二甲醚用作柴油机燃料的进展

介绍二甲醚作为柴油发动机燃料的进展 ,有关发动机的性能、微粒排放、燃料喷射、磨损和密封、着火延迟及安全性能问题     

A study of the direct dimethyl ether fuel cell using alkaline anolyte

The electrooxidation behavior of dimethyl ether (DME) dissolved in acidic, neutral or alkaline anolyte has been studied. The cyclic voltammetry measurements reveal that DME in alkaline anolyte demonstrates higher electrooxidation reactivity than that in acidic or neutral anolyte. With increasing the NaOH concentration in the anolyte, the electrooxidation reactivity of DME can be further improved. Direct dimethyl ether fuel cells (DDFCs) are assembled by using Nafion membrane as the electrolyte, Pt/C as the cathode catalyst, and Pt-Ru/C as the anode catalyst. It is found that the use of alkaline anolyte can significantly improve the performance of DDFCs. A maximum power density of 60 mW cm⁻² has been achieved when operating the DDFC at 80 °C under ambient pressure.     

Life cycle assessment of three types of hydrogen production methods using solar energy

A comprehensive life cycle assessment (LCA) is carried out for three methods of hydrogen production by solar energy: hydrogen production by PEM water electrolysis coupling photothermal power generation, hydrogen production by PEM water electrolysis coupling photovoltaic power generation, and hydrogen production by thermochemical water splitting method using S–I cycle coupling solar photothermal technology. The assessment also contains an evaluation of four environmental factors which are global warming potential, acidification potential, ozone depletion potential, and nutrient enrichment potential. After conducting a quantitative analysis of all three methods with environmental factors being considered, a conclusion has been drawn: The global warming potential and the acidification potential of the thermochemical water splitting by S–I cycle coupling solar photothermal technology are 1.02 kg CO₂-eq and 6.56E-3 kg SO₂-eq. And this method has significant advantages in the environmental impact of the whole ecosystem.     

Dimethyl ether as alternative fuel for CI engine and vehicle

As a developing and the most populous country in the world, China faces major challenges in energy supply and environmental protection. It is of great importance to develop clean and alternative fuels for internal combustion engines. On the basis of researches on DME engine and vehicle at Shanghai Jiaotong University in the last twelve years, fuel injection, combustion, performance and exhaust emissions of DME engine and DME vehicle are introduced in this paper. The results indicate that DME engines can achieve high thermal efficiency and ultra low emissions, and will play a significant role in meeting the energy demand while minimizing environmental impact in China.     

Life cycle assessment of various hydrogen production methods

A comprehensive life cycle assessment (LCA) is reported for five methods of hydrogen production, namely steam reforming of natural gas, coal gasification, water electrolysis via wind and solar electrolysis, and thermochemical water splitting with a Cu–Cl cycle. Carbon dioxide equivalent emissions and energy equivalents of each method are quantified and compared. A case study is presented for a hydrogen fueling station in Toronto, Canada, and nearby hydrogen resources close to the fueling station. In terms of carbon dioxide equivalent emissions, thermochemical water splitting with the Cu–Cl cycle is found to be advantageous over the other methods, followed by wind and solar electrolysis. In terms of hydrogen production capacities, natural gas steam reforming, coal gasification and thermochemical water splitting with the Cu–Cl cycle methods are found to be advantageous over the renewable energy methods.     

Dimethyl ether as alternative fuel for CI engine and vehicle

As a developing and the most populous country in the world, China faces major challenges in energy supply and environmental protection. It is of great importance to develop clean and alternative fuels for internal combustion engines. On the basis of researches on DME engine and vehicle at Shanghai Jiaotong University in the last twelve years, fuel injection, combustion, performance and exhaust emissions of DME engine and DME vehicle are introduced in this paper. The results indicate that DME engines can achieve high thermal efficiency and ultra low emissions, and will play a significant role in meeting the energy demand while minimizing environmental impact in China.     

车用燃料生命周期评估

以国际标准化组织的生命周期评价标准为依据,确定了车用燃料生命周期评估的系统边界和评价指标,给出了模型主要的计算公式,并进行了国外车用燃料全生命周期的能源消耗和排放评价。     

Potential of hydrolyzed oxymethylene dimethyl ether for the suppression of fuel crossover in polymer electrolyte fuel cells

Fuel crossover is a crucial issue for polymer electrolyte fuel cells (PEFCs) supplied directly with liquid fuels. Therefore, finding a type of fuel with a low fuel crossover rate is required. In this study, we investigated fuel crossover characteristics for oxymethylene dimethyl ether (OME), which has attracted attention for use in engines, and compared it with methanol. Cell performance tests and exhaust gas analyses showed that fully hydrolyzed OME (h-OME), which consisted of methanol and formaldehyde, yields high cell performance at high fuel concentrations, due to the low fuel crossover rate, compared with a direct methanol fuel cell (DMFC). To clarify a factor suppressing fuel crossover, h-OME's effective diffusion coefficient in the membrane was measured. Although an effective diffusion coefficient for fuels like methanol commonly increases with increased fuel's concentration, h-OME's effective diffusion coefficient decreased with increased fuel concentration, leading to a low fuel crossover rate at high h-OME concentrations.     

Optimum compositions of membrane electrode assemblies (MEAs) for direct dimethyl ether fuel cell

We investigated the effects of the compositions of catalyst layers and diffusion layers on performances of the membrane electrode assemblies (MEAs) for direct dimethyl ether fuel cell. The performances of the MEAs with different thicknesses of Nafion membranes were compared in this work. The optimal compositions in the anode are: 20 wt% Nafion content and 3.6 mg cm⁻² Pt loading in the catalyst layer, and 30 wt% PTFE content and 1 mg cm⁻² carbon black loading in the diffusion layer. In the cathode, MEA with 20 wt% Nafion content in the catalyst layer and 30 wt% PTFE content in the diffusion layer presented the optimal performance. The MEA with Nafion 115 membrane displayed the highest maximum power density of 46 mW cm⁻² among the three MEAs with different Nafion membranes. Copyright © 2009 John Wiley & Sons, Ltd.     

Life cycle energy and environmental assessment of bio-CNG utilization from cassava starch wastewater treatment plants in Thailand

Global warming, energy security, and the rising costs of oil have added a greater driving force to the development of feasible alternatives to petroleum-based transportation fuels. In parallel, wastes and wastewater generated from various industries should be avoided or converted to energy more in the future in order to reduce environmental problems and provide additional sources of energy. In this aspect, biogas plant is an effective option where gas is produced biologically by the fermentation of animal dungs, sewage, and agricultural residues. To utilize biogas as a transportation fuel, raw biogas has to undergo two major processes: cleaning and upgrading, to achieve natural gas quality. The upgraded biogas (so called bio-methane or bio-CNG) is considered green fuel with respect to environment, climate, and human health. However, the resulting bio-CNG from the processes still needs to be evaluated in terms of greenhouse gas emissions and energy aspects. This paper presents the integrated life cycle energy and environmental assessment of compressed bio-methane gas (CBG or bio-CNG) generated from cassava starch wastewater treatment plant in Thailand. The functional units were set to be 1 MJ of bio-CNG and 1 km of vehicle driven. The system boundary covered six main steps: digestion, purification and upgrading, compression, distribution, refueling, and combustion. The energy analysis result showed that the net energy ratio was higher than one, indicating a net energy gain. For the greenhouse gases aspect, the results showed that the biogas production and biogas upgrading step had the highest impact due to methane loss and high energy consumption. Comparing with other fuels, the global warming potential of bio-CNG was lower than those of fossil-based CNG and gasoline.     

Life Cycle Analysis of wind–fuel cell integrated system

After ratification of the Kyoto Protocol, Canada’s Kyoto greenhouse gas (GHG) emission target is 571 Mt of CO₂ equivalent emitted per year by 2010; however, if current emission trends continue, a figure of 809 Mt is projected by 2010 (Cote C. Basic of clean development mechanism—joint implementation and overview of CDM project cycle, 2003 regional workshop on CDM-JI, February 2003, Halifax). This underscores the need for additional reduction of 240 Mt. The Federal Government Action Plan 2000 aims to reduce this gap from 240 to 65 Mt (Cote C. Basic of clean development mechanism—joint implementation and overview of CDM project cycle, 2003 regional workshop on CDM-JI, February 2003, Halifax). In order to accomplish this goal, renewable energy use in all sectors will be required, and this type of energy is particularly applicable in power generation. Traditional power generation is a major source of greenhouse gas (GHG) emissions after industrial and transportation sectors (Environment Canada. Canada’s Greenhouse Gas Inventory 1990–1998. Final submission to the UNFCCC Secretariat, 2002 [Available from: http://www.ec.gc.ca/climate/resources_reportes-e.html]. Although wind energy, solar power and other forms of renewable energy are non-GHG emitting in their operation, there are GHG emissions in their different stages of life cycle (i.e. material extraction, manufacturing, construction and transportation, etc.). These emissions must be accounted for in order to assess accurately their capacity to reduce GHG emission and meet Kyoto targets. The current trend in electricity generation is towards integrated energy systems. One such proposed system is the wind–fuel cell integrated system for remote communities. This paper presents a detailed Life Cycle Analysis of the wind–fuel cell integrated system for application in Newfoundland and Labrador.The study confirms that wind–fuel integrated system is a zero emission system while in operation. There are significant emissions of GHGs during the production of the various components (wind turbine, fuel cell and electrolyzer). However, the global warming potential (GWP) of wind-integrated system is far lower (at least by two orders of magnitude) than the conventional diesel system, presently used in remote communities.     

Potential for reducing GHG emissions and energy consumption from implementing the aluminum intensive vehicle fleet in China

The automobile industry in China has rapidly developed in recent years which resulted in an increase in gasoline usage and greenhouse gas (GHG) emissions. Focus on climate change has also accelerated to grow pressure on reducing vehicle weight and improving fuel efficiency. Aluminum (Al) as a light metal has demonstrated a great potential for weight savings in applications such as engine blocks, cylinder heads, wheels, hoods, tailgates etc. However, primary Al production requires intensive energy and the cost of Al is more than traditional steel, which may affect the total benefits realized from using Al in automobiles. Therefore, it is very essential to conduct a study to quantify the life cycle GHG emissions and energy consumption if the plan is to achieve fleet-wide Al intensive vehicles.     

Life cycle assessment of an alkaline fuel cell CHP system

A life cycle assessment (LCA) of an alkaline fuel cell based domestic combined heat and power (CHP) system is presented. Literature on non-noble, monopolar cell design and stack construction was reviewed, and used to produce a life cycle inventory for the construction of a 1 kW stack. Inventories for the ancillary components of other commercial fuel cell products were consulted, and combined with information on the fuel processing requirements of alkaline cells to suggest a hypothetical balance of plant that would be required to produce AC electricity and domestic grade heat from natural gas and air.     

Energy intensity and greenhouse gas emission of a purchase in the retail park service sector: An integrative approach

The aim of this paper is to describe the energetic metabolism of a retail park service system under an integrative approach. Energy flow accounting was applied to a case study retail park in Spain, representative of the sector across Europe, after redefining the functional unit to account for both direct energy use (buildings, gardens and outdoor lighting) and indirect energy use (employee and customer transportation). A life cycle assessment (LCA) was then undertaken to determine energy global warming potential (GWP) and some energy intensity and greenhouse gases (GHG) emission indicators were defined and applied. The results emphasise the importance of service systems in global warming policies, as a potential emission of 9.26 kg CO₂/purchase was obtained for the case study, relating to a consumption of 1.64 KOE of energy, of which 21.9% was spent on buildings and 57.9% on customer transportation. Some strategies to reduce these emissions were considered: increased supply, energy efficiency, changes in distribution of modes of transport, changes in location and changes in the mix of land uses. A combination of all of these elements in a new retail park could reduce GHG emissions by more than 50%, as it is planning strategies, which seem to be the most effective.     

Model for developing an eco-driving strategy of a passenger vehicle based on the least fuel consumption

Additional consumption of fuel in an intense traffic condition is inevitable. Excess fuel consumption may be avoided, if an optimal driving strategy is implemented subject to the surrounding condition of a vehicle and existing constraints. Development of an optimal driving strategy has been the subject of eco-driving. A model of optimal driving strategy has been developed and it has been applied for assessment of eco-driving rules. The model may be categorized as an optimal control and the objective function is minimization of fuel consumption in a given route. Vehicle speed and gear ratio are identified as control variables. The effect of working load has been considered according three engine running processes of Idle, part-load and wide open throttle. The model has then been applied to identify the optimal driving strategy of a vehicle in different traffic congestion based on eco-driving rules.     

Life cycle analysis and cost of a molten carbonate fuel cell prototype

The LCA is a method enabling the performance of a complete study on the environmental impacts of the product, taking into consideration all its life cycle (“from the cradle to the tomb” or, better “from the cradle to the cradle” when also the maximum recycling/reusing of the materials is provided. There are many procedures to perform an LCA of the consumers’ products. In particular, the SUMMA method (Sustainability Multi-criteria Multi-scale Assessment) allows obtaining a number of indices of efficiency and environmental sustainability which make the LCA assessment much more complete and significant. LCA method often represents the basis for an additional assessment of industrial products and processes, the LCC (Life Cycle Costing) which, allowing the association of economic variables to any phase of the life cycle, represents a useful tool for financial planning and management. The case study analysed in the present work concerns an LCA analysis, using the SUMMA method and the LCC of one small size molten carbonate fuel cell, 2.5 kW, assembled in the Fuel Cells Laboratory within the Educational Pole of Terni at the Università degli Studi di Perugia. For sake of completeness of the results, the methods Ecoindicator99 and Impact2002 + were used in the analysis, as implemented in the used calculation software, the SimaPro 7.1 by PRè Consultants. From the registered results, it emerges that the environmental energy sustainability of the analysed element enables its widespread and in-depth employment in the phase subsequent to the optimisation of the connected economic frame; the scenarios opened by the present work envisage great margins of improvements of said aspects in the future experiments.     

Gasification process of palm kernel shell to fuel gas: Pilot-scale experiment and life cycle analysis

This research demonstrates a palm kernel shell gasification system for producing fuel gas, also known as producer gas. Using air as an oxidant, the gasification process converts palm kernel shells into fuel gas which contains combustible gases, such as hydrogen, carbon monoxide, and methane with nitrogen dominating the composition of the gas. This fuel gas can supply heat via direct combustion or generate electricity for fossil fuel substitution of an internal combustion engine. As a biomass-derived gas, the fuel gas is characterized as carbon-neutral inherently. During the conversion process, the system needs electricity to power the screw feeder, air blowers, and cooling-water pumps, and to rotate the gasifier's bottom plate to take the char out. Based on the experiments, mass balance, and energy balance calculations, this study examines the global warming, acidification, and eutrophication potential using the openLCA v1.10.3 software and Environmental Footprint (MID-Point indicator) database for impacts assessment when the system is operated in Indonesia and Malaysia with various electricity sources. It is found that the feedstock contributed most of the global warming potential and eutrophication potential, while the electricity dominated the acidification potential. This study recommends operation at a lower equivalent ratio to reduce environmental impacts.     

Investigation on the durability of direct dimethyl ether fuel cell. Part II: Cathode degradation

Cathodic Pt/C catalyst degradation for a direct dimethyl ether fuel cell (DDFC) has been investigated after a 70.5 h galvostatic operation at 60 °C under ambient pressure. The cathode electrochemical active surface (EAS) reduces from 349 to 267 cm² mg^?1 Pt after durability test. Cathode EAS loss is associated with the growth of Pt catalyst particles. XRD and TEM results show that the particle size of cathodic Pt catalyst increases from an original value of 3.0 nm to 5.4 nm. Furthermore, the anode failure accelerates dimethyl ether (DME) crossover, and consequently, poisoning of catalyst by absorbed DME and/or intermediates aggravates the degradation of cathodic Pt/C catalyst. The effect of anode degradation on the long-term performance of DDFC has been reported in companion article (Part I).     

Life cycle costing of diesel,natural gas,hybrid and hydrogen fuel cell bus systems: An Australian case study

The transit authority in Perth, Western Australia, has put several alternative fuel buses, including diesel-electric hybrid and hydrogen fuel cell buses, into revenue service over the years alongside conventional diesel and natural gas buses. Primary data from this fleet is used to construct a Life Cycle Cost (LCC) model, providing an empirical LCC result. The model is then used to forecast possible scenarios using cost estimates for next generation technologies. The methodology follows the Australian/New Zealand Standard for Life Cycle Costing, AS/NZS 4536:1999. The model outputs a dollar value in real terms that represents the LCC of each bus transportation technology. The study finds that Diesel buses deliver the lowest Total Cost of Ownership (TCO). The diesel-electric hybrid bus was found to have a TCO that is about 10% higher than conventional diesel. The premium to implement and operate a hydrogen bus, even if industry targets are attained, is still substantially greater than the TCO of a conventional diesel bus, unless a very large increase in the diesel fuel price occurs. However, the hybrid and hydrogen technologies are still very young in comparison to diesel and economies of scale are yet to be realised.     

Life cycle assessment of hydrogen fuel cell and gasoline vehicles

A life cycle assessment of hydrogen and gasoline vehicles, including fuel production and utilization in vehicles powered by fuel cells and internal combustion engines, is conducted to evaluate and compare their efficiencies and environmental impacts. Fossil fuel and renewable technologies are investigated, and the assessment is divided into various stages.