柴油替代燃料二甲醚的应用开发和发展概况

详细介绍了二甲醚作为柴油替代燃料的开发和应用情况。以天然气为原料制二甲醚，天然气价格对产品成本影响非常大，目前二甲醚作为柴油替代燃料还不具备和柴油竞争的优势，相比之下合成气一步法工艺技术更具有竞争优势。概述了我国二甲醚发展现状，并对我国二甲醚发展提出了建议。     

二甲醚合成技术进展及应用开发

综述了甲醇脱水制二甲醚、合成气一步法合成二甲醚的技术进展 ;分析了二甲醚在民用洁净燃料、替代柴油燃料等领域的应用前景     

绿色燃料-二甲醚

本文介绍了二甲醚代替柴油作为燃料的发展,以及二甲醚的性质。     

二甲醚的生产与市场需求

介绍了用煤炭或天然气生产二甲醚的生产工艺和生产应用,论述了二甲醚的主要用途和我国燃料市场的需求,总结了用二甲醚洁净燃料替代柴油对我国能源结构调整的重要性。     

二甲醚的燃料特性与生产方法

论述了二甲醚替代石油液化气,替代柴油的燃料特性;从燃料毒性、燃料替代对象、适用发动机、尾气中甲醛含量等方面对比了甲醇燃料和二甲醚燃料的共同特点和不同优势;介绍了四川天一科技股份有限公司开发的甲醇气相法生产二甲醚的工艺特点、设备优势和生产应用情况.     

二甲醚的生产现状及发展前景

二甲醚是我国值得重点发展的清洁燃料,文章分析了二甲醚代替柴油作为汽车燃料、代替民用液化石油气的可行性,并对二甲醚的生产工艺如两步法、一步法、二氧化碳及生物质直接合成二甲醚等进行评述,认为一步法工艺比较适合我国国情,适用于化肥厂和甲醇厂生产二甲醚。     

二甲醚的用途及发展前景

介绍了二甲醚（DME）的用途及发展前景，阐述了二甲醚用作柴油替代燃料的潜在优势。     

二甲醚(DME)应用前景瞻望

二甲醚(DME)是近几年被广泛看好的柴油及液化气替代燃料,文章论述了DME的用途及前景用途,阐述了二甲醚用作替代燃料的潜在优势。     

二甲醚应用前景瞻望

二甲醚（DME）是近几年被广泛看好的柴油及液化气替代燃料,本文论述了DME的用途及应用前景,主要阐述了二甲醚用作替代燃料的潜在优势。     

新型清洁燃料——二甲醚的开发和发展前景

二甲醚是清洁而良好的柴油替代燃料，本文介绍了二甲醚的性质和用途，合成技术以及发展动向。     

Experimental and analytical study on the spray characteristics of dimethyl ether (DME) and diesel fuels within a common-rail injection system in a diesel engine

This paper investigates the effect of injection parameters on the characteristics of dimethyl ether (DME) as an alternative fuel in a diesel engine with experimental and analytical models based on empirical equations. In order to study macroscopic and microscopic characteristics of DME fuel, this work focuses on the atomization characteristics of DME and compares experimental and predicted results for spray development obtained by empirical models for diesel and DME fuel. Detailed comparisons of spray tip penetration from three different empirical correlations and from visualization experiments of diesel and DME fuels were conducted under various fuel injection conditions. In comparison with the results of different empirical equations for measured spray tip penetration, the experimental results of this study provide good agreement with the calculation results based on empirical equations, except during the earliest stage of the injected spray sequence. The results of atomization characteristics indicate that DME showed better spray characteristics than conventional diesel fuel. Also, the fuel injection delay and maximum injection rate of DME fuel are shorter and lower than those of diesel fuel at the same injection conditions, respectively.     

Pilot ignited premixed combustion of dimethyl ether in a turbodiesel engine

This paper describes combustion studies of dimethyl ether in a common rail turbodiesel engine wherein the dimethyl ether was fumigated into the intake air and the conventional diesel injection was used with the intention of igniting the premixed DME-air charge. This combustion process is referred to here as a “mixed mode” process and is similar in some respects to what is commonly referred to as “dual fuel” combustion. In contrast to “dual fuel” combustion, however, in which the gaseous fuel is often natural gas or biogas, in this process with DME the gaseous charge ignites largely independently of the diesel injection. The diesel injection was accomplished with a single, main injection. The engine was operated at a single speed and load. Gaseous and particulate emissions were monitored and heat release analysis was performed to examine how the fuels burn and the impact on emissions formation at various levels of substitution of diesel fuel with fumigated DME, at as high as 44% of the fuel energy from DME. Reductions in NO_x emissions and increases in particulate matter emissions are observed with DME fumigation. The increase in PM emissions is attributed to enrichment of the diesel fuel spray, due to displacement of intake oxygen by the fumigated DME, despite the widely observed soot suppressing effect of DME.     

The potential of di-methyl ether (DME) as an alternative fuel for compression-ignition engines: A review

This paper reviews the properties and application of di-methyl ether (DME) as a candidate fuel for compression-ignition engines. DME is produced by the conversion of various feedstock such as natural gas, coal, oil residues and bio-mass. To determine the technical feasibility of DME, the review compares its key properties with those of diesel fuel that are relevant to this application. DME’s diesel engine-compatible properties are its high cetane number and low auto-ignition temperature. In addition, its simple chemical structure and high oxygen content result in soot-free combustion in engines. Fuel injection of DME can be achieved through both conventional mechanical and current common-rail systems but requires slight modification of the standard system to prevent corrosion and overcome low lubricity. The spray characteristics of DME enable its application to compression-ignition engines despite some differences in its properties such as easier evaporation and lower density. Overall, the low particulate matter production of DME provides adequate justification for its consideration as a candidate fuel in compression-ignition engines. Recent research and development shows comparable output performance to a diesel fuel led engine but with lower particulate emissions. NO_x emissions from DME-fuelled engines can meet future regulations with high exhaust gas recirculation in combination with a lean NO_x trap. Although more development work has focused on medium or heavy-duty engines, this paper provides a comprehensive review of the technical feasibility of DME as a candidate fuel for environmentally-friendly compression-ignition engines independent of size or application.     

Investigation on the fuel spray and emission reduction characteristics for dimethyl ether (DME) fueled multi-cylinder diesel engine with common-rail injection system

The aim of this study is to investigate the effects of dimethyl ether (DME) fuel on the engine performance and the exhaust emission reduction characteristics in a DME fueled four-cylinder diesel engine with a common rail injection system, as well as an injection characteristics and a spray behavior. The injection rate meter and the spray visualization system are utilized for the analysis of the injection characteristics and the spray behavior. Also, the modified four-cylinder diesel engine with 1.6 liter engine size is used for the investigation of the engine performance and the exhaust emission reduction characteristics of DME fuel.Based on the experimental investigation, it revealed that the injection quantity of DME fuel was larger than that of the ultra low sulfur diesel (ULSD) due to the high return fuel pressure at the same injection pressure and energizing duration. In this case, the injection quantity of DME fuel is increased by extension of real injection duration due to return fuel pressure.In combustion characteristics, the peak combustion pressure and the ignition delay of DME fuel are higher and faster than those of ULSD, respectively. The NO_x emission of DME fuel shows slightly higher than that of ULSD at the same engine load condition, and the soot emission of DME fuel is nearly zero level. The oxygenated component and volatility of DME resulted in HC and CO emissions that were lower than those of diesel.     

Critical solubility of dimethyl ether (DME)+diesel fuel and dimethyl carbonate (DMC)+diesel fuel

An experimental apparatus was developed for measuring the critical solubility. The critical solubilities were determined for binary mixtures of DME+diesel fuel and DMC+diesel fuel. For DME+diesel fuel their critical solubility temperatures ranged from 272.83 to 255.13 K while the mass fractions of DME varied from 3.44 to 95.8%; For DMC+diesel fuel, their critical solubility temperatures were between 273.58 and 302.72 K while the mass fractions of DMC varied from 1.22 to 89.6%.     

Study on the application of DME/diesel blends in a diesel engine

In this paper fuels, based on various DME to diesel ratios are investigated. Physical and chemical properties of DME and diesel display mutual solubility at any ratio. The vapor pressure of DME/diesel blends is lower than that of pure DME at the same temperatures and it decreases with an increase of diesel mass fraction in blends, which is beneficial to the elimination of vapor lock in the fuel supply system on CI engines. Performance, emission and other features of three kinds of DME/diesel blend fuels and diesels are evaluated in a four-cylinder test engine. By taking relative advantages of DME and diesel, the DME/diesel blends could achieve satisfactory properties in lubricity and atomization, which contributed to improvements in spray and combustion characteristics. Simultaneously, smoke emission could be reduced significantly with a little penalty on CO and HC emissions for DME/diesel blended engine at high loads, in comparison to diesel engine. NO_x emissions of the engine powered by DME/diesel blends are decreased somewhat. Moreover, the power output would be improved a little and NO_x emission could be reduced further if the fuel supply advance angle is retarded appropriately.     

Study of fuel consumption when introducing DME or ethanol into diesel engine

An investigation of the effect of DME or ethanol on fuel consumption is conducted in a four-stroke, one-cylinder, direct-injection diesel engine. DME or ethanol is first heated to pyrolyze and then the resultant product gas is introduced into air intake. Brake Specific Fuel Consumption (BSFC) can be reduced a lot, when emulsified fuel (diesel fuel emulsified with water) is fueled to diesel engine and DME is heated to about 1000 K before its being introduced into air intake. Results show that BSFC can be decreased by about 10% and diesel fuel consumption can be decreased by 18%. High saving rate of BSFC up to 10% is also acquired using ethanol instead of DME. To achieve high saving rate of BSFC, the heating temperature of about 1000 K is needed for DME operation, while the diesel engine exhaust temperature of about 750 K is enough for pyrolyzing ethanol. Hydrogen produced in DME or ethanol pyrolysis is considered as the main reason for the excellent fuel saving. The technique adopted in the present work is extremely easy to utilize, and may be firstly adopted on diesel engines for power plants, trains, ships, etc.     

Combustion and emission characteristics of DME as an alternative fuel for compression ignition engines with a high pressure injection system

The subject of this work is the investigation of the injection characteristics of neat dimethyl ether (DME) and the effect of DME fuel on the exhaust emission characteristics and engine performance of compression ignition engines. In order to analyze the injection characteristics of DME fuel as an alternative fuel for compression ignition engines, experiments were conducted to obtain the injection rate profile. The effective nozzle diameter and its velocity, and the discharge coefficient of the nozzle were analyzed by applying a nozzle flow model that accounted for the effect of cavitation. In addition, combustion characteristics of DME and diesel fuel in terms of combustion pressure, rate of heat release, indicated mean effective pressure (IMEP), and ignition delay at various injection timings were investigated on a constant energy input basis.When a constant pulse width was applied, the results of DME injection characterization showed that the actual injection duration of DME was longer than that of diesel fuel because the injection started faster and ended with more delay. The DME fueled engine showed slightly higher IMEP and NO_x emission with drastically lower CO and HC emissions and the possible reasons for the higher IMEP of DME fuel was discussed.     

A novel synthesis of diesel fuel additives from dimethyl ether using dielectric barrier discharges

A diesel fuel additive has been synthesized from conversion of dimethyl ether (DME) using dielectric barrier discharge (DBD) plasma at atmospheric pressure and low temperatures. A high conversion of DME has been achieved. The product of such conversion is a mixture of hydrocarbons and oxygenates that can be used as high-performance diesel fuel additives. The maximum conversion of DME reached 47.2% with a selectivity of liquid product (a mixture of dimethoxy-containing hydrocarbons) more than 39.0% at 120°C and a 30 ml/min flow rate of DME.     

Macroscopic spray characteristics and breakup performance of dimethyl ether (DME) fuel at high fuel temperatures and ambient conditions

The purpose of this work was to investigate, both experimentally and numerically, the spray behavior and atomization characteristics of dimethyl ether (DME) at high fuel temperatures and under various ambient conditions. In order to compare the theoretical and measured spray characteristics of DME fuel, macroscopic characteristics such as spray tip penetration and spray cone angle were investigated using spray visualization system with a heating system. DME atomization performance was calculated under various conditions from KIVA-3 V code and studied via analysis of the overall Sauter mean diameter (SMD) map, which is related to ambient gas temperature, ambient pressure, and fuel temperature.DME spray was found to exhibit behavior that differs from diesel spray under atmospheric condition. However, at high ambient pressure conditions, DME and diesel sprays display similar behavior. At ambient atmospheric condition, the spray cone angle of DME fuel is larger than that of diesel spray due to the occurrence of flash boiling. Variation in DME fuel temperature had little effect on spray tip penetration and spray cone angle characteristics. An increase in ambient air temperature caused an increase in DME spray cone angle due to an enhancement of the flash boiling effect. However, the DME spray cone angle showed a decreasing trend at high ambient pressure conditions when the ambient air temperature was increased. This was due to the disappearance of flash boiling and the evaporation of droplets at the exterior of the spray cone. In the overall SMD map, the increase of the ambient gas temperature and fuel temperature induced the increase of DME overall droplet size. On the other hand, the ambient gas pressure have slightly influenced on the overall SMD at a low ambient gas temperature and low fuel temperature, but the effect of the ambient gas pressure is significant at high ambient gas temperature and high fuel temperature. At high ambient gas temperature, the increase of the ambient gas pressure causes the increase of the overall SMD. At high DME fuel temperature, the decrease of the ambient gas pressure induces the increase of the overall SMD.