Review of fuel processing catalysts for hydrogen production in PEM fuel cell systems

The rapid development in recent years of the proton-exchange membrane (PEM) fuel cell technology has stimulated research in all areas of fuel processor catalysts for hydrogen generation. The principal aim is to develop more active catalytic systems that allow for the reduction in size and increase the efficiency of fuel processors. The overall selectivity in generating a low CO content hydrogen stream as needed by the PEM fuel cell catalyst is dependent on the efficiency of the catalysts in each segment of the fuel processor. This article reviews the advances achieved during the past few years in the development of catalytic materials for hydrogen generation through fuel reforming,¹ water-gas shift and carbon monoxide preferential oxidation, as used or aimed to be of use in fuel processing for PEM fuel cell systems.     

Sensitivity analysis of potential fuel savings by implementation of fuel economy standards for motorcycle

Due to the decrease in the total petroleum reserves worldwide, and the growing increase in the price of petroleum, fuel consumption has become the dominant factor in the selection of the proper vehicle. However, in some countries such as Malaysia, people tend to use fuel-efficient vehicles such as motorcycles. Statistics shows that in Malaysia, the number of motorcycles is almost half of the total registered vehicles. Therefore, motorcycles as widely used vehicles have an impact on overall energy consumptions in the country. Minimum fuel economy standard can be one of the effective policies to reduce the fuel consumption in transport sector. While the main problem to set the minimum fuel economy standard is to identify the annual fuel economy improvement of the vehicle, this study aims to find a method to calculate the annual fuel economy improvement and to calculate the potential reduction in fuel consumption by implementing a fuel economy standard for motorcycles in Malaysia. The calculation is based on four scenarios of sensitivity analysis which are 5, 10, 15, and 20 % from the baseline fuel economy. While this study only covers the fuel economy standard of motorcycles, the method can be applied to the other types of motor vehicles without major modifications.     

Materials for fuel cells

Because of their potential to reduce the environmental impact and geopolitical consequences of the use of fossil fuels, fuel cells have emerged as tantalizing alternatives to combustion engines. Like a combustion engine, a fuel cell uses some sort of chemical fuel as its energy source but, like a battery, the chemical energy is directly converted to electrical energy, without an often messy and relatively inefficient combustion step. In addition to high efficiency and low emissions, fuel cells are attractive for their modular and distributed nature, and zero noise pollution. They will also play an essential role in any future hydrogen fuel economy.     

乏燃料贮存格架在组件跌落事故中的冲击分析

为解决乏燃料贮存格架在组件跌落事故中的冲击分析问题,对ANSYSLS-DYNA程序在弹塑性条件下的冲击分析功能进行开发,并运用于300 MW压水堆核电厂乏燃料贮存格架受乏燃料组件撞击的仿真分析中,采用应变失效和变形失效的方法对乏燃料贮存格架进行安全评定,证明现有的设计满足安全要求。所应用的弹塑性冲击分析方法,以及对乏燃料贮存格架评定的方法同样适用于其它核电设备。     

汽车节油迫在眉睫

石油是关系到国家安全的重要战略资源,中国是石油资源相对缺乏的国家,节约用油、提高资源利用效率尤为重要。指出了现阶段我国汽车用油存在的问题;分析了汽车节油技术发展趋势和政策措施;提出通过政策措施倡导节约优先、效率为本的观念,重点开发和应用各种节油技术,提高油品质量,加快淘汰老旧车型,积极开发替代资源,大力发展公共交通和现代物流是现阶段我国汽车节油减排的有效途径。     

Potential fuel savings and emissions reduction from fuel economy standards implementation for motor-vehicles

Currently, the transportation sector alone consumes more than 40% of the total energy consumption in Malaysia. Developed countries around the world have implemented a fuel economy standard for motor-vehicles. This paper attempts to predict the amount of fuel savings and the subsequent economic and environmental impact in the transportation sector by implementing a minimum fuel economy standard for personal vehicles in Malaysia. The calculations are based on the growth of vehicle ownership data in Malaysia. The ownership of private vehicles in Malaysia has rapidly risen from 2,553,574 in 1995 to 6,941,996 in 2006. By implementing the program in 2010 about 15 Gl of fuel can be saved by the end of the year 2018. This correlates to about RM42 billion (1US$ = RM 3.5) in bill savings and 36 million tones of carbon dioxide reductions. This study finds that implementing fuel economy standard for motor-vehicles in Malaysia will provide significant amount of fuel and emission reductions.     

The promise of fuel cell-based automobiles

Fuel cell-based automobiles have gained attention in the last few years due to growing public concern about urban air pollution and consequent environmental problems. From an analysis of the power and energy requirements of a modern car, it is estimated that a base sustainable power ofca. 50 kW supplemented with short bursts up to 80 kW will suffice in most driving requirements. The energy demand depends greatly on driving characteristics but under normal usage is expected to be 200 Wh/km. The advantages and disadvantages of candidate fuel-cell systems and various fuels are considered together with the issue of whether the fuel should be converted directly in the fuel cell or should be reformed to hydrogen onboard the vehicle. For fuel cell vehicles to compete successfully with conventional internal-combustion engine vehicles, it appears that direct conversion fuel cells using probably hydrogen, but possibly methanol, are the only realistic contenders for road transportation applications. Among the available fuel cell technologies, polymer-electrolyte fuel cells directly fueled with hydrogen appear to be the best option for powering fuel cell vehicles as there is every prospect that these will exceed the performance of the internal-combustion engine vehicles but for their first cost. A target cost of $ 50/kW would be mandatory to make polymer-electrolyte fuel cells competitive with the internal combustion engines and can only be achieved with design changes that would substantially reduce the quantity of materials used. At present, prominent car manufacturers are deploying important research and development efforts to develop fuel cell vehicles and are projecting to start production by 2005.     

In situ studies of fuel oxidation in solid oxide fuel cells

Existing electrochemical experiments and models of fuel oxidation postulate about the importance of different oxidation pathways and relative fuel conversion efficiencies, but specific information is often lacking. Experiments described below present the first direct, in situ measurements of relevant chemical species formed on solid oxide fuel cell (SOFC) cermet anodes operating with both butane and CO fuel feeds. Raman spectroscopy is used to acquire vibrational spectra from SOFC anodes at 715 degrees C during operation. Both C4H10 and CO form graphitic intermediates. In the limit of a large oxide flux, excess butane forms ordered graphite but only transiently. At higher cell potentials (e.g., less current being drawn) ordered and disordered graphite form on the Ni cermet anode following exposure to butane, and under open circuit voltage (OCV) conditions the graphite persists indefinitely. The chemistry of CO oxidation is such that ordered graphite and a Ni-COO intermediate form only at intermediate cell potentials. Concurrent voltammetry studies show that the formation of graphite with butane at OCV leads first to decreased cell performance after exposure to 25 cm3 butane, then recovered performance after 75 cm3. CO voltammetry data show that at lower potentials the oxide flux through the YSZ electrolyte is sufficient to oxidize the Ni in the anode especially near the interface with the electrolyte.     

Introduction to fuel cells and hydrogen technology

Whereas the 19th century was the century of the steam engine and the 20th century was the century of the internal combustion engine, it is likely that the 21st century will be the century of the fuel cell. Full cells are now on the verge of being introduced commercially, revolutionising the way we presently produce power. Fuel cells can use hydrogen as a fuel, offering the prospect of supplying the world with clean, sustainable electrical power. The article discusses the history of fuel cells, fuel cells for NASA, alkaline fuel cells for terrestrial applications and PEM fuel cells. Fuel cell applications in transportation, distributed power generation, residential and portable power are discussed. The science of the PEM fuel cell and the direct methanol fuel cell are discussed. Benefits of fuel cells and obstacles to their widespread introduction are briefly outlined.     

An on-vehicle fuel driveability index sensor

The driveability of a vehicle is important to both drivers and vehicle manufacturers. Good driveability can provide drivers with a better driving experience and can result in lower vehicle emissions. The driveability is closely related to the volatility of the fuel used, which is characterized by the driveability index (DI). A sensor of fuel DI has been fabricated and tested on a vehicle. One version is a metal sensor which has an interdigitated cube structure. The sensor element is located in the vapor dome of the fuel tank and is bathed in fuel while the fuel pump is on. After the pump is turned off, a reproducible volume of fuel is retained between the capacitor plates in the sensor element. The sensor element heats the fuel sample, causing it to evaporate while the temperature and remaining liquid volume are monitored. Fuels with different volatility yield differing evaporation rates. By monitoring the fuel level rate of decline as a function of its temperature, a characteristic curve related to the fuel volatility is measured. Six nonoxygenated fuels were used to test the sensor concept. It was found that there was a good correlation between the sensor result and the fuel DI.     

Template synthesis of arrays of nano fuel cells

A method for the construction of an array of fuel cells wherein each cell is 200 nm in diameter is presented. Electrodeposition of Pt-Cu nanowires inside the cylindrical pores of an Anodisc filter membrane and the subsequent dealloying of the Cu by soaking the filter in fuming nitric acid for several hours are used to construct an array of porous platinum electrodes. About 10(9) electrically isolated cylindrical porous electrodes, each 200 nm in diameter, are formed in this manner. Utilizing two arrays of porous electrodes with a polymer electrolyte membrane or an electrolyte support matrix sandwiched between, an array of nano fuel cells is produced. This method of producing an array of coplanar fuel cells allows for the series connection of fuel cells outside the array and eliminates the need for fuel and air manifolds, greatly reducing the overall system complexity. Initial prototypes utilizing an aqueous solution of NaBH(4) as a fuel have produced power densities of ca. 1 mW/cm(2) based on an estimate of the area of the current collectors in contact with the nano-fuel-cell array and have demonstrated the ability to wire bundles of fuel cells either in parallel or in series.     

Engineering porous materials for fuel cell applications

Porous materials play an important role in fuel cell engineering. For example, they are used to support delicate electrolyte membranes, where mechanical integrity and effective diffusivity to fuel gases is critical; they are used as gas diffusion layers, where electronic conductivity and permeability to both gas and water is critical; and they are used to construct fuel cell electrodes, where an optimum combination of ionic conductivity, electronic conductivity, porosity and catalyst distribution is critical. The paper will discuss these characteristics, and introduce the materials and processing methods used to engineer porous materials within two of the leading fuel cell variants, the solid oxide fuel cell and the polymer electrolyte membrane fuel cell.     

Use of tire derived fuel in clinker burning

The prerequisites for using of tire derived fuel (TDF) as a supplement fuel for the clinker production are stated. Measurements were carried out by using different qualitative analytical techniques such as, X-ray diffraction (XRD), X-ray fluorescence (XRF), optical microscopy in two series of raw mill, clinker and fuel samples with and without the use of TDF. Furthermore, the compressive strength of CEM I-52.5 cement produced was measured. In this specific study 6% of the total fuel used was TDF. It was concluded that no apparent problems occurred from the use of TDF as a supplemental fuel in the clinker burning.     

Optimization of microfluidic fuel cells using transport principles

Microfluidic fuel cells exploit the lack of convective mixing at low Reynolds number to eliminate the need for a physical membrane to separate the fuel from the oxidant. Slow transport of reactants in combination with high catalytic surface-to-volume ratios often inhibit the efficiency of a microfluidic fuel cell. The performance of microfluidic devices that rely on surface electrochemical reactions is controlled by the interplay between reaction kinetics and the rate of mass transfer to the reactive surfaces. This paper presents theoretical and experimental work to describe the role of flow rate, microchannel geometry, and location of electrodes within a microfluidic fuel cell on its performance. A transport model, based on the convective-diffusive flux of reactants, is developed that describes the optimal conditions for maximizing both the average current density and the percentage of fuel utilized. The results show that the performance can be improved when the design of the device includes electrodes smaller than a critical length. The results of this study advance current approaches to the design of microfluidic fuel cells and other electrochemically-coupled microfluidic devices.     

质子交换膜在燃料电池中的应用

质子交换膜（ＰＥＭ）燃料电池以质子交换膜为电解质，燃料电池的性能强烈地依赖于质子交换膜的特性。本文综述ＰＥＭ电池对质子交换膜的技术要求及该膜的检测和在燃料电池中的应用情况。     

燃料电池及其材料的发展

综述了燃料电池及其材料的发展概况,着重评述了固体电解质燃料电池的发展情况和它所用的材料。如果固体电解质燃料电池达到实用化,将需要大量的氧化锆、氧化钇和氧化镧等材料。     

Material issues for fuel cell applications

Abstract

Since the successful demonstration of alkaline fuel cell technology by Bacon in the 1950s fuel cells – in one guise or another – have held forth the promise of mass market commercialisation. To date this promise has yet to materialise despite the fact that many products are currently undergoing field evaluation and testing. The primary barrier that fuel cell technology must overcome relates to cost but at its heart this is a materials issue. The problems relate to electrolyte and catalyst performance and cost, chemical stability of the cell interconnect and the long-term reliability of fuel and oxidant seals. In this paper, the detailed issues facing the different types of fuel cells will be summarised and an indepth case study on Solid Oxide Fuel Cells (SOFC) will be presented.     

Hot-bed of fuel cell R&D

Late in 2001, the University of Connecticut unveiled a center of excellence devoted to fuel cell science and technology, the Connecticut Global Fuel Cell Center (CGFCC). The product of a unique collaboration between the State of Connecticut, local industry, and the University of Connecticut’s School of Engineering, the Center supports cutting-edge research, design and commercial development, education, and transfer of fuel cell technology. Though nestled near the University’s main campus in pastoral Storrs, the CGFCC is no rustic, sleepy laboratory. The Center is rapidly emerging as a recognized hub, gaining research momentum in the red-hot fuel cell arena. Analysts project the US fuel cell market will climb dramatically in coming years, $10-50 billion by 2010, with the greatest growth potential in the portable/mobile markets. The industry received a strong boost early in 2002 when President Bush voiced his budget support for integration of hydrogen fuel cells in the US auto industry.Anticipating the approaching trend, the University of Connecticut’s School of Engineering began negotiating in 2000 with Connecticut companies and government/private sector venture capitalists to establish a state-of-the-art center devoted to fuel cell science and technology. The Center was born in December 2001 as a partnership between the School of Engineering, the Connecticut Clean Energy Fund (the state’s renewable energy investment fund), and local industry.     

燃料电池全氟磺酸质子交换膜研究进展

全氟磺酸质子交换膜作为质子交换膜燃料电池和直接甲醇燃料电池的关键部件得到广泛关注.介绍了国内外全氟磺酸质子交换膜的发展历程和现状,讨论了商业化全氟磺酸膜存在的高温质子传导率低和燃料渗透率高等问题.最后结合我们的研究工作综述了解决这些问题的方法和研究进展.     

Modeling: driving fuel cells

You are walking along a busy traffic-filled street and the cars are passing by as they always have done. However, all does not seem right. The air that you are breathing is not filled with the bitter choking smell of exhaust fumes. There is no engine noise coming from the vehicles. How can this be? The answer is that the vehicles are all powered by fuel cells. Once confined to the realms of science fiction, the full commercialization of fuel cells could be just around the corner. Computational chemistry techniques, in particular molecular modeling and simulation, are being used to understand and refine the science driving this quiet, green revolution.Fuel cells were invented in 1839 by Sir William Grove, a Welsh judge and gentleman scientist, as a result of his experiments on the electrolysis of water. To put it simply, fuel cells are electrochemical devices that take hydrogen gas from fuel, combine it with oxygen from the air, and generate electricity and heat, with water as the only by-product.