二甲醚替代石油液化气的可行性研究

二甲醚作为新型清洁能源,不仅可以解决我国油气短缺的问题,而且燃烧后的烟气中不含有对大气环境有污染的SO2等.本文对二甲醚替代石油液化气的可行性进行了研究.根据燃气互换性原理,将石油液化气燃具改造成适合二甲醚燃烧的燃具,并对燃烧效果进行了测试分析.结果表明,烧开相同质量、温度的水,二甲醚燃具所需时间及燃料消耗量均低于石油液化气燃具;另外在单位时间内,二甲醚的消耗量略高于石油液化气的消耗量,表明二甲醚燃烧速度比石油液化气高.二甲醚作为清洁能源,在燃烧温度、单位燃烧时间消耗量等方面都优于石油液化气.为二甲醚作为工业清洁能源提供了新思路和基础.     

二甲醚-柴油混合燃料性质的实验研究

对二甲醚-柴油混合燃料影响发动机性能的稳定性、黏度这两种理化性质进行了研究。通过对不同比例混合燃料的互溶性、黏度等理化性质的测试和研究，得出了在二甲醚中掺加柴油不仅能使两种燃料混合均匀、稳定性好，而且可以有效提高燃料的黏度，降低发动机精密偶件的磨损，提高发动机的工作可靠性。     

合成气一步法合成二甲醚研究

结合国内外二甲醚研究现状,从合成气一步法合成二甲醚的分类、工艺、热力学、动力学、催化剂等方面进行了阐述,并对合成气一步法制取二甲醚进行了技术评价。     

Homogeneous charge compression ignition of LPG and gasoline using variable valve timing in an engine

The combustion characteristics and exhaust emissions in an engine were investigated under homogeneous charge compression ignition (HCCI) operation fueled with liquefied petroleum gas (LPG) and gasoline with regard to variable valve timing (VVT) and the addition of di-methyl ether (DME). LPG is a low carbon, high octane number fuel. These two features lead to lower carbon dioxide (CO₂) emission and later combustion in an LPG HCCI engine as compared to a gasoline HCCI engine. To investigate the advantages and disadvantages of the LPG HCCI engine, experimental results for the LPG HCCI engine are compared with those for the gasoline HCCI engine. LPG was injected at an intake port as the main fuel in a liquid phase using a liquefied injection system, while a small amount of DME was also injected directly into the cylinder during the intake stroke as an ignition promoter. Different intake valve timings and fuel injection amount were tested in order to identify their effects on exhaust emissions and combustion characteristics. Combustion pressure, heat release rate, and indicated mean effective pressure (IMEP) were investigated to characterize the combustion performance. The optimal intake valve open (IVO) timing for the maximum IMEP was retarded as the λ_TOTAL was decreased. The start of combustion was affected by the IVO timing and the mixture strength (λ_TOTAL) due to the volumetric efficiency and latent heat of vaporization. At rich operating conditions, the θ_90-20 of the LPG HCCI engine was longer than that of the gasoline HCCI engine. Hydrocarbon (HC) and carbon monoxide (CO) emissions were increased as the IVO timing was retarded. However, CO₂ was decreased as the IVO timing was retarded. CO₂ emission of the LPG HCCI engine was lower than that of the gasoline HCCI engine. However, CO and HC emissions of the LPG HCCI engine were higher than those of the gasoline HCCI engine.     

空调制冷剂R1270/R227ea/DME的热力学性能分析

针对制冷剂R22的替代问题,提出了一种适用于家用空调的环保型混合制冷剂R1270/R227ea/DME。在Refprop 8.0基础上,对R1270/R227ea/DME的基本热物理性质和制冷系统热力学性能进行了分析,结果表明:在标准的空调工况下,R1270/R227ea/DME混合制冷剂的COP和单位容积制冷量均与R22相当,非常有利于直接充灌替代;R1270/R227ea/DME的滑移温度和GWP值均很小,性能也优于R407C,是一种优良的R22替代物。     

合成气液相一步法制备二甲醚

介绍了二甲醚的液相合成气一步法制备工艺及其应用。     

二甲醚发动机低压共轨燃料喷射系统的设计及试验

针对二甲醚燃料低粘性、高蒸汽压以及容易与空气形成混合气的特性,设计了一种可控预混合燃烧的二甲醚发动机低压共轨电控燃油喷射系统.在此基础上,以柴油代替二甲醚进行试验,分析了在喷射持续期,共轨压力、针阀升程和转速对燃油喷射过程的影响,得出了低压共轨燃料系统的燃料喷射特性,对二甲醚低压共轨系统的实用化起到了促进作用.     

代用燃烧DME及其研究进展

由于DMF（二甲基醚）有良好的压燃着火性能以及不需特别的措施就能达到超低排放标准，因而成为柴油发动机一种很有潜力的替代燃料，多年来各国对DME作为柴油的代用燃料作了大量的研究，对DME的喷雾过程，自燃着火过程和燃烧过程等方面有了较为深入的了解，在此基础上发展了专为DME使用的电控喷射系统。     

The viscosity of dimethyl ether

Dimethyl ether (DME) has been recognised as an excellent fuel for diesel engines for over one decade now. Engines fuelled by DME emit virtually no particulate matter even at low NO_x levels. This is only possible in the case of diesel oil operation if expensive and efficient lowering particles and NO_x traps are installed.The most significant problem encountered when engines are fuelled with DME is that the injection equipment breaks down prematurely due to extensive wear. This tribology issue can be explained by the very low lubricity and viscosity of DME. Recently, laboratory methods have appeared capable of measuring these properties of DME. The development of this is rendered difficult because DME has to be pressurised to remain in the liquid state and it dissolves most of the commercially available elastomers.This paper deals fundamentally with the measurement of the viscosity of DME and extends the discussion to the difficulty of viscosity establishing of very thin fluids. The main issue here is that it is not easy to calibrate the viscometers in the very low viscosity range corresponding to about one-fifth of that of water. The result is that the low viscosity is measured at high Reynolds numbers so that the outcome has to be corrected by various factors. The validity of these can be discussed especially when they exceed a few percent of the apparent viscosity.The volatile fuel viscometer (VFVM) developed at DTU is presented. By enclosing a standard glass capillary viscometer in a glass tube it is possible to measure the viscosity of fluids at pressures below 15 bars. The kinematic viscosity of DME was established at 0.184 cSt @ 25 °C at the vapour pressure of the fluid at that temperature. The measurements were made at reasonable Reynolds numbers so the correction factors are negligible indicating a high accuracy of the method.Other pressurised viscometers have appeared since the development of the VFVM. These predict a 5–19% higher viscosity for DME than the VFVM. It seems that the causes for these differences are a too high Reynolds number and/or an influence of the gas used for pressurisation in these methods. The results of the VFVM are consolidated by measurements of the viscosities of propane and butane: these agree with the outcome of measurements using a quartz crystal microbalance (QCM) a method that is supposedly less sensible than the Reynolds number.