固液组分与混合燃料细观尺度的相关性

给出固体金属粉燃料颗粒尺寸随机分布的分形表示,建立了组分比例、固体燃料颗粒尺度特征与ＦＡＥ混合燃料细观结构的相关性。通过实 由固,液燃料组分比例关系,确定ＦＡＥ混合燃料细观尺度的过程和方法。讨论了ＦＡＥ混合燃料达到饱和状态的临界条件。     

燃料空气炸药能量输出的讨论

对燃料空气炸药（ＦＡＥ）的能量输出指标进行了讨论。认为以ＴＮＴ当量的概念来衡量ＦＡＥ的能量指标不能确切反映ＦＡＥ的实际毁伤效果。提出以ＦＡＥ爆炸后压力场的超压或冲量为依据，针对不同目标得出相应的破坏范围（威力圈）来表示ＦＡＥ的威力指标。     

高能固态FAE燃料贮存寿命研究

通过测量高温加速老化试验条件下固态ＦＡＥ燃料中铝粉活性的变化,分别采用贝瑟洛特（Ｂｅｒｔｈｌｏｔ）方程预测法（火药法）和阿累尼乌斯（Ａｒｒｈｅｎｉｕｓ）方程预测法（固体推进剂法）进行燃料贮存寿命研究,通过试验和分析初步确定贝瑟洛特方程预测法（火药法）为高能固态ＦＡＥ燃料的贮存寿命预测方法。     

FAE燃料抛撒与云雾状态的控制

燃料抛撒与云雾状态的控制是提高ＦＡＥ威力的重要途径之一,本文讨论了与燃料抛撒和雾化有关的问题,并在实验基础上归纳得到云爆条件的基本关系式。     

固相一次起爆型FAE燃料的优化选择

为从品种繁多、特性各异的燃料中选择较佳的燃料配方,以提高固相一次起爆型FAE的威力,利用一次起爆型燃料空气炸药比两次起爆型燃料空气炸药的燃料选择和云爆技术联系更紧密的特点,建立了燃料优化设计系统模型.新模型的建立为选择较佳的燃料配方提供了可能.     

燃料空气炸药威力评判的讨论

ＦＡＥ对目标的毁伤作用，主要由爆炸场参数（超压－冲量）决定。本文提出了几种评判ＦＡＥ威力的方法，并对它们进行了分析、比较和讨论。     

燃料空气炸药,武器化及其效能

燃料空气炸药(FAE)的定义如下:FAE是能从空气中获取它所需的绝大部分或全部氧气的一种可爆炸材料.燃料空气炸药有两个极独特的性能,一是它本身含有少量氧或不含氧,因而重量效率高;二是爆炸在很大面积上进行,与常规高级炸药的点起爆特性相比,其冲量要大.常规高级炸药粉末(high explosive powders)和核炸药是例外情况,本文对此例外不作详细论述.     

分散药起爆方式控制FAE燃料分散的数值模拟

为初步预示燃料的后期分散效应,运用ANSYS／DYNA3D程序,选择了四种起爆方式数值模拟分散药对FAE炸弹壳体起始阶段的破裂及运动过程。结果表明,分散药起爆方式即爆轰波传播方向对燃料分散有显著的影响,分散药起爆方式在FAE的研究中应受到特别重视。     

中心药量对燃料的抛散作用

通过燃料抛散过程的高速运动分析系统观测,分析燃料抛散物理过程的不同阶段,阐述了中心药对燃料的抛散作用。研究结果表明,燃料抛散过程可以分为加速运动阶段、减速运动阶段和湍流运动阶段。在一定范围内,燃料抛散的最终云雾半径与FAE装置中心药量无关,它取决于燃料抛散的加速运动阶段和减速运动阶段。在这两个阶段中,燃料分散主要发生在径向。燃料分散的过程与中心药量密切相关。燃料分散的不同阶段应用不同的力学模型来描述。     

固体电解质燃料电池的进展

固体电解质燃料电池的进展孙宏林，田玫ＲＥＦＬＩＥＣＴＩＯＮＯＦＳＴＡＴＩＣＡＬＰＲＯＰＥＲＴＹＩＮＣＡＲＮＯＴＣＹＣＬＥ１前言固体电解质燃料电池，又称固体氧化物电解质燃料电池，简称ＳＯＦＣ（ＳｏｌｉｄＱｘｉｄｅＦｕｅｌＣｅｌｌ），是一种高温燃料电池，...     

Combustion and emissions behavior for ethanol–gasoline blends in a single cylinder engine

This paper investigates the effect of using gasoline–ethanol mid-level blends (0–20% ethanol) on engine performance and exhausts emissions on a single cylinder engine by AVL model 5401, spark ignited and electronically controlled with DOHC. Engine tests were conducted for different lambda values, brake power and brake specific fuel consumption, while exhaust emissions were analyzed for carbon monoxide, unburned hydrocarbons and nitrogen oxides. Using blends at different proportions for a steady state of 2000 rpm at partial charge minimizing load and speed variations at a minimum in order to prevent them from being a measurable factor. Results showed that at constant mass fuel rates, the increase in burning rate associated with ethanol is tempered by the process combustion speed reduction related to the enleanment proportional to the ethanol added to gasoline. Blends up to 10% have marginal effects in combustion rates when compared to non-oxygenated fuels, but for 20%, combustion process slows down and increases cyclic dispersion in the results, the effect in fuel consumption observed was lower than predicted by the reduction of energy content in the gasoline, suggesting positive effects in combustion efficiency.     

PEM fuel cell current regulation by fuel feed control

We demonstrate that the power output from a PEM fuel cell can be directly regulated by limiting the hydrogen feed to the fuel cell. Regulation is accomplished by varying the internal resistance of the membrane-electrode assembly in a self-draining fuel cell with the effluents connected to water reservoirs. The fuel cell functionally operates as a dead-end design where no gas flows out of the cell and water is permitted to flow in and out of the gas flow channel. The variable water level in the flow channel regulates the internal resistance of the fuel cell. The hydrogen and oxygen (or air) feeds are set directly to stoichiometrically match the current, which then control the water level internal to the fuel cell. Standard PID feedback control of the reactant feeds has been incorporated to speed up the system response to changes in load. With dry feeds of hydrogen and oxygen, 100% hydrogen utilization is achieved with 130% stoichiometric feed on the oxygen. When air was substituted for oxygen, 100% hydrogen utilization was achieved with stoichiometric air feed. Current regulation is limited by the size of the fuel cell (which sets a minimum internal impedance), and the dynamic range of the mass flow controllers. This type of regulation could be beneficial for small fuel cell systems where recycling unreacted hydrogen may be impractical.     

制备工艺对微乳化柴油稳定性能的影响

为了考察制备工艺对微乳化柴油稳定性能的影响,采用单因素变化试验和正交试验设计安排试验,系统分析了制备微乳化柴油时的温度、搅拌速度、搅拌方式、试剂的添加顺序以及各工序搅拌时间对其稳定性能的影响。结果表明:温度为25～35℃,搅拌速度为300～500r/m in,添加顺序为乳化剂和柴油先混合,再加入水,最后加入助乳剂,各工序搅拌时间均为5m in时所制备的微乳化柴油稳定性好。结论为制备微乳化柴油时温度、搅拌速度、搅拌时间以及添加顺序对其稳定性能影响较大,搅拌方式对其稳定性能影响较小。     

Detached eddy simulation of particle dispersion in a gas-solid two-phase fuel rich/lean burner flow

To predict the particle dispersion in the burner jet is of great importance in industrial application and in the designing of coal burner with good performance. The objective of this study was to numerically investigate the particle dispersion mechanisms in the gas-solid two-phase jet from a fuel rich/lean burner. The detached-eddy-simulation (DES) approach was employed to study the turbulent flow in the fuel rich/lean separator and the gas-solid multiphase jet from the exit of a fuel rich/lean burner. The vortex shedding process was simulated and its effect on the fuel rich/lean separating performance was evaluated. Combined with the Lagrangian tracking procedure for the particle phase, the coal particles with various Stokes numbers equal to 0.000434, 0.043, 1.08, 4.34 (corresponding to particle diameter 1, 10, 50, 100 μm, respectively) in the gas-solid fuel rich/lean jet were studied, which shows that although there are coherent vortex structures behind the central partition plate, these vorticities are small, the fuel-rich stream and the fuel lean stream will not mix quickly downstream of the exit of the nozzle. The large vortex structures at the jet outer boundary are the main factors that make the small particles to mix together. The coal particles with large Stokes number (St>1) disperse very slowly in the jet flow, which realizes the fuel rich/lean combustion in a rather long distance downstream the exit of the nozzle, resulting in low NO_x emissions.     

Preferential CO oxidation over Pt/3A zeolite catalysts in H2-rich gas for fuel cell application

Even traces of CO in the hydrogen-rich gas fed to proton exchange membrane fuel cells (PEMFC) poison the platinum anode electrode and dramatically decrease the cell power output. In this work, several 1%Pt catalysts, all on 3A-type zeolite support, were prepared starting from different precursors and employing different methods: cation exchange (CE), wet impregnation (WI) and incipient wetness impregnation (IWI). The catalysts were characterised in terms of platinum dispersion and tested under realistic conditions in the quest of a catalyst for the removal of CO via the CO preferential oxidation (CO-PROX) reaction. The best catalytic performance was shown by the 1%Pt–3A catalyst prepared by IWI starting from Pt(NH₃)₄Cl₂ as a precursor, thanks to its highest platinum dispersion.     

A novel technique for particle tracking in cold 2-dimensional fluidized beds—simulating fuel dispersion

This paper presents a novel technique for particle tracking in 2-dimensional fluidized beds operated under ambient conditions. The method is applied to study the mixing mechanisms of fuel particles in fluidized beds and is based on tracking a phosphorescent tracer particle by means of video recording with subsequent digital image analysis. From this, concentration, velocity and dispersion fields of the tracer particle can be obtained with high accuracy. Although the method is restricted to 2-dimensional, it can be applied under flow conditions qualitatively resembling a fluidized-bed combustor. Thus, the experiments cover ranges of bed heights, gas velocities and fuel-to-bed material density and size ratios typical for fluidized-bed combustors. Also, several fluidization regimes (bubbling, turbulent, circulating and pneumatic) are included in the runs.A pattern found in all runs is that the mixing pattern of the tracer (fuel) solids is structured in horizontally aligned vortexes induced by the bubble flow. The main bubble paths always give a low concentration of tracer solids and with the tracer moving upwards, while the downflow of tracer particles in the dense bottom bed is found to take place in zones with low bubble density and at the sidewalls. The amount of bed material (bed height) has a strong influence on the bottom bed dynamics (development and coalescence of bubbles) and, consequently, on the solids mixing process. Local dispersion coefficients reach maximum values around the locations of bubble eruptions, while, in the presence of a dense bottom bed, an increase in fluidization velocity or amount of bed material enhances dispersion. Dispersion is found to be larger in the vertical than in the horizontal direction, confirming the critical character of lateral fuel dispersion in fluidized-bed combustors of large cross section.     

A Fuel‐Flexible Alkaline Direct Liquid Fuel Cell

We constructed a fuel‐flexible fuel cell consisting of an alkaline anion exchange membrane, palladium anode, and platinum cathode. When an alcohol fuel was used with potassium hydroxide added to the fuel stream and oxygen was the oxidant, the following maximum power densities were achieved at 60 °C: ethanol (128 mW cm⁻²), 1‐propanol (101 mW cm⁻²), 2‐propanol (40 mW cm⁻²), ethylene glycol (117 mW cm⁻²), glycerol (78 mW cm⁻²), and propylene glycol (75 mW cm⁻²). We also observed a maximum power density of 302 mW cm⁻² when potassium formate was used as the fuel under the same conditions. However, when potassium hydroxide was removed from the fuel stream, the maximum power density with ethanol decreased to 9 mW cm⁻² (using oxygen as oxidant), while with formate it only decreased to 120 mW cm⁻² (using air as the oxidant). Variations in the performance of each fuel are discussed. This fuel‐flexible fuel cell configuration is promising for a number of alcohol fuels. It is especially promising with potassium formate, since it does not require hydroxide added to the fuel stream for efficient operation.     

A novel multigrid technique for Lagrangian modeling of fuel mixing in fluidized beds

This paper presents a novel Lagrangian approach to model fuel mixing in gas–solid fluidized beds. In the mixing process, fuel particles are considerably larger than the inert bed material and therefore, the present work proposes three grids to account for the difference in size between the fuel particles and inert solids. The information between the grids is exchanged using an algorithm presented in the paper. A statistical method has been developed to analyze the distribution of the fuel particles in the bed. The results for the preferential positions, velocity vectors and horizontal dispersion coefficients are compared with experimental data in a bed applying simplified scaling relationships for different operating conditions. The effects of initial bed height and inlet gas velocity on the fuel mixing are investigated.It is found that the proposed Lagrangian modeling can capture the complex pattern of the movement of the fuel particles, in spite of the large difference in diameter between inert and fuel particles.     

Effect of Nickel Addition on Ceria‐Supported Platinum Catalysts for Medium‐Temperature Shift Reaction in Fuel Processors

Medium‐temperature shift reaction (MTS, 280–340 °C) has received much attention for use in fuel processors. In this study, bifunctional Pt‐Ni/CeO₂ catalysts were prepared by different Pt (0.1–0.5 %) and Ni (5–20 %) loadings, and investigated for MTS reaction. X‐ray diffraction, N₂ adsorption and temperature‐programmed reduction tests were used to characterize the prepared samples. The results showed that Pt‐Ni bimetallic catalysts have higher CO conversion in comparison to Pt/CeO₂ monometallic catalyst. Furthermore, the sequential synthesis method of Pt and Ni impregnation was preferred to the simultaneous one, which is due to the better Pt dispersion on catalytic surface. Steam to carbon ratio variations study showed the maximum CO conversion to be in the range of 4.5.     

Comparative evaluation of performance and emission characteristics of jatropha, karanja and polanga based biodiesel as fuel in a tractor engine

Non-edible jatropha (Jatropha curcas), karanja (Pongamia pinnata) and polanga (Calophyllum inophyllum) oil based methyl esters were produced and blended with conventional diesel having sulphur content less than 10 mg/kg. Ten fuel blends (Diesel, B20, B50 and B100) were tested for their use as substitute fuel for a water-cooled three cylinder tractor engine. Test data were generated under full/part throttle position for different engine speeds (1200, 1800 and 2200 rev/min). Change in exhaust emissions (Smoke, CO, HC, NO_x, and PM) were also analyzed for determining the optimum test fuel at various operating conditions. The maximum increase in power is observed for 50% jatropha biodiesel and diesel blend at rated speed. Brake specific fuel consumptions for all the biodiesel blends with diesel increases with blends and decreases with speed. There is a reduction in smoke for all the biodiesel and their blends when compared with diesel. Smoke emission reduces with blends and speeds during full throttle performance test.