Experimental Study About Blended Combustion Of Dimethyl Ether With Diesel

As the basis of survive and continual development, source and environment already aroused the attention of human being. The shortage of energy sources and the protection of environment are the two main topics that the development of global economy faces about.With the developing of national economy and the increasing of automobile quality, the shortage of petrol is becoming more and more severe, and the emission of exhaust gas from internal combustion engine becomes one of chief source of pollution in the large cities. As a rising regenerated sanitary fuel, Dimethyl Ether (DME) has gained the attention of the entire world. The IEA/AMF(International Energy Agency, Implementing Agreement: Alternative Motor Fuels ), a allied research community about Dimethyl Ether, has been established. There are ten government department, researching institution and companies who attend this researching project. These member included Austrian AVL-List institution ,Canadian AET and NR Canada, Danish Haldor Topsf e A/S company and technique university, Finland, French Renault, PAS and IFP, Japan, Netherlandish Innas B, Akzo Nobel and TNO researching institution about road of automobile;Norway Statoil;Sweden Atrax Energi AB and Volvo Truck;American Amoco Corporation and AVL Power train Engineering. By the effort in several years, the member of the IEA/AMF accomplished the research effort about the feasibility of the DME as one automobile fuel. At present, the research about DME fuel has enter applied stage in many country.Aimed at the characteristic of energy in our country, it has great strategic significance to develop the alternative fuel of DME that can be draw out from coal, nature gas, coal gas stratum and nature matter, shape the alternative fuel system of the diesel engine that adopt to the situation of our country for alerting the energy structure of our country and decreasing the dependent on the petrol and ensuring the energysafety of our country. It is one of the effective ways that extend the apply of the new DME fuel to alter the nervous situation of producing energy and consumption.If the DME were directly mixed with diesel as the fuel of the diesel engine, there will be some problem, such as the need of keeping high pressure in fuel supply system because of gasify the DME and the difficulty to nicely control spray mass in high load because of the high temperature of oil pump when the diesel work that lead the gasification of the DME and brought air bubble in low pressure of oil pipe in oil pump, all these problem will make the engine work unsteadiness. Now the special spraying pump of the DME is not mature, so in this paper we took a new technical scheme that the pure DME or mixed DME who form mixed gas with air getting in from the intake pipe of the diesel engine entered the combustion chamber and burn with the diesel of spraying combustion chamber later.Under the conditions that we did not change the configuration of the diesel engine, by adding a fuel system of DME, we can make the pure DME or mixed DME form mixed gas with air that get in from the intake pipe of the diesel engine, and this mixed gas enters the combustion chamber and burns with the diesel which are sprayed* it into combustion chamber later. The influence of the blends combustion of the mixed DME fuel to combustion process and emission in cylinder are researched. The results are as follows.1- The influence about the blends ratio of pure DME in JIED diesel engine and ignition depressor in mixed DME to combustion process and emission of engine is researched. The conclusions are as follows:(1) When the pure DME burn with diesel, with the increase of substitute ratio of torque, pre-ignition is obvious and the start of ignition is advanced. MttothE ksnraasBitm of content of the DME in mixed mass, the maximum of combustion pressiMteaccreteiec;When substitute ratio of torque diminishes, the maximum of combustion rate of heatrelease and the maximum of pressure rise rate decrease and the work process of engine will be more stable. But when the substitute ratio of torque exceeds 20%, the maximum of pressure rise rate increase and the work process of engine will be violent because of the advance of the start of ignition of the DME, so we needed ignition depressor to control the start of ignition.(2) When pure DME burn with diesel, with the increase of substitute ratio of torque, the emission of NOx is decreased gradually, the emissions of CO and smoke are increased and the emission of HC is trivial increased.(3)When mixed DME burn with diesel, with the increase of ignition depressor ratio, it has obvious action to restrain the start of ignition. When the ratio of ignition depressor is 40%, the start of ignition of blended combustion is close to the start of ignition of diesel.(4) When mixed DME burn with diesel, with the increase of ignition depressor ??â– >â–  ratio, the emission of NOx is trivial increased, the emission of HC and smoke are equivalent with pure DME burning with diesel, the emission of CO istrivial decreased.2- The optimized experimentation that mixed DME L30 and the diesel in JIEDA diesel engine are blended and burn is carried out. With the changing of mixed DME heat ratio in all combustion process in vary speed and road, we researched combustion and emission characteristic changing trend, and selected befitting DME heat ratio. We compared changing trend of the emission and economic characteristic after the optimization of mixed firingL30 and diesel. The conclusions are as follows:(l)With the decrease of mixed DME heat ratio, the emission of NOx is decreased, the emission of CO and HC are increased, the emission of smoke is trivial increased.(2) From the contrast of engine emission after optimization, the emission of NOx is decreased, the emission of CO and HC are increased, especially in low road. It isobvious that the emission of smoke is increased in high road. The effective heat of the entire engine has little change in the field of economical efficiency.