Farm wood fuel and energy project

This paper describes the findings of the Farm Wood Fuel and Energy Project. It began in 1991 and ended in 1997 and was undertaken to provide a commercial demonstration for the establishment of 50 hectares of short rotation coppice (SRC) on six farms in southern England and the development of associated marketing activities. The Project:

• — taught farmers how best to grow the crop and will enable them to teach others;

• — determined that winter conditions in the UK are unsuitable for most harvesting equipment trialled and that both harvesting and chip storage need to be re-examined;

• — demonstrated that SRC has the potential to be competitive with fossil fuels;

• — gave confidence to Government to include a Band for energy crops under the NFFO electricity generating procedures

     

Optical investigations of fuel deposition burning in ported fuel injection (PFI) spark-ignition (SI) engine

The present paper discusses the results obtained by experimental investigations of the diffusion-controlled flame near the valves due to fuel film deposition in a single cylinder, ported fuel injection (PFI), four-stroke spark-ignition (SI) engine with a four-valve production head. The engine was equipped with a transparent combustion chamber with a wide quartz window in the bottom.     

Insight into fuel reactivity effects on thermochemical fuel reforming (TFR)

This study uses a port-injection spark-ignition four-cylinder natural gas engine to achieve TFR (Thermochemical fuel reforming) mode. To study the effects of fuel reactivity on combustion, reforming process, emissions and fuel economy, chemicals including n-heptane, PRF50 and isooctane are respectively used as enriched fuel. The results show that the higher the reactivity of the enriched fuel, the better the combustion and cycle stability of the reforming cylinder. However, n-heptane enrichment with high reactivity has the problem of knocking at large equivalence ratio. The enrichment limit of PRF50 is the highest, which combines the properties of n-heptane and isooctane. The H₂ production abilities of three enriched fuels are similar, but that of isooctane is slightly lower under large equivalence ratios. In terms of fuel economy, the three perform similarly at small equivalence ratios. Whereas it’s lower with isooctane enrichment at large equivalence ratios, which is at the expense of increased NOx emission.     

Regional nuclear fuel cycle centres: IAEA study project

A study project on regional nuclear fuel cycle centres was initiated by the International Atomic Energy Agency in 1975 to examine the economic, safety, safeguards and security aspects of a multinational approach to the planning and establishment of nuclear fuel cycle facilities. The study has concentrated on the ‘back end’ of the fuel cycle, covering transport, storage, processing and recycling activities. The results of this study would help any group of interested member states to develop alternative strategies for their present and projected nuclear fuel cycle needs, as well as evolve institutional, legal and other appropriate arrangements for establishing fuel cycle centres on a multinational cooperative basis.     

Performance of a direct methanol fuel cell (DMFC) at low temperature: Cathode optimization

The effects of Pt loading, Nafion content in the cathode and membrane–electrode assembly (MEA) preparation techniques (CCS_cathode/CCS_anode and CCM_cathode/CCS_anode) on the performance of MEAs for direct methanol fuel cells (DMFC) were studied. The MEA performance was analyzed with polarization curves, electrochemical impedance spectroscopy and scanning electron microscopy data. It was shown, that the cathode prepared by the catalyst coated membrane (CCM) method forms a mainly microporous and mesoporous structure, whereas the catalyst coated substrate (CCS) method generates macroporosity together with micropores and mesopores. The power density of the CCM_cathode/CCS_anode typed MEAs strongly depends on the CCM-cathode composition: Pt loading and Nafion content in the cathode. Nafion (10.7 wt.%) was found to be an optimum for DMFC performance, and at this composition, the power density gradually increased with the Pt loading up to 6.0 mg cm⁻². At higher Nafion contents, a significant mass transfer limitation at high Pt loadings occurs. Comparing the CCM and CCS methods of the cathode fabrication, the latter revealed a higher power density, which reached 104 mW cm⁻² at 0.4 V and 70 °C owing to the lack of significant mass transfer limitations. This behavior indicates that in addition to Pt loading and Nafion content, the cathode pore structure is critical to DMFC MEA performance.     

质子交换膜燃料电池

因其具有独特的优点，质子交换膜燃料电池（PEMFC）的市场前景很好，国际上已经形成了一股研究开发热潮。电催化剂、质子交换膜、双极板、燃料、水管理、热管理是质子交换膜燃料电池的关键技术。文章介绍了PEMFC的特点及开发应用状况，综述了PEMFC的研究进展。     

水煤膏管内层流和过渡区的阻力特性

在分析非牛顿流体管内滑移流动机理的基础上,提出了通过计算水煤膏管内流动广义雷诺数ReE来确定其阻力损失的方法。分析结果表明：广义雷诺数不仅适用于管内存在滑移的非牛顿流体流动,同样适用于无滑移的非牛顿和牛顿流体流动。试验结果表明：水煤膏管内定常流动的临界雷诺数约为2100;层流区采用广义雷诺数的沿程阻力系数的计算公式类似于牛顿流体的简单形式,即λ=64／Reg;过渡区的阻力损失近似满足布拉休斯方程,λ=0.316Reg^-0.25。     

Methoxy methane (dimethyl ether) as an alternative fuel for direct fuel cells

The electrooxidation of methoxy methane (dimethyl ether) was studied at different Pt-based electrocatalysts in a standard three-electrode electrochemical cell. It was shown that alloying platinum with ruthenium or tin leads to shift the onset of the oxidation wave towards lower potentials. On the other hand, the maximum current density achieved was lower with a bimetallic catalyst compared to that obtained with a Pt catalyst. The direct oxidation of dimethoxy methane in a fuel cell was carried out with Pt/C, PtRu/C and PtSn/C catalysts. When Pt/C catalyst is used in the anode, it was shown that the pressure of the fuel and the temperature of the cell played important roles to enhance the fuel cell electrical performance. An increase of the pressure from 1 to 3 bar leads to multiply by two times the maximum achieved power density. An increase of the temperature from 90 to 110 °C has the same effect. When PtRu/C catalyst is used in the anode, it was shown that the electrical performance of the cell was only a little bit enhanced. The maximum power density only increased from 50 to 60 mW cm⁻² at 110 °C using a Pt/C anode and a Pt_0.8Ru_0.2/C anode, respectively. But, the maximum power density is achieved at lower current densities, i.e. higher cell voltages. The addition of ruthenium to platinum has other effect: it introduces a large potential drop at relatively low current densities. With the Pt_0.5Ru_0.5/C anode, it has not been possible to applied current densities higher than 20 mA cm⁻² under fuel cell operating conditions, whereas 250 and almost 400 mA cm⁻² were achieved with Pt_0.8Ru_0.2/C and Pt/C anodes. The Pt_0.9Sn_0.1/C anode leads to higher power densities at low current densities and to the same maximum power density as the Pt/C anode.     

Parametric study on direct ethanol fuel cell (DEFC) performance and fuel crossover

A parametric study was carried out to investigate the effect of fuel concentration (0.5 M–3.0 M), operating temperature (ambient temperature to 85 °C), flow rate of ethanol (0.5–5.0 mL min⁻¹) and air (100–600 mL min⁻¹) on the direct ethanol fuel cell (DEFC) performance. The operations were conducted in three operational modes, namely, passive, semi passive, and active modes, and power generation were measured. Ethanol crossover was indicated by the carbon dioxide (CO₂) concentration present at the cathode outlet and measured by using a CO₂ analyzer. Results indicated that DEFC performance increased with the increase of ethanol concentration, and ethanol and oxidant flow rate increased with temperature until DEFC reaches the optimum conditions, i.e., concentration and flow rate. Meanwhile, the DEFC performance significantly and proportionally increased with operation temperature and reached values of up to 8.70 mW cm⁻² and 85 °C at stable conditions. Furthermore, fuel crossover, that is, ethanol flux, increased in proportion to the ethanol concentration, i.e., 3.71 × 10⁻⁴ g m⁻² s⁻¹ and 8.79 × 10⁻⁴ g m⁻² s⁻¹ for 0.5 M and 3.0 M ethanol concentration, respectively. At different modes of operation, the active DEFC system exhibited the highest performance, followed by the semi passive and passive DEFC system. These results indicated that optimizing ethanol, oxidant flow rate and temperature would enhance the mass transport in anodes and cathodes, and hence improve the electrochemical reactions and DEFC performance.     

Exergonomics of an EOR (OCDOPUS) project

The combined production of power, carbon dioxide, process steam, hot water, and compressed nitrogen for EOR is considered. Exergy-flow diagrams are used to evaluate plant efficiency. The exergy efficiency of the plant is defined as the sum of the exergy outputs divided by the exergy of the consumed fuel. Estimations of the invested exergy, net exergy coefficient and the sum of the specific exergy consumption are presented.     

Valveless piezoelectric micropump for fuel delivery in direct methanol fuel cell (DMFC) devices

Fuel cells are being considered as an important technology that can be used for various power applications. For portable electronic devices such as laptops, digital cameras, cell phone, etc., the direct methanol fuel cell (DMFC) is a very promising candidate as a power source. Compared with conventional batteries, DMFC can provide a higher power density with a long-lasting life and recharging which is almost instant. However, many issues related to the design, fabrication and operation of miniaturized DMFC power systems still remain unsolved. Fuel delivery is one of the key issues that will determine the performance of the DMFC. To maintain a desired performance, an efficient fuel delivery system is required to provide an adequate amount of fuel for consumption and remove carbon dioxide generated from fuel cell devices at the same time. In this paper, a novel fuel delivery system combined with a miniaturized DMFC is presented. The core component of this system is a piezoelectric valveless micropump that can convert the reciprocating movement of a diaphragm activated by a piezoelectric actuator into a pumping effect. Nozzle/diffuser elements are used to direct the flow from inlet to outlet. As for DMFC devices, the micropump system needs to meet some specific requirements: low energy consumption but a sufficient fuel flow rate. Based on theoretical analysis, the effect of piezoelectric materials properties, driving voltage, driving frequency, nozzle/diffuser dimension, and other factors on the performance of the whole fuel cell system will be discussed. As a result, a viable design of a micropump system for fuel delivery can be achieved and some simulation results will be presented as well.     

Dimethyl ether (DME) as an alternative fuel

With ever growing concerns on environmental pollution, energy security, and future oil supplies, the global community is seeking non-petroleum based alternative fuels, along with more advanced energy technologies (e.g., fuel cells) to increase the efficiency of energy use. The most promising alternative fuel will be the fuel that has the greatest impact on society. The major impact areas include well-to-wheel greenhouse gas emissions, non-petroleum feed stocks, well-to-wheel efficiencies, fuel versatility, infrastructure, availability, economics, and safety. Compared to some of the other leading alternative fuel candidates (i.e., methane, methanol, ethanol, and Fischer–Tropsch fuels), dimethyl ether appears to have the largest potential impact on society, and should be considered as the fuel of choice for eliminating the dependency on petroleum.DME can be used as a clean high-efficiency compression ignition fuel with reduced NO_x, SO_x, and particulate matter, it can be efficiently reformed to hydrogen at low temperatures, and does not have large issues with toxicity, production, infrastructure, and transportation as do various other fuels. The literature relevant to DME use is reviewed and summarized to demonstrate the viability of DME as an alternative fuel.     

垃圾衍生燃料(RDF)技术概述

文章综述了国外垃圾衍生燃料（RDF）的技术、产品和应用，结合中国垃圾的具体特点，提出中国发展RDF技术的思路。     

Nanocatalyst for direct methanol fuel cell (DMFC)

Nanotechnology has recently been applied to direct methanol fuel cells (DMFC), one of the most suitable and promising options for portable devices. With characteristics such as low working temperature, high energy-conversion efficiency and low emission of pollutants, DMFCs may help solve the future energy crisis. However, a significant limitation to DMFC includes slow reaction kinetics, which reduces performance and power output. Recently, research has focused on increasing the performance and activity of catalysts. Catalysts composed of small, metallic particles, such as platinum and ruthenium, supported on nanocarbons or metal oxides are widely used in DMFC. Thus, this paper presents an overview of the development of nanocatalysts for DMFC. Particularly, this review focuses on nanocatalyst structure, catalyst support, and challenges in the synthesis of nanocatalyst. This paper also presents computational approaches for theoretical modeling of nanomaterials such as carbon nanotubes (CNT) through molecular dynamic techniques.     

Autoignition of surrogate biodiesel fuel (B30) at high pressures: Experimental and modeling kinetic study

Ignition delay times of surrogate biodiesel fuels were measured in a high-pressure shock tube over a wide range of experimental conditions (pressures of 20 and 40 bar, equivalence ratios in the range 0.5–1.5, and temperatures ranging from 700 to 1200 K). A detailed chemical kinetic mechanism developed for the oxidation of a biodiesel fuel and a B30 biodiesel surrogate (49% n-decane, 21% 1-methylnaphthalene, and 30% methyloctanoate in mol%) was used to simulate the present experiments. Cross reactions between radicals from the three fuel components and reactions of methylnaphthalene oxidation recently proposed in the literature were introduced into the model in order to improve ignition delay time predictions at low temperatures. The new scheme (7865 reversible reactions and 1975 species) yields improved model predictions of concentration profiles measured earlier in a jet-stirred reactor, and also represents fairly well the present experimental data over the entire range of conditions of this study. Sensitivity analyses and reaction path analyses were used to rationalize the results.     

Fuel cell mobile lighting: A fuel cell market transformation project

We report the results of a project aimed to introduce proton exchange membrane (PEM) hydrogen fuel cell technology into aviation ground support equipment (GSE) and rental construction equipment. The purpose of the project was to design, build, field-test and then commercialize fuel cell equipment that is superior to its diesel counterpart. The commercializing of this hydrogen-based technology will help to start the process of displacing diesel fuel use in aviation GSE and in mobile construction equipment. We describe a hydrogen fuel cell mobile lighting tower (H₂LT) that combines hydrogen stored as a high pressure gas, PEM fuel cell technology, and advanced lighting into a single unit with uses in aviation and construction. We assembled a project team of 15 institutional partners combining new technology expertise (hydrogen, fuel cells), equipment mass manufacturing capability (mobile light towers, lighting) and influential end-users to field test the H₂LT in real-world use in diverse environments. Seed funding provided by Boeing enabled additional funding from the U.S. Department of Energy (DOE) and a preponderance of in-kind contributions from the industrial partners. Prototype units were constructed and field tested in the entertainment industry, at the San Francisco International Airport, at the NASA Kennedy Space Center, with the California Department of Transportation (Caltrans), and with the Connecticut Department of Transportation. The goals of these approximately year-long field tests were to assess operation of the H₂LT technology in a wide variety of potentially corrosive environments (cold, wet, hot, humid, salty air) performing a wide variety of tasks, to reduce diesel emissions at these locations, and to help promote hydrogen PEM technology in new influential markets. The H₂LT proved to be exceptionally durable in these diverse environments, demonstrating the compatibility of PEM fuel cells and high-pressure hydrogen storage with the construction equipment application. Results from the field tests are discussed, including system performance (efficiency, duration, durability) and the efficacy of refueling the system by different methods (H₂ stations, mobile refueling). The H₂LT system is compared directly to a comparable diesel-fueled light tower with regard to size, performance and emissions savings. Overall, end users were pleased with the performance of the H₂LT, noting the lack of emissions and exceptionally low noise level. Recommendations for improvement were also collected and will be discussed. Two types of lighting used on the H₂LT (plasma, LED) were characterized by U.C. Davis in collaboration with Caltrans. LED lighting was found to be the most energy efficient and robust lighting technology for the highly mobile H₂LT application. The technical “lessons-learned” are reviewed, along with the plans for commercialization of the H₂LT technology by Multiquip Inc. Finally, the benefits to the industrial participants of the project organization are described.     

A fuel cell powered autonomous surface vehicle: The Eco-SWAMP project

Autonomous surface vehicles are becoming consolidated robotic tools for marine, coastal and inland surveys. Autonomous surface vehicles are usually equipped with electronic instruments to perform remotely controlled or autonomous geo-morphological, biological, chemical, physical analyses and data collection. Actually, well-established solutions provide battery power but the research focuses on introducing a fuel cell to decrease the environmental impact meanwhile increasing the cruising range. In this paper, the design of the Eco-SWAMP, a fuel cell powered autonomous surface vehicle, is presented starting from its battery-powered version, the SWAMP prototype. The experimental power consumption profile of the SWAMP during four missions is analysed to define the primary energy sources ratings of the Eco-SWAMP. After a commercial choice of primary sources, power management algorithms are designed and compared in MATLAB/Simulink environment by simulation results. The proposed procedure can be easily applied to any autonomous marine vehicle.     

Performance of miniaturized direct methanol fuel cell (DMFC) devices using micropump for fuel delivery

A fuel cell is a device that can convert chemical energy into electricity directly. Among various types of fuel cells, both polymer electrolyte membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs) can work at low temperature (<80 °C). Therefore, they can be used to supply power for commercial portable electronics such as laptop computers, digital cameras, PDAs and cell phones. The focus of this paper is to investigate the performance of a miniaturized DMFC device using a micropump to deliver fuel. The core of this micropump is a piezoelectric ring-type bending actuator and the associated nozzle/diffuser for directing fuel flow. Based on the experimental measurements, it is found that the performance of the fuel cell can be significantly improved if enough fuel flow is induced by the micropump at anode. Three factors may contribute to the performance enhancement including replenishment of methanol, decrease of diffusion resistance and removal of carbon dioxide. In comparison with conventional mini pumps, the size of the piezoelectric micropump is much smaller and the energy consumption is much lower. Thus, it is very viable and effective to use a piezoelectric valveless micropump for fuel delivery in miniaturized DMFC power systems.     

Diesel fuel processor for PEM fuel cells: Two possible alternatives (ATR versus SR)

There are large efforts in exploring the on-board reforming technologies, which would avoid the actual lack of hydrogen infrastructure and related safety issues. From this view point, the present work deals with the comparison between two different 10 kW_e fuel processors (FP) systems for the production of hydrogen-rich fuel gas starting from diesel oil, based respectively on autothermal (ATR) and steam-reforming (SR) process and related CO clean-up technologies; the obtained hydrogen rich gas is fed to the PEMFC stack of an auxiliary power unit (APU). Based on a series of simulations with Matlab/Simulink, the two systems were compared in terms of FP and APU efficiency, hydrogen concentration fed to the FC, water balance and process scheme complexity. Notwithstanding a slightly higher process scheme complexity and a slightly more difficult water recovery, the FP based on the SR scheme, as compared to the ATR one, shows higher efficiency and larger hydrogen concentration for the stream fed to the PEMFC anode, which represent key issues for auxiliary power generation based on FCs as compared, e.g. to alternators.     

Mechanical performance of reactive-air-brazed (RAB) ceramic/metal joints for solid oxide fuel cells at ambient temperature

Mechanical integrity of the sealants in planar SOFC stacks is a key prerequisite for reliable operation. In this respect joining with metals rather than brittle glass-ceramics is considered to have advantages. Hence, as one of the joining solutions for SOFCs of planar design, reactive air brazing of ceramic cells into metallic frames gains increasing interest.Fracture experiments are carried out to characterize fracture energy and failure mechanisms of silver-based reactive-air-brazes, used for joining the zirconia electrolytes of anode supported planar cells with metallic Crofer22APU frames. The specimens are mechanically tested in notched beam bending geometry. In-situ observation in optical and SEM resolution reveals specific failure mechanisms. The influence of braze formulation and associated interfacial reactions on the crack path location is addressed. Discussion of the results focuses in particular on the role of oxide scale formation.