Performance of dimethyl ether fuel cells using a Pt‐Ru catalyst

Phenomena are presented whereby the performance of a dimethyl ether fuel cell (DDFC) at 80°C is much lower when a Pt‐Ru catalyst is used on the anode than when a Pt catalyst is used, in contrast to the higher performance achieved using a Pt‐Ru catalyst over a Pt catalyst in direct methanol fuel cells (DMFC). The DDFC performance achieved using a Pt‐Ru catalyst increases with temperature and exceeds that using a Pt catalyst at temperatures over 100 °C. After high‐temperature operation, the performance of DDFC using a Pt‐Ru catalyst at 80 °C is improved. By supplying sufficient steam before operation, the performance of DDFC using a Pt‐Ru catalyst at 80 °C is also found to improve. Before and during operation, more steam is needed for stable operation of the DDFC using a Pt‐Ru catalyst at 80 °C than using a Pt catalyst. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(3): 19–25, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20072     

石墨烯在低温燃料电池阳极中的应用进展

石墨烯是一种碳质新材料,具有独特的电学、热学和力学等性能,在电子、能源和催化领域有广阔应用前景。其较大的理论比表面积、超高的载流子迁移率和较高的热稳定性等性质,使其成为燃料电池催化剂的优良载体材料并受到极大关注。综述了石墨烯负载贵金属催化剂的制备方法,然后阐述了石墨烯作为催化剂载体在低温燃料电池阳极中的应用进展。最后,展望了石墨烯作为低温燃料电池催化剂载体的发展趋势。     

铂基/石墨烯催化剂在燃料电池中的应用

综述了石墨烯负载不同形貌铂(Pt)基催化剂(如球形、核壳结构、空心球、花状和立方体形)的制备及在质子交换膜燃料电池、直接甲醇燃料电池及直接乙醇燃料电池等低温燃料电池中的应用进展,并对相关研究的发展进行展望。     

质子交换膜燃料电池新型抗CO阳极结构

质子交换膜燃料电池(PEMFC)广泛采用重整气为燃料,其存在的主要问题是重整气中含有一定浓度的CO(5×10-5～10-2),CO在Pt表面具有强烈的吸附作用,使电催化剂"中毒".通过对提高质子交换膜燃料电池抗CO问题进行研究,在阳极扩散层流场侧担载催化剂(Pt、PtRu)的方法对电极进行修饰,在注入较少量氧化剂(体积百分比为2%的空气)的条件下使电池抗CO性能显著增强,且可以避免电极局部温度过高及可能带来的安全性问题.     

Development of a maximum‐power‐point‐limiting control system for a direct methanol fuel cell

A new maximum‐power‐point limiting (MPPL) control method for a direct methanol fuel cell (DMFC) was proposed. In regard to achieving MPPL, it was affirmed by experiment that it is possible to control the DMFC by simply ensuring that its voltage does not fall below a certain level regardless of its state. An MPPL control system that accomplishes the DMFC voltage limitation required for MPPL control by using a ‘soft‐start function’ fitted in a ready‐made DC/DC converter was developed. It was confirmed by experimental tests that the circuit board of the developed MPPL control system can perform DMFC voltage limitation control. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

Combined carbon‐dioxide‐capturing high‐performance power generation system using a solid oxide fuel cell operating on pressurized fuel/air

The authors recently proposed a high‐performance combined carbon‐dioxide‐capturing power generation system using a solid oxide fuel cell (SOFC) and a closed‐cycle MHD generator, in which pure oxygen is used as the oxidant. This combined system makes the best use of the advantages of combustion with pure oxygen but fails to prevent the efficiency deterioration caused by high power demand for oxygen production. In the present study, the authors modified this previous system and proposed an improved combined carbon‐dioxide‐capturing power generation system using SOFC/MHD characterized by a higher overall thermal efficiency. In this system, pure oxygen is supplied only to the combustor to reduce the power required for the oxygen production, and pressurized air is used as the oxidant gas in the SOFC. The power saving amounts to about 5% of the thermal input, resulting in a very high total thermal efficiency of 67.53% (HHV) or 74.94% (LHV), which is considered to be the highest possible value of the overall thermal efficiency of carbon‐dioxide‐capturing systems. Advantages of the proposed system suggest that it is advisable to continue further research in this direction. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 149(4): 21–30, 2004; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20010     

Modeling and testing of a 1.2‐kW Nexa fuel cell using bond graph methodology

Confronted by the energy and environmental challenges, fuel cells raise a lot of hope. Fuel cells are expected to be an important power source in the future, and the proton exchange membrane fuel cell (PEMFC) is one of the potential candidates, being highly suitable for certain applications. The electrochemical components, especially a fuel cell, are naturally multidisciplinary components rather well adapted to this approach: chemistry, electrochemistry, thermal and electrical engineering are involved. We propose a PEMFC model using the bond graph method. This model takes into account the different physicochemical phenomena in a fuel cell. The modeling of the activation layer (AL) and gas diffusion layer (GDL) of the cathode side is highlighted. This model is then validated by an experimental work where we have used a 1.2‐kW power PEMFC of the Nexa type from Ballard. The static characteristics of the fuel cell obtained by simulation are in good agreement with those of experiments and also from the literature. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

超低铂担量质子交换膜燃料电池电极

为了降低质子交换膜燃料电池(PEMFC)制作成本,必须降低其电极铂担量。中国科学院大连化学物理研究所燃料电池工程中心制备的电极,铂担量已降到0.08mg/cm2。本文使用循环伏安、扫描电镜、电池评价等方法对这种电极进行了分析、表征,其催化剂利用率可以达到30%,催化层厚度大约为5μm。用这种电极与Nafion112组装的电池,性能可达到750mA/cm2,0.7V     

Performance of a novel dot matrix fuel cell using an inorganic micro‐proton conductor

The power generation properties of a novel dot matrix fuel cell using an inorganic micro‐proton conductor were evaluated in dry gas mixtures of hydrogen and oxygen during room‐temperature operation. The single dot matrix fuel cell was composed of aggregates of micro‐electrolyte dots filling pores arranged in a matrix form on a Teflon or polyimide substrate with Pt/C and Pt catalytic electrodes. Micro‐electrolyte dots were prepared by the sol–gel method using titanium phosphorus oxides as the proton conductive hybrid materials. The open‐circuit voltage of the single cell became higher when using a small dot diameter and achieved a maximum of 500 mV with an electrolyte dot density of 17 dots/cm² in the dry gas mixtures during room‐temperature operation. This value corresponds to about one‐half of the theoretical electromotive force. Moreover, the current density of the single cell increased with the dot diameter such that it grew to 8 mA/cm² at a dot diameter of 500 µm. As a result, dot matrix fuel cells connected in series and parallel were found to achieve the cell performance of high‐energy density such as used by high‐energy microchips. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

一种考虑催化层结构参数的PEMFC气相模型

质子交换膜燃料电池的结构设计对燃料电池车的开发具有重要意义。目前的电池模型通常把催化层简化成一层薄膜,作为边界条件使用,无法分析催化层结构对电池性能的影响。建立了考虑催化层结构参数的一维气相模型,通过有限元法研究电池内部的流场和电场分布。仿真结果和实验符合良好。分析指出扩散层的孔隙率对电池性能影响较大,应高于0.3,催化层的孔隙率对电池性能影响较小。在催化剂载量不变的情况下,催化层厚度应为10~20 mm。     

Development of fuzzy control of a fuel cell generation system using FPGA

Control studies for fuel cells are currently being pursued by re-searchers and the results are reported at an increasing rate[1-2]·Since the fuel cell generation system has lowvoltage and high cur-rent output characteristics,the systemperformanceis very …     

Proposal of a high‐performance solid oxide fuel cell combined power generation system with carbon dioxide recovery

A new fossil‐fuel‐utilized high‐performance combined power generation system with liquefaction recovery of carbon dioxide is proposed. In the system, pure oxygen is used as the oxidant gas to prevent the mixture of nitrogen in the exhaust gas and to make the liquefaction recovery of carbon dioxide possible. Solid oxide fuel cell is selected as the topping cycle. The exhaust fuel gas of the solid oxide fuel cell is afterburned with its exhaust oxidant gas of pure oxygen and the heat of the combustion gas is utilized in the bottoming cycle. Nonequilibrium MHD/noble gas turbine cycle is selected as the bottoming cycle because the temperature of the combustion gas reaches about 2300 K. It is made clear through detailed examination of energy balance that the total thermal efficiency of the system using natural gas (methane) as the fuel reaches 63.24% (HHV) or 70.18% (LHV). This efficiency is very high as for the system with carbon dioxide recovery. The proposed system, therefore, has excellent performance, and further research and development is warranted. © 2003 Wiley Periodicals, Inc. Electr Eng Jpn, 143(4): 12–21, 2003; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.10146     

直接甲醇燃料电池用催化阻醇MEA的制备

针对直接甲醇燃料电池(DMFC)催化剂活性低和甲醇渗透等问题,利用Pd的催化阻醇性能,以油胺表面活性剂为添加剂,还原Pd络合物,合成基于Pd的催化阻醇纳米材料,并涂覆到质子交换膜上,与阴极、阳极构成四合一复合膜电极组件(MEA).与常规三合一MEA相比,复合MEA的质子电导率更高,甲醇渗透率降低了 20％,电池性能得到...     

直接甲醇燃料电池双催化层阴极结构和性能

制备了直接甲醇燃料电池双催化层阴极,双催化层由内催化层Pt黑和外催化层40%Pt/C构成。接触角测试、扫描电镜(SEM)以及能谱(EDX)分析结果表明,在双催化层阴极结构中形成了憎水性、孔结构和催化剂浓度梯度分布。循环伏安测试结果表明双催化层具有较多的电化学活性表面积。该双催化层阴极结构有利于氧气扩散和水的排出,提高了电池性能。     

A method for operation of a residential fuel cell system with super capacitor storage and its application to an energy network

We propose electric double‐layer capacitor storage, which has quick response in the output or input of electricity but has a smaller capacity than normal secondary batteries, by application to a residential fuel cell cogeneration system to reduce spike‐shaped electric power consumption. The method is expected to enhance the system utilization rate and to moderate the burdens on a power grid connected to fuel cells or other distributed generators. A low‐pass filter method was introduced for balancing the power supply and demand, and leveling the power input from the grid. According to simulations performed using practically measured load patterns, the appropriate storage capacity is about 500 Wh for a household, and the fuel cell utilization rate or the grid burden improvement is increased by around 40% in comparison with the case of a system without storage capacity. It has been shown that, in an energy network method of five or more households, the storage capacity can be reduced to approximately 40% with extreme burden improvement of less than 90% of the stand‐alone condition. We have also verified the practical operation and the performance of the method by using an experimental system. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(3): 16–27, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20913     

Improved static and dynamic performances of a two‐cell DC–DC buck converter using a digital dynamic time‐delayed control

Multi‐cell converters have been developed to overcome shortcomings in usual switching devices. The control system in these circuits is twofold: first, to balance voltages of the switches and second to regulate the load current to a desired value. However, with a purely proportional controller, the system presents a static error. With a PI controller the static error is annihilated, but at the expense of shortening the stability region and increasing settling time. In this work, a zero static error dynamic controller for a two‐cell DC–DC buck converter is designed. To achieve zero current error, we propose a generalized scheme of a dynamic controller. Then, using nonlinear analysis and Lyapunov stability theory and bifurcation prediction tools, we prove that zero static error is achieved. The proposed controller outperforms the PI controller in terms of settling time in the presence of saturating effect during the start‐up transients. Numerical simulations in the form of time domain waveforms and bifurcation diagrams from switched circuit‐based model are presented to confirm our theoretical results. Copyright © 2010 John Wiley & Sons, Ltd.     

百瓦级新型金属双极板PEM燃料电池堆研制

研制了采用冲压成型薄型金属双极板的百瓦级质子交换膜(PEM)燃料电池堆。对电池堆进行了不同操作条件下的性能测试研究。实验结果表明,所采用金属双极板材料能够在质子交换膜燃料电池工作环境下长时间稳定运行。     

Numerical simulation of intermediate‐temperature disk type seal‐less SOFC fed with partially reformed methane

Since natural gas containing methane as major component is the most promising fuel for the solid oxide fuel cell (SOFC), development of a numerical simulation code of the intermediate‐temperature disk‐type seal‐less SOFC for methane fuel case is considered to be very useful. In this study, therefore, we develop a new simulation code for the single cell unit of this type of SOFC fed with partially reformed methane as the fuel gas, based on the existing simulation code for pure hydrogen. We calculate the current density versus single cell voltage (i–V ) curves of the single cell unit for various cases with a wide range of the cell temperature and prereformer temperature conditions and compare them with the corresponding experimental results. From the results, we confirm that the numerically obtained i–V curves coincide very well with the corresponding experimental ones in all cases. The variations of the i–V curves, which depend not only on the cell temperature but also on the prereformer temperature, are successfully simulated with a sufficiently high accuracy, indicating the validity of the newly developed simulation code. We also investigate the detailed influence of the cell temperature and prereformer temperature on the cell performance on the basis of the numerically obtained gaseous partial pressure profiles in the fuel channel and Nernst potential profiles in the cell, and clarify the reason why the prereformer temperature has obvious influence on the cell performance when the cell temperature is low, though the cell performance is almost independent of the prereformer temperature when the cell temperature is high. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

On the dispersion of a non‐orthogonal TLM cell

The numerical dispersion of a non‐orthogonal transmission line matrix (TLM) algorithm is for the first time investigated. First of all, the dispersion relation is derived in the most general possible case. Then, the validation is carried out in the analysis of a simple one‐dimensional example. Results show that the theory is in excellent agreement with the numerical simulation. Numerical results concerning various cell shape dispersion characteristics are presented and show some relatively weak numerical dispersion even for rather highly distorted cells. Finally, some indications concerning cell shape selection to minimize the non‐orthogonal TLM cell are proposed. Copyright © 2007 John Wiley & Sons, Ltd.     

A method for designing the power and capacitance of fuel cells and electric double‐layer capacitors of hybrid railway vehicles

A hybrid railway traction system with fuel cells (FC) and electric double‐layer capacitors (EDLC) is discussed in this paper. This system can save FC costs and absorb regenerative energy. A method for designing FC and EDLC on the basis of the output power and capacitance, respectively, has not been reported, although their design is one of the most important technical issues encountered in the design of hybrid railway vehicles. Such a design method is presented along with a train load pro?le and an energy management strategy. The design results obtained using the proposed method are veri?ed by performing numerical simulations for a running train. These results reveal that the proposed method for designing the EDLC and FC on the basis of the capacitance and power, respectively, and using a method for controlling the EDLC voltage, is su?ciently e?ective in designing e?cient EDLC and FC of hybrid railway traction systems. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(3): 47–54, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22395