Fuel cells

The advent of fuel cells for the generation of electricity for portable, small and large-scale stationary and automotive purposes portends radical changes in electricity supply over coming decades. The five main types of fuel cell technology are reviewed (alkaline fuel cell, solid polymer fuel cell, phosphoric acid fuel cell, molten-carbonate fuel cell, and solid-oxide fuel cell) along with their characteristics and electrochemical reactions plus those of a nonhydrogen based regenerative fuel cell for large-scale power delivery     

The performance analysis and design optimization of fuel temperature control for the injection combustion engine

The purpose of the paper is to analyze the performance and design optimization of fuel temperature control in the injection combustion engine. There is a fuel temperature control device designed between the injection and fuel pump to cool down or warm up the fuel. Thermoelectric module (TEC) chips are applied in the device to absorb or dissipate heat from the fuel. There are several results relating exhaust emission and engine output performance to fuel temperature in this paper to display the optimization of fuel temperature for the injection engine. The experimental results indicate that increasing fuel temperature will result in an increase in CO, HC, and in a decrease in NO_x. Increasing the fuel temperature may affect the fuel consumption and engine output for a gasoline engine at different A/F (air to fuel) ratios. With enhanced understanding and analyses, the effects of fuel temperature on engine performance, fuel consumption and emissions can be taken into account in engine design and evaluation.     

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.     

放射性燃油密度测量技术的应用

利用γ射线的指数衰减规律，研制放射性的燃油密度传感器，在不同的环境条件下测量燃油密度。本文主要从放射性燃油密度测量传感器的工作原理，数学建模，测量数据分析等方面来论述放射性燃油密度测量技术在飞机燃油系统中的应用。     

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.     

Mathematical modeling and distribution characteristics evaluation of fuel particles in iron ore sintering process

The distribution characteristics of fuel particles is a key factor affecting the thermal state of sintering. To find out the fuel distribution under different granulation conditions, a mathematical method based on the particle population balance and Lister’s model was established in this study. In combination with experiments including granulation and the fixed carbon and sulfur content of detection, the relative error of this model is within ±1.5. The proportion and particle size composition of fuel are selected to evaluate quantitatively the distribution characteristics. The result shows that the fuel distribution in granules mostly accumulates in the middle size granules. The increase of proportion and fine particles content of the fuel leads to the decline of the fuel content in +5 mm granules. With a higher ratio and higher content of fine particles in the fuel, the fuel distribution in the upper and middle of the sintering beds rises while that of the bottom layer is down, which is conducive to changing the nonuniform distribution of thermal. The fuel particle size composition has greater impact on fuel distribution than its proportion. To better investigation, further parameter simulation and optimization of granulation is necessary.     

有姿态角时飞机燃油油量测量技术研究

本文论述了数字式飞机燃油油量测量系统中的一种全新计算方法——“细分—逼近”法的原理和计算过程。该方法借鉴了有限元法的思想,可计算出形状不规则的飞机油箱在任意时刻、任意姿态角组合时的油量。计算程序中采用了符合组合方法,判断油平面与油箱相截的情况。     

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.     

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.     

圆台形FAE装置抛撒初期燃料运动特性研究

为研究圆台形燃料空气炸药（FAE）装置燃料抛撒运动特性，利用ANSYS/LS DYNA软件对燃料初始抛撒过程进行了数值模拟，得到了不同位置处的燃料抛撒初速，分析了中心抛撒药结构对燃料抛撒的影响，并进行了实验验证。结果表明:圆台形FAE装置不同位置处的燃料抛撒初速与截面比药量有关，燃料抛撒初速随截面比药量的增加而增加；相较于等直径中心抛撒药，采用变直径中心抛撒药时截面比药量一致性更好，有利于减小不同位置处燃料抛撒的速度差。     

数控机床电机-斜齿轮齿条耦合进给系统动态特性分析#br#

数控机床进给系统动态误差是影响加工精度的一个重要因素。针对大型镜像铣床斜齿轮齿条进给系统,通过势能法和切片积分法获得时变啮合刚度,同时考虑啮合误差引入的内部激励建立斜齿轮齿条动力学模型。针对矢量控制电机,建立交流同步伺服电机的双闭环控制动力学模型。将电机模型与齿轮齿条动力学串联构成机电耦合系统动力学模型,通过Simulink 仿真和实验研究,分析啮合误差、电机动态特性对于进给系统动态传递误差的影响,明确了齿轮齿条误差是进给系统的主要误差源。研究成果可为高动态精度的进给系统设计提供参考。     

Transcritical phenomena of autoignited fuel droplet at high pressures under microgravity

An experimental study has been performed under microgravity to obtain the detailed information needed for the deep understanding of the combustion phenomena of single fuel droplets which autoignite in supercritical gaseous environment. The microgravity environments both in a capsule of a drop shaft and during the parabolic flight of an aircraft were utilized for the experiments. An octadecanol droplet suspended at the tip of a fine quartz fiber in the cold section of the high-pressure combustion chamber was transferred quickly to be subjected to a hot gaseous medium in an electric furnace, this followed by autoignition and combustion of the fuel droplet in supercritical gaseous environment. High-pressure gaseous mixture of oxygen and nitrogen was used as the ambient gas. Temporal variation of temperature of the fuel droplet in supercritical gaseous environment was examined using an embedded fine thermocouple. Sequential backlighted images of the autoignited fuel droplet or the lump of fuel were acquired in supercritical gaseous environment with reduced oxygen concentration. The observed pressure dependence of the ignition delay and that of the burning time of the droplet with the embedded thermocouple were consistent with the previous results. Simultaneous imaging with thermometry showed that the appearance of the fuel changed remarkably at measured fuel temperatures around the critical temperature of the pure fuel. The interface temperature of the fuel rose well beyond the critical temperature of the pure fuel in supercritical gaseous environment. The fuel was gasified long before the end of combustion in supercritical gaseous environment. The proportion of the gasification time to the burning time decreased monotonically with increasing the ambient pressure.     

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。     

Application of X-Ray CT for Non-destructive Characterization of Graphite Fuel-Tube

Non-destructive characterization of fuel tube of compact high temperature reactor was carried out using quantitative X-ray computed tomography (CT). The fuel tube is made of graphite and parameters of its fuel/coolant channels such as area, inter-spacing and longitudinal uniformity need to be characterized properly throughout its length to ensure homogeneous temperature distribution. A prototype fuel tube was fabricated and characterized using X-ray-CT at two different resolution scales followed by quantitative image analysis. The study reveals potential of X-ray CT in detecting small scale and large scale uniformity of fuel tube channels qualitatively and quantitatively.     

固体氧化物燃料电池电化学与热分析耦合的二维模型

计算机模拟是燃料电池设计的一个重要辅助工具。本文在分析了燃料电池的电学和热学性质之后,设计了一套二维平板型团体氧化物燃料电池(SOFC)的模拟软件,软件能回答诸如温度场分布、电流场分布、输出功率等问题,作为应用例子,该软件被用于分析比较不同气流流向(交叉流、并流、对流)设计的燃料电池工作情况,指出了它们的优缺点,为燃料电池设计提供了有益的信息。     

Analysis of temperature and pressure changes in liquefied natural gas (LNG) cryogenic tanks

Liquefied natural gas (LNG) is being developed as a transportation fuel for heavy vehicles such as trucks and transit buses, to lessen the dependency on oil and to reduce greenhouse gas emissions. The LNG stations are properly designed to prevent the venting of natural gas (NG) from LNG tanks, which can cause evaporative greenhouse gas emissions and result in fluctuations of fuel flow and changes of fuel composition. Boil-off is caused by the heat added into the LNG fuel during the storage and fueling. Heat can leak into the LNG fuel through the shell of tank during the storage and through hoses and dispensers during the fueling. Gas from tanks onboard vehicles, when returned to LNG tanks, can add additional heat into the LNG fuel. A thermodynamic and heat transfer model has been developed to analyze different mechanisms of heat leak into the LNG fuel. The evolving of properties and compositions of LNG fuel inside LNG tanks is simulated. The effect of a number of buses fueled each day on the possible total fuel loss rate has been analyzed. It is found that by increasing the number of buses, fueled each day, the total fuel loss rate can be reduced significantly. It is proposed that an electric generator be used to consume the boil-off gas or a liquefier be used to re-liquefy the boil-off gas to reduce the tank pressure and eliminate fuel losses. These approaches can prevent boil-off of natural gas emissions, and reduce the costs of LNG as transportation fuel.     

微乳化乙醇柴油热物性计算与分析

车用清洁型微乳化油是内燃机的理想代用燃料之一．微乳化油热物性参数难以计算,从而影响在内燃机上对它的定量计算研究．以微乳化乙醇柴油为例,用经验公式计算其蒸发焓、生成焓、液体比热容、导热率和微乳化油蒸气的扩散系数,分析了温度和压力以及不同溶醇量对热物性参数的影响规律,为微乳化油热物性参数的计算提供一种工程方法．结果表明：随着温度的增加,微乳化乙醇柴油蒸发焓、导热率降低,定压比热容和微乳化油蒸气扩散系数增加;随着压力增加,微乳化油蒸气扩散系数降低;随着混合燃料中乙醇含量的增加,定压比热容和混合气扩散系数均增大,蒸发焓减小;乙醇含量对混合燃料导热率的影响与燃料温度有关,在一定温度下乙醇含量效应发生逆转;微乳化乙醇柴油中乙醇含量增加有利于燃料蒸发．     

Fate of toxic phorbol esters in Jatropha curcas oil by a biodiesel fuel production process

Clean Technologies and Environmental Policy - Biodiesel fuel (BDF) is an important alternative fuel because of the carbon neutral nature of biomass and the exhaustion of fossil fuel resources....     

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.     

Modeling thermal and stress behavior of the fuel–clad interface in monolithic fuel mini-plates

A fuel development and qualification program is in process with the objective of qualifying very high density monolithic low enriched uranium–molybdenum fuel for high-performance research reactors. The monolithic fuel foil creates differences in the mechanical and structural characteristics of the fuel plate because of the planar interface created by the fuel foil and cladding. An initial finite element analysis model has been developed to investigate worst-case scenarios for the basic monolithic fuel plate structure using typical mini-plate irradiation conditions in the Advanced Test Reactor. Initial analysis shows that the stress normal to the fuel–clad interface dominates during irradiation and that the presence of small, rounded delaminations at the interface is not of great concern. However, larger and/or fuel–clad delaminations with sharp corners can create areas of concern, as maximum principal cladding stress, strain, displacement, and peak fuel temperature are all significantly increased. Furthermore, stresses resulting from temperature gradients that cause the plate to bow or buckle in an unconstrained fuel plate configuration is greatly enhanced in a constrained fuel plate configuration. The sensitivities of the model and input parameters are discussed, along with some overlap of initial experimental observations using as-fabricated plate characterization and post-irradiation examination.