Low temperature fuel cells

Fuel cells have emerged from the research laboratories and are now in the state of being actively developed for various military and commercial purposes. The paper tries to describe the principal problems which had to be overcome to build reliably operating, relatively inexpensive cells. The different systems presently used are compared with each other and the possibility of the use of cheap hydrocarbon fuels in low temperature cells is discussed.     

Fuel cells and fuel batteries?an engineering view

If fuel cells and fuel batteries attain their expected usefulness in the future, electrical and electronics engineers may some day be joined by a new kind of engineer?the electrochemical engineer. The fuel-cell problems this new engineer will have to face include those involving various types of fuels and their properties, efficiency, reliability, life, and operating temperatures. All of these properties are tied in with the important consideration of economics.     

Electrode kinetics and fuel cells

This paper is a presentation of some of those aspects of electrode kinetics which would be of use to scientists and engineers working on fuel cells. It is intended as an introduction to the relevant theory of electrode kinetics. It does not give details of testing circuitry, nor does it review papers on electrode kinetics or fuel cell investigations. A brief mention is made of the application of the basic concepts to porous electrode structures.     

燃料电池技术市场发展前景

笔记本电脑用户都深有感受,仅是供电的锂离子蓄电池(LIB)的重量就高达几公斤之多。笔记本电脑等便携式电子设备的设计者更是苦恼万分,微处理器的功耗每10年增长100倍,而LIB的容量大约每10年仅提高2倍左右,如何解决? Intel公司的IGHz时钟频率的PentiumⅢ微处理器的功耗已高达36W,而现代18650型(直径18mm、高65mm、重量为45g)的LIB,仅有7.4Wh的容量。富士通公司的实验数据表明,一台普通的笔记本电脑平均功耗为50W;若让它工作10小时,需要500Wh的电力;以上述的LIB供电,不得不用68块LIB的电     

Cool fuel

This publication contains reprint articles for which IEEE does not hold copyright. You may purchase this article from the Ask*IEEE Document Delivery Service at http://www.ieee.org/services/askieee/     

新型技术有望造就体积更小、重量更轻的燃料电池

由能源系统开发商CMR Fuel Cells公司(位于英国剑桥)推出的小型混合反应剂(compact mixed-reactant，CMR)技术采用了混合反应剂和流经多孔电池结构的液体，旨在大幅度地降低对燃料电池的材料要求，有望使现用电池的体积和重量实现高达90％的降幅，而且价格也更加便宜。这种更轻、更便宜的燃料电池将造就无须安装电池的便携式电子设备，而且几乎(或根本)不会对封装和成本产生任何不利的影响。     

电池、燃料电池、UPS产品厂商信息

~~电池、燃料电池、UPS产品厂商信息     

促进超级电容器和燃料电池发展的先进聚合物

美国MDElkton的先进材料制造商W.L.Gore公司开发出了一种新的聚四氟乙烯(polytetrafluoroethylene简称PTFE)薄膜，他们宣称该材料可以增加能量密度和在超级电容器与燃料电池中的功率释放。超级电容器也就是人们称之为的电化学双层电容器（electrochemicaldouble-layercapacitors简称ELDCs），它通过离子吸附作用和在电极的界面处及电解液中的去吸附作用，进行能量的存贮和释放。与传统的电池相比较，ELDC通过电化学反应能够快速的进行充电和放电，所具有的能效高达95%以上，这远远超过了从电池中可以获得的能量。W.L.Gore公司推出…     

High-frequency link inverter for fuel cells based on multiple-carrier PWM

Fuel-cell inverter applications typically have a relatively low voltage input, and require a battery bus for energy buffering. Circuit topology issues are examined based on these needs. The need for high step-up ratios, current control, low ripple, and battery storage leads to a current-sourced link converter as perhaps the best choice of conversion topology. High-frequency ac link conversion offers a possible way to reduce the number of power stages, in the form of a cycloconverter, known from previous work. It is shown that the control complexity in this converter can be addressed by adapting pulse-width modulation (PWM) techniques. Here, a multicarrier PWM approach is introduced as a convenient way to implement a high-frequency link inverter. The approach is a direct extension of conventional PWM, and supports square-wave cycloconversion methods that have appeared in prior literature. Simulation and experimental results are developed for a low-voltage ac link inverter, leading to a 48-V fuel cell input design.     

Catalytic properties of composite amorphous carbon-platinum layers in fuel cells

Catalytic properties of composite amorphous carbon-platinum layers produced by magnetron cosputtering have been studied. The layers were characterized by electron microscopy, IR spectroscopy, ellipsometry, gravimetry, and spectrophotometric chemical analysis. The catalytic activity of the layers was studied in an air-hydrogen fuel cell by measuring its load and power characteristics.     

A new power converter for fuel cells with high system efficiency

This paper presents a new high-efficiency grid-connected single-phase converter for fuel cells. It consists of a two-stage power conversion topology. Since the fuel cell operates with a low voltage in a wide voltage range (25?V–45?V) this voltage must be transformed to around 350–400?V in order to be able to invert this dc power into ac power to the grid. The proposed converter consists of an isolated dc–dc converter cascaded with a single-phase H-bridge inverter. The dc–dc converter is a current-fed push-pull converter. The inverter is controlled as a standard single-phase power factor controller with resistor emulation at the output. Experimental results of converter efficiency, grid performance and fuel cell dynamic response are shown for a 1?kW prototype. The proposed converter exhibits a high efficiency in a wide power range (higher than 92%) and the inverter operates with a near-unity power factor and a low current THD.     

Mighty mites [fuel cell power supplies]

In this article, the author examines how the fuel cell's first big market success may be alcohol-fed units small enough to power cellphones, laptops, and PDAs.     

Gas supply control and experimental validation for polymer electrolyte membrane fuel cells

Gas supply system control, which consists of air and hydrogen supply control, are two basic and crucial topics for proton exchange membrane fuel cell (PEMFC) control. To protect the PEM and improve the performance of the PEMFCs, the air pressure and flow of the cathode, and the hydrogen pressure of the anode should be precisely controlled. In this paper, we primarily research the modelling of the cathode and anode and the nonlinear controller design for pressure control, as well as air flow control. In detail, control-oriented models are established for cathode and anode controller design. Owing to the existence of model uncertainty and disturbances, such as humidity, temperature, and water vapour, an extended state observer (ESO) is designed to estimate and compensate for these influences. Cathode and anode pressure controls are synthesized in the uniform control scheme. For air flow control, a feedforward channel based on the air flow model of the compressor and a feedback channel based on the proportional–integral (PI) controller are proposed to regulate air flow. The proposed control methods are validated by experiments under different operating conditions of PEMFCs.     

Hydrocarbon?air fuel cell systems

The fuel cell is basically an energy-conversion device in which chemical energy is isothermally converted into dc electricity. Several types of fuel cell systems have been developed, including the hydrogen-oxygen system used in certain space missions, but many of them employ fuels that are expensive and not readily available. Considerable research and development work is being done on hydrocarbon-air systems, which use air and ``real-world' fuels. In the direct-oxidation cells, the hydrocarbon fuel is oxidized directly at the fuel electrode. Because of reaction problems at the electrode, these cells are still in their early stages of development. In the indirect-oxidation cells, now in the systems engineering development stage, the hydrocarbon fuel is converted into an impure hydrogen, which may then be purified to a certain degree and injected into the fuel cell modules. Initial applications will probably be in the military, because of the fuel flexibility and ease of maintenance inherent in these fuel cell systems.