The single cells based on the Ce0.9Gd0.1O1.95 electrolyte and Ni-Ce0.9Gd0.1O1.95 cermet anode have been completed and tested using the humidified hydrogen and 10 % (wt) H2 + 90 % Ar mixture. The very low total polarization resistance and activation energy have been obtained. According to IUPAC, the micropores are pores with the diameter d lower than 2 nm, the mesopores are with d from 2 to 20 nm and macropores are with d more than 20 nm.
Electronic Conductivity and Efficiency of SOFC Electrolytes
Authors: Yamaji Katsuhiko , Xiong Yueping , Kishimoto Haruo , Horita Teruhisa , Brito Manuel E. , Yokokawa Harumi
Published: May 2008

Relatively high electronic conductivity of SOFCs' electrolytes significantly decrease the energy conversion efficiency on power generation. This feature was confirmed especially for LSGMC and GDC electrolytes. The effect of electron conductivity on the efficiency for GDC electrolyte was very sensitive to fuel utilization rate. The efficiency increases with fuel utilization rate because the oxygen partial pressure in the fuel increases with fuel utilization rate and the electronic conductivity decreased with increasing the oxygen partial pressure.
Development of Delta-Type High Power Density Solid Oxide Fuel Cells at Siemens Stationary Fuel Cells
Authors: Huang Keqin
Published: May 2008

This paper describes recent development in Siemens Stationary Fuel Cells of Delta-type high power density solid oxide fuel cells, the foundation for future high power and high efficiency electrical power generation. Relatively high-level overviews are given in the areas of cell materials, basic cell design, basic bundle design and basic module design. The testing results of six-cell Delta 9 bundle and single Delta 8 cell are particularly highlighted to demonstrate the unique advantage of high power density and high total power presented by Delta geometry.
Development of Intermediate-temperature SOFC Modules and Systems
Authors: Shibata Makoto , Murakami Naoya , Akbay Taner , Hoshino Koji , Hosoi Kei , Nakajima Hiroaki , Kano Jiro , Nishiwaki Futoshi , Inagaki Toru , Yamasaki Satoru
Published: May 2008

Mitsubishi Materials Corporation and The Kansai Electric Power Co., Inc. have been jointly developing intermediate-temperature solid oxide fuel cells as stationary power generation units since 2001. High performance LSGMC cells and a unique seal-less cell-stack design enable high efficiency operation at temperatures below 800oC. The 1st long-term durability test over 4,200 hours of the 4th generation 1kW-class module was ended in 2006 with a voltage degradation rate of about 0.5%/1000hours. And the 2nd durability test and output fluctuation tests were conducted in 2007. Scaling-up of the module toward 10kW-class has been successfully done and the electrical efficiency of 50% HHV on DC output was achieved in 2006. The first field test of 10kW-class CHP system was performed in 2007.
Investigation of Locally Resolved SOFC with Respect to Flow Configuration and Gas Composition
Authors: Friedrich K. A. , Metzger Patrick , Schiller Günter , Müller-Steinhagen Hans
Published: May 2008

In this contribution the usefulness of spatially resolved measurements for the optimization of operating strategies for SOFC is demonstrated. First the influence of the flow configuration on power density and temperature is discussed. Increasing fuel utilization results in an inhomogeneous gas and current density distribution. The investigation of the locally resolved gas composition is important for the understanding of critical operating conditions, their avoidance and for elucidating degradation effects. It is found that a counter flow configuration has a more homogeneous temperature dependence compared to a co-flow arrangement. With reformate operation carbon deposition may occur at low water levels which might endanger long-term operation.
Power Generation Experiment Of Segmented Planar SOFC
Authors: Iwai Hiroshi , Saito Motohiro , Yoshida Hideo , Kodani Kazufumi , Yoshikata Kuniaki , Ooboshi Takanori
Published: May 2008

A unique planar type solid oxide fuel cell is designed and its performance is experimentally evaluated. In this design, cells are segmented into mini-cells and are connected in series and sandwiched by alumina plates to form a test plate that is the minimal unit of the experiment. Power generation experiment using this minimal unit is conducted varying the operation temperature and the hydrogen concentration in the fuel flow to find its fundamental performance. It is found that the designed test plate shows reasonable power generation characteristics and achieves relatively high output voltage with unit test plate suitable for small applications.
Intermediate-Temperature SOFC Optimized for High Power Density Operation
Authors: Uozumi Gakuji , Eto Hirouki , Akikusa Jun , Chitose Norihisa , Akbay Taner , Hoshino Koji , Hosoi Kei , Inagaki Toru , Yamasaki Satoru
Published: May 2008

Optimization of the electrolyte and the fuel electrode has been performed to increase the output power density of intermediate-temperature solid oxide fuel cells (IT-SOFCs). In order to fabricate novel fuel-electrodes, Gadolinium doped ceria (GDC) powder, which incorporates nano-sized Ru or GDC particles, was developed. The heating rate at sintering of electrolyte was optimized to obtain fine-grained structure for thinner electrolyte by increasing the material strength. For enhanced conversion of methane into hydrogen inside the cell-stack, a fuel-side current collector containing a mixture of nickel and doped ceria (GDC or SDC) with Ru nanoparticles was developed. Maximum output power density of 0.55W/cm2 was obtained with fuel utilization of 75% at 750{degree sign}C.
Small Size Cylindrical Molten Carbonate Fuel Cells and Future Approaches for Decreasing Working Temperature
Authors: Rossi Federico , Nicolini Andrea , Di Profio Pietro
Published: May 2008

The paper deals with the development of an original small size cylindrical molten carbonate fuel cell (SSMCFC) and an investigation for decreasing its working temperature. High benefits are obtained by the proposed configuration in terms of construction time and costs, thermal dispersion minimization, global efficiency; minimization of gases tight problems, compression strain uniformity on the contact surface. A 1kW stack constituted by 15 single cells was tested with good results. However, SSMCFC is characterized by high working temperatures (600-700{degree sign}C). Thus, high temperatures and the typical used electrolyte may accelerate the cell components breakdown and corrosion. An investigation on using ionic liquids as electrolyte support instead of a lithium aluminate porous element was carried out by an experimental facility. Test results allowed to individuate the optimum kind of ionic liquid for SSMCFC matrix support and possible other adjustment for performances improving.
Verification of CFD Modeling for 5kW class MCFC Stack Composed of 7 Unit Cells with 7,500cm2 in Effective Electrode Area
Authors: Kim Seung-Goo , Choi Young-Jae , Jun Joonghwan , Lim Hee-Chun , Lee Jung-Eui
Published: May 2008

A 5kW class MCFC short-stack composed of 7 unit cells was fabricated using the separator with the effective electrode area of 7,500cm2, and the electric performances as well as temperature distributions and pressure differences at various operational conditions were observed. To improve its flatness, the separators were designed employing new concepts such as 3-piece architecture, simple channel structure, and flat mask plate. The current density, air and fuel utilization, and gas pressure were selected as the operational parameters for stack operation. The numerical analysis for the stack using in-house made CFD module for MCFC was also carried out. The temperature distributions, pressure differences, and current density distributions of the unit cells were calculated at various fuel utilizations. To evaluate the effectiveness of the CFD model, finally, the results of the stack operation tests were compared with the prediction of numerical analysis.
Humidity Standard of Compressed Hydrogen for Fuel Cell Technology
Authors: Huang Peter
Published: May 2008

Compressed hydrogen is one of the most important utilities in fuel cell industry. For the specification of hydrogen fuel quality and for the design of humidification equipment, knowledge of the equilibrium water content of hydrogen as a function of temperature and pressure is desirable. A simple presentation in chart form is usually adequate for most fuel cell applications and such a chart has been prepared based on the information on the water vapor content of a hydrogen-water mixture. Absolute humidity of grams of water vapor per kilogram of dry hydrogen is plotted as a function of pressure up to 1000 atmospheric pressures for various dew/frost-point temperatures in the range of -70 {degree sign}C to 90 {degree sign}C. The chart can be used directly to determine the water vapor concentration of compressed hydrogen, the dew/frost- point of such hydrogen-water vapor mixture when pressure is reduced to a lower pressure, usually one atmospheric pressure.
Flexible Co-Production of Renewable Hydrogen and Electricity
Authors: Patel Pinakin , Lipp Ludwig , Jahnke Fred , Tyndall Daniel , Holcomb Franklin
Published: May 2008

Co-production of renewable hydrogen and electricity using high temperature fuel cells offers a potentially attractive option for the hydrogen infrastructure. The multiple co-products help to reduce the cost of delivered hydrogen. Operation of high temperature fuel cell (DFC®) systems on renewable fuels, such as digester gas, has been demonstrated at over a dozen sites. Electrochemical Hydrogen Separation (EHS) systems, currently under development at FCE, can separate the hydrogen produced in the DFC® system with relatively low energy consumption and do not require pressurization. The separation process is virtually emission-free. A sub-scale EHS stack has been operated for more than 9,000 hours. Hydrogen separation efficiencies of up to 90% have been demonstrated. Technology development status and the potential benefits of this co-production system for dual use - civilian as well as military use - are discussed.
Portable Hydrogen Storage Based on New Chemistry of Sodium Borohydride
Authors: Stanic Vesna , Braun James , Pierce Walter , Betts Daniel
Published: May 2008

To overcome the problems of a current hydrogen storage technology, EnerFuel has invented a proprietary chemical process, which produces hydrogen through a new chemical reaction of sodium borohydride. Based on the new chemistry, EnerFuel developed portable hydrogen storage and generator system. This device has 7.03 kWh total hydrogen content and is designed to provide hydrogen on demand for 1W to 60 W fuel cells. However, the simple system design allows for easy scaling up or down hydrogen content and flow rates. This specific storage is designed to be used on board of a remote surveillance system produced by EnerFuel. The storage operates at low pressure and in a wide temperature range from less than 0{degree sign}C to 80{degree sign}C. A new storage is a safe and reliable supply of hydrogen. The hydrogen is generated and present only when required by fuel cell. As a result of the advanced design, the hydrogen volumetric capacity is 40.8 g/L, and gravimetric capacity is 35.2 g/kg.
Desulfurization of Jet A-1 and Heating Oil: General Aspects and Experimental Results
Authors: Peters Ralf , Latz Jochen , Pasel Joachim , Stolten Detlef
Published: May 2008

Different novel technologies have been screened for liquid phase desulfurization, i.e. an extraction with ionic liquids, a fractional distillation, a membrane separation, a selective adsorption and a novel hydro-desulfurization technology (HDS). From lab-scale studies two desulfurization concepts were developed, i.e. a concept for an improved HDS technology and a two-stage concept. Before HDS the liquid fuel is externally saturated with syngas. Related to commercial HDS no gas recycle is necessary. For the second concept a light cut fraction is separated by distillation, while the heavy fraction is led back to the aircraft's tank. The subsequent deep desulfurization is realized by adsorption.
Sorbents For Natural Gas Desulfurization
Authors: Alptekin Gokhan , Jayaraman Ambalavanan , Dubovik Margarita , Schaefer Matthew , Ware Michael , Amalfitano Robert
Published: May 2008

Natural gas is the fuel of choice for fuel cell applications due to its extensive existing supply infrastructure. However, the sulfur level in the natural gas needs to be reduced to less than 0.1 ppm for use in the fuel cells. TDA has developed SulfaTrapTM series of sorbents to effectively remove sulfur by adsorption from natural gas streams and has been carrying out field demonstrations with fuel cell developers for the past two years. In this paper we have compare the performance of the TDA's SulfaTrap sorbents with commercially available adsorbents.
Experimental Evaluation of a Pt-based Heat Exchanger Methanol Reformer for a HTPEM Fuel Cell Stack
Authors: Andreasen So̸ren J. , Kær So̸ren K. , Nielsen Mads P.
Published: May 2008

Fuel cell systems running on pure hydrogen can efficiently produce electricity and heat for various applications, stationary and mobile. Storage volume can be problematic for stationary fuel cell systems with high run-time demands, but it is especially a challenge when dealing with mobile and automotive applications. Using a liquid hydrocarbon as e.g. methanol as the hydrogen carrier and reforming it to a hydrogen rich gas can solve some of these storage issues. The work presented here examines the use of a heat exchanger methanol reformer for use with a HTPEM fuel cell stack. Initial experimental results and conclusions are presented for this reformer.
Final CO Clean-up Step of Reformate Gases via Methanation Process
Authors: Specchia Stefania , Galletti Camilla , Saracco Guido , Specchia Vito
Published: May 2008

Selective CO methanation (CO-SMET) over Ru-based catalysts was investigated as a strategy for complete CO removal in fuel processing applications. The CO-SMET seems to be a good alternative to the CO preferential oxidation (CO-PROX) for the applications on PEM-FCs to transportation vehicles, boats, yachts and residential co-generators, as a CO-SMET reactor is inherently easier to control than the CO-PROX one. The present paper deals with the study of complete removal of CO in H2-rich gas stream through CO-SMET over Ru-based catalysts on TiO2, ZrO2 and CeO2. All the catalysts were prepared by a conventional impregnation method and CO removal was determined by varying the operating conditions. The obtained results showed good performances of Ru-ZrO2 and Ru-CeO2 supported catalysts, and also the feasibility and applicability of the CO-SMET process, especially when the Ru-CeO2 supported catalyst is employed.
Modeling and Implementation of a 1 kW, Air Cooled HTPEM Fuel Cell in a Hybrid Electrical Vehicle
Authors: Andreasen So̸ren J. , Ashworth Leanne , Remόn Ian N. , Rasmussen Peder L. , Nielsen Mads P.
Published: May 2008

This work is a preliminary study of using the PBI-based, HTPEM fuel cell technology in automotive applications. This issue was investigated through computational modeling and an experimental investigation. A hybrid fuel cell system, consisting of a 1 kW stack and lead acid batteries, was implemented in a small electrical vehicle. A dynamic model was developed using Matlab-Simulink to describe the system characteristics, select operating conditions and to size system components. Preheating of the fuel cell stack with electrical resistors was investigated and found to be an unrealistic approach for automotive applications. A simple and reliable approach to temperature management in the stack was using the unpressurized, cathode air stream as coolant.
Remote Surveillance System with Wireless Data Transmission Powered by PEM Fuel Cell
Authors: Ngu Yan , Stanic Vesna , Betts Daniel , Hodge Rex , Saelzer Max , Zabriskie Skip , Fuchs Michael , Pavlik Tom , Pierce Jeff
Published: May 2008

A unique Remote Surveillance System (RSS) that utilizes the latest cellular technology for wireless data transmission is produced. Cameras for night and day vision, wireless module, GPS and power electronics and control devices are powered by a complex hybrid power system. When placed anywhere in the world the system is capable of wireless uninterrupted image transmission at any conditions through web-based user interface. The RSS is able to operate independently for more than a year. The RSS is packed in a back pack and can be carried easily due to low weight and volume. The long operational life without refueling, portability, low cost, and reliability of the RSS are provided by major technological advancements made in Polymer Electrolyte Membrane (PEM) fuel cell, hydrogen storage, power electronics and controls.
Development of a Portable LPG PEM Fuel Cell System
Authors: Kim Ju-Yong , Lee SungChul , Shin WooCheol , Lee YongGul , Kim DongHyun
Published: May 2008

In this paper we've presented a state of the art portable LPG fuel cell power system producing 200W on average. The system utilizes commercial liquefied petroleum gas (LPG) as fuel. In the system, the fuel, LPG and water are fed into the fuel processor through a patent pending gas/water supply system saving 20% of power consumption through the BOP. The reforming system inside has very high power density and can produce hydrogen equivalent to 600We in a volume of less than 4 liters including gas purification system, and can start up within 12 minutes. The system has gone through 1,100 hrs extended operation, and demonstrated stable 200W normal/ 300W peak power outputs. It also showed storability below freezing temperature as low as -20 oC in a freeze and thaw test.
High Performance Direct Ammonia Fueled Solid Oxide Fuel Cells Based on Proton Conducting Solid Electrolytes
Authors: Yoo Yeong , Lim Nguon , Phongaksorn Monrudee , McFarlan Andrew , Maffei Nicola
Published: May 2008

The high performance anode supported single cells for ammonia fueled SOFCs, comprising of BSCF (Ba0.5Sr0.5Co0.8Fe0.2O3-δ)//BCY//NiO-BCY have been fabricated by wet colloidal spray for depositing 10-15 µm thin film electrolytes. The detailed characterization of BSCF, including electrical conductivities of sintered specimen as a function of temperature has been conducted to investigate the possibility to utilize BSCF as cathode for proton conducting electrolyte based cells. The electrochemical performance of single cells was characterized at the temperature 600-700 {degree sign}C under humid 75% H2 in N2 (3% H2O) as well as cracked ammonia as the fuel gas and air as the oxidant gas at a gas flow rate of 10-100 mL min-1. The open circuit voltages were around 1.05-1.08 V at 600 {degree sign}C indicating little gas leakage through the electrolyte. Maximum power density of 250 mW/cm2 was obtained at 600 {degree sign}C under air as the oxidant gas and humid 75% H2 in N2 (3% H2O) as the fuel gas at gas flow rates of 100 and 10 mL min-1, respectively.
Design and Numerical Study for 1kW Tubular SOFC APU System
Authors: Dong Sang-Keun , Yun Byeong-Taek , Lee Dae-Keun
Published: May 2008

In this work, numerical analysis and experiment have been conducted for a unit cell, 6-cell bundle, and 1kW tubular SOFC stack with 20 bundles which manufactured by KIER(Korea Institute of Energy Research). We have designed and constructed 1kW SOFC stack with 20 bundles and devised layout for APU system including reformer, heat exchanger, burner and so on. One bundle is made of 6 unit cells. The obtained numerical data are correlated to experimental results such as the polarization curve and power density, which shows good agreement. The obtainable results can be very useful to guide for system improvements and optimization of a tubular SOFC stack and APU system. In this study, the present model including the electrochemical reactions is implemented in a commercially available CFD software, FLUENT, customization ability via User Define Functions (UDF). Numerical calculations are performed on cluster using a domain decomposition strategy.
Development of Solid Oxide Fuel Cell Power Systems for Underwater Applications
Authors: Ghezel-Ayagh Hossein , Junker Sven T. , Peters Jonathan A. , Miller Timothy F. , Martin Jay D. , Lowe Dave
Published: May 2008

The development of fuel cell based propulsion technologies is an area of great interest for undersea applications. Under an Office of Naval Research (ONR) supported STTR project, FuelCell Energy (FCE), Barber Nichols, Inc. (BNI), and the Applied Research Laboratory (ARL) at Penn State University are working together to develop a hybrid fuel cell system for torpedo propulsion. The current project addresses the development of high power density systems which increase the duration and/or range of operation as compared to existing systems.
Market-ready Stationary 6 kW Generator with Alkaline Fuel Cells
Authors: Mulder Grietus , Coenen Peter , Martens Adwin , Spaepen Jef
Published: May 2008

In stationary applications of fuel cells a lot of attention is paid on the development of systems with a nominal power output of about 5 kW. Most of these fuel cell systems are based on PEM-technology and some systems are based on SOFC-technology. However, alkaline fuel cell technology can also be a very interesting technology for small scale stationary applications, because of the possibility of low cost (low cost materials), high efficiency and working in a broad ambient temperature range (-20 up to 40 {degree sign}C). In the past the vulnerability of alkaline fuel cell technology towards CO2 was a severe disadvantage of the technology, but nowadays this problem has been solved. The Flemish technological institute VITO and the alkaline fuel cell stack manufacturer Intensys teamed together to develop a 6 kWel alkaline fuel cell generator. In this article an overview of the design is given and concepts leading to low cost systems without compromising safety. Finally test results will be presented.
Investigation of Initial SOFC Market in Japan
Authors: Kato Tohru , Kashihara Toshinori , Nozaki Ken , Endo Eiichi , Iimura Yoko
Published: May 2008

Marketability for small SOFC systems in Japan is investigated. Output capacity of 1~100 kW for the SOFC system is considered as an appropriate market entry size to avoid competition with low price Diesel engine generators (DEG) whose capacities are generally more than 100kW. At first, size of a Japanese small co-generation and water heater markets are confirmed to estimate market size and installing price for small SOFCs. Next, advantage of SOFCs for household use is investigated by comparing with conventional small cogenerations and water heaters. Third, possibility of installing SOFCs to convenience stores (CVSs) and small to medium size food manufacturers is investigated considering typical business unit size, heat demand and operating time of these businesses. From the result of this research, the possibility and problems to install SOFCs for household use and such small commercial use are clarified.
Synthesis of Copper Nanostructures by Electrodeposition
Authors: Arzhanova Tatiana A. , Kuryavyi Valery G.
Published: May 2008

Double-pulse potentiostatic technique has been applied to synthesis of copper nanoparticles on glassy carbon from acid copper sulfate solution. Influence of the spatial particle distribution on the particle-size dispersion has been studied using the statistical methods. The analysis of histograms of the distributions of experimental criterion (a ratio of the larger radius to a smaller radius in the nearest neighbor particle pair) on the distances showed that particle-size dispersion is caused by their ordered distribution on the glassy carbon surface. At progressive nucleation and diffusional controlled growth the distances between the nearest neighbor particles, for which experimental criterion deviates from theoretical criterion, obey a geometrical progression with a ratio q=1.41 while at instantaneous nucleation they obey an arithmetical progression with a common difference d=1.3. The derived results showed how particle-size dispersion can be limited and how different copper nanostructures can be synthesized.
Electrodeposition of Sm-Co Permanent Magnets From Aqueous Media
Authors: Wei Jen-Chieh , Schwartz Morton , Nobe Ken
Published: May 2008

Aqueous electrodeposition of Sm-Co thin film magnetic alloys has been investigated with Hull cell and parallel electrodes using DC and pulse current (PC) methods. The basic solution consisted of 1M Sm sulfamate, 0.05M Co sulfate and 0.15M glycine. Most experiments were conducted at either 25oC or 60oC and various current densities (CD). Sufficient Sm deposit content was achieved to produce the SmCo5 (16.7 at % Sm) and Sm2Co17 (10.5 at % Sm) intermetallics by heat treatment. Parallel experiments confirmed the Hull cell results that increased temperatures and CDs increased Sm content of Sm-Co alloy deposits. Magnetic saturation decreased linearly and coercivity decreased nonlinearly with increased Sm content. Crystalline structures changed to non-crystalline with increase in Sm content. Increased Sm content tended to change magnetic properties from anisotropic to isotropic. For PC on parallel electrodes, higher PCD and lower bath temperatures increased Sm deposit content but decreased current efficiency.
ZnS Flms Deposited by the Pulse Plating Technique and Their Characteristics
Authors: Murali K. R. , Vasantha S. , Rajamma K.
Published: May 2008

Zinc sulphide thin films were deposited by the pulse plating technique at a duty cycle of 20 % and different deposition current densities in the range 50- 300 mAcm-2. X-ray diffraction studies indicated the films to be polycrystalline with wurtzite structure. Direct optical band gap in the range of 3.6 - 4.0 eV was obtained for the films deposited at different deposition current densities. AES studies indicated a Zn/S ratio of 1.02 - 1.04. The room temperature resistivity values varied in the range of 3.5 - 17 ohm cm as the deposition current density decreases. Photoluminescence emission peak was observed at 388nm at room temperature for an excitation of 325 nm.
Characterization of ZnSe Thin Films Prepared by Electrodeposition
Authors: Fernandes Valeria C. , Mascaro Lucia H.
Published: May 2008

In this work, results on the preparation and characterization of ZnSe thin films obtained by electrodeposition are presented. Voltammetric curves were recorded in order to characterize the electrochemical behavior of the Zn+2/SeO2 system. Thin films were deposited potentiostatically from an unstirred, deareated aqueous solution onto Pt or ITO glass substrates. The underpotential deposition (UPD) of Se, Zn, as well as the alternate layers of Zn/Se/Zn on polycrystalline Pt electrodes by voltammetry are reported. The deposits morphologies were characterised by FEG and AFM.
Microvessel vascular smooth muscle cells contribute to collagen type I deposition through ERK1/2 MAP kinase, αvβ3-integrin, and TGF-β1 in response to ANG II and high glucose
Authors: Belmadani Souad , Zerfaoui Mourad , Boulares Hamid A. , Palen Desiree I. , Matrougui Khalid
Published: May 2008

This study determines that vascular smooth muscle cell (VSMC) signaling through extracellular signal-regulated kinase (ERK) 1/2-mitogen-activated protein (MAP) kinase, αvβ3-integrin, and transforming growth factor (TGF)-β1 dictates collagen type I network induction in mesenteric resistance arteries (MRA) from Type 1 diabetic (streptozotocin) or hypertensive (HT; ANG II) mice. Isolated MRA were subjected to a pressure-passive-diameter relationship. To delineate cell types and mechanisms, cultured VSMC were prepared from MRA and stimulated with ANG II (100 nM) and high glucose (HG, 22 mM). Pressure-passive-diameter relationship reduction was associated with increased collagen type I deposition in MRA from HT and diabetic mice compared with control. Treatment of HT and diabetic mice with neutralizing TGF-β1 antibody reduced MRA stiffness and collagen type I deposition. Cultured VSMC stimulated with HG or ANG II for 5 min increased ERK1/2-MAP kinase phosphorylation, whereas a 48-h stimulation induced latent TGF-β1, αvβ3-integrin, and collagen type 1 release in the conditioned media. TGF-β1 bioactivity and Smad2 phosphorylation were αvβ3-integrin-dependent, since β3-integrin antibody and αvβ3-integrin inhibitor (SB-223245, 10 μM) significantly prevented TGF-β1 bioactivity and Smad2 phosphorylation. Pretreatment of VSMC with ERK1/2-MAP kinase inhibitor (U-0126, 1 μM) reduced αvβ3-integrin, TGF-β1, and collagen type 1 content. Additionally, αvβ3-integrin antibody, SB-223245, TGF-β1-small-intefering RNA (siRNA), and Smad2-siRNA (40 nM) prevented collagen type I network formation in response to ANG II and HG. Together, these data provide evidence that resistance artery fibrosis in Type 1 diabetes and hypertension is a consequence of abnormal collagen type I release by VSMC and involves ERK1/2, αvβ3-integrin, and TGF-β1 signaling. This pathway could be a potential target for overcoming small artery complications in diabetes and hypertension.
Wnt5a is expressed in murine and human atherosclerotic lesions
Authors: Christman Mark A. , Goetz Douglas J. , Dickerson Eric , McCall Kelly D. , Lewis Christopher J. , Benencia Fabian , Silver Mitchell J. , Kohn Leonard D. , Malgor Ramiro
Published: May 2008

Atherosclerosis is an inflammatory disease involving the accumulation of macrophages in the intima. Wnt5a is a noncanonical member of the Wnt family of secreted glycoproteins. Recently, human macrophages have been shown to express Wnt5a upon stimulation with bacterial pathogens in vitro and in granulomatous lesions in the lung of Mycobacterium tuberculosis-infected patients. Wnt5a expression has also been liked to Toll-like receptor-4 (TLR-4), an innate immune receptor implicated in atherosclerosis. These observations, along with the fact that Wnt5a is involved in cell migration and proliferation, led us to postulate that Wnt5a plays a role in atherosclerosis. To investigate this hypothesis, we characterized Wnt5a expression in murine and human atherosclerotic lesions. Tissue sections derived from the aortic sinus to the aortic arch of apolipoprotein E-deficient mice and sections derived from the carotid arteries of patients undergoing endarterectomy were subjected to immunohistochemical analysis. All samples were found to be positive for Wnt5a with predominant staining in the areas of macrophage accumulation within the intima. In parallel, we probed for the presence of TLR-4 and found coincident TLR-4 and Wnt5a expression. For both the Wnt5a and TLR-4 staining, consecutive tissue sections treated with an isotype- and species-matched Ig served as a negative control and exhibited little, if any, reactivity. Quantitative RT-PCR revealed that Wnt5a mRNA expression in RAW264.7 murine macrophages can be induced by stimulation with LPS, a known ligand for TLR-4. Combined, these findings demonstrate for the first time Wnt5a expression in human and murine atherosclerotic lesions and suggest that cross talk between TLR-4 and Wnt5a is operative in atherosclerosis.
Tone-dependent vascular responses to astrocyte-derived signals
Authors: Blanco Víctor M. , Stern Javier E. , Filosa Jessica A.
Published: May 2008

A growing number of studies support an important contribution of astrocytes to neurovascular coupling, i.e., the phenomenon by which variations in neuronal activity trigger localized changes in blood flow that serve to match the metabolic demands of neurons. However, since both constriction and dilations have been observed in brain parenchymal arterioles upon astrocyte stimulation, the specific influences of these cells on the vasculature remain unclear. Using acute brain slices, we present evidence showing that the specific degree of constriction of rat cortical arterioles (vascular tone) is a key determinant of the magnitude and polarity of the diameter changes elicited by signals associated with neurovascular coupling. Thus elevation of extracellular K+ concentration, stimulation of metabotropic glutamate receptors (mGluR), or 11,12-epoxyeicosatrienoic acid application all elicited vascular responses that were affected by the particular resting arteriolar tone. Interestingly, the data suggest that the extent and/or polarity of the vascular responses are influenced by a delimited set point centered between 30 and 40% tone. In addition, we report that distinct, tone-dependent effects on arteriolar diameter occur upon stimulation of mGluR during inhibition of enzymes of the arachidonic acid pathway [i.e., phospholipase A2, cytochrome P-450 (CYP) ω-hydroxylase, CYP epoxygenase, and cycloxygenase-1]. Our findings may reconcile previous evidence in which direct astrocytic stimulation elicited either vasoconstrictions or vasodilations and also suggest the novel concept that, in addition to participating in functional hyperemia, astrocyte-derived signals play a role in adjusting vascular tone to a range where dilator responses are optimal.
Cardiac phosphatase-deficient 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase increases glycolysis, hypertrophy, and myocyte resistance to hypoxia
Authors: Wang Qianwen , Donthi Rajakumar V. , Wang Jianxun , Lange Alex J. , Watson Lewis J. , Jones Steven P. , Epstein Paul N.
Published: May 2008

During ischemia and heart failure, there is an increase in cardiac glycolysis. To understand if this is beneficial or detrimental to the heart, we chronically elevated glycolysis by cardiac-specific overexpression of phosphatase-deficient 6-phosphofructo-2-kinase/fructose-2,6-bisphosphatase (PFK-2) in transgenic mice. PFK-2 controls the level of fructose-2,6-bisphosphate (Fru-2,6-P2), an important regulator of phosphofructokinase and glycolysis. Transgenic mice had over a threefold elevation in levels of Fru-2,6-P2. Cardiac metabolites upstream of phosphofructokinase were significantly reduced, as would be expected by the activation of phosphofructokinase. In perfused hearts, the transgene caused a significant increase in glycolysis that was less sensitive to inhibition by palmitate. Conversely, oxidation of palmitate was reduced by close to 50%. The elevation in glycolysis made isolated cardiomyocytes highly resistant to contractile inhibition by hypoxia, but in vivo the transgene had no effect on ischemia-reperfusion injury. Transgenic hearts exhibited pathology: the heart weight-to-body weight ratio was increased 17%, cardiomyocyte length was greater, and cardiac fibrosis was increased. However, the transgene did not change insulin sensitivity. These results show that the elevation in glycolysis provides acute benefits against hypoxia, but the chronic increase in glycolysis or reduction in fatty acid oxidation interferes with normal cardiac metabolism, which may be detrimental to the heart.
Challenges in translating plasma proteomics from bench to bedside: update from the NHLBI Clinical Proteomics Programs
Authors: Gerszten Robert E. , Accurso Frank , Bernard Gordon R. , Caprioli Richard M. , Klee Eric W. , Klee George G. , Kullo Iftikhar , Laguna Theresa A. , Roth Frederick P. , Sabatine Marc , Srinivas Pothur , Wang Thomas J. , Ware Lorraine B.
Published: May 2008

The emerging scientific field of proteomics encompasses the identification, characterization, and quantification of the protein content or proteome of whole cells, tissues, or body fluids. The potential for proteomic technologies to identify and quantify novel proteins in the plasma that can function as biomarkers of the presence or severity of clinical disease states holds great promise for clinical use. However, there are many challenges in translating plasma proteomics from bench to bedside, and relatively few plasma biomarkers have successfully transitioned from proteomic discovery to routine clinical use. Key barriers to this translation include the need for “orthogonal” biomarkers (i.e., uncorrelated with existing markers), the complexity of the proteome in biological samples, the presence of high abundance proteins such as albumin in biological samples that hinder detection of low abundance proteins, false positive associations that occur with analysis of high dimensional datasets, and the limited understanding of the effects of growth, development, and age on the normal plasma proteome. Strategies to overcome these challenges are discussed.