Simulation Research On Dimethyl Ether/iesel Dual-fuel Fuel Supply System

Compared with diesel,dimethyl ether(DME)is an efficient,low-pollution and economic fuel for engine.Faced with an increasingly serious energy and environmental issues,dimethyl ether has the potential to be the alternative fuel of diesel engine.However,due to the saturation vapor pressure of dimethyl ether is much higher than diesel,gasification phenomenon take place in the fuel supply system especially in the fuel injection pump easily,which will lead to fuel variation per cycle and affect the normal work of the diesel engine.Therefore,the vaporization of fuel supply system seriously hampered the promotion and application of dimethyl ether as an alternative fuel for diesel engines.On account of gas block phenomenon in fuel supply system,the author’s team put forward a technical solution of three-way check valve,which is economy,simple and efficient.In this paper,studying on traditional fuel supply system of 2-135 diesel engine’s injection pump-tube – nozzle produced by Shanghai Diesel Engine Factory,Using AVL-hydsim simulation software platform to build prototype fuel supply system model、traditional dimethyl ether / diesel dual fuel oil supply model and the model of dimethyl ether / diesel dual fuel oil supply whit three-way check valve.By comparing the prototype fuel system and the traditional dimethyl ether/diesel dual fuel system,analyzed of the influence of various parameters on gasification phenomenon in the injection pump chamber,and demonstrated of the traditional dimethyl ether/diesel dual fuel oil supply system will inevitably appear gasification phenomenon.For three-way check valve solution,using the simulation method,(1)research and analysis the influence of compressibility of the mixed fuel on spray characteristics,the conclusion is as follows,1 since the three-way check valve changed the structure so that the fuel pump chamber volume increases,leading to the pump chamber pressure and injection quantity per cycle decreased;2 With the increase of mass fraction of dimethyl ether in mixed fuel,the elastic modulus of mixed fuel decreases,but compressibility increases,what’s more,the pressure of pump chamber and injection pipe will decline,fluctuations of residual pressure in the injection pipe increases,but multiple injections never happened,and the injection rate of fuel supply system will increase,the amount of fuel injection per cycle will decrease.At the same time,by using the simulation method,the author assistsed our test team to complete the design of the three-way check valve and to draw up a plan of experimental research programs,and here’s the effect:(2)1 The diameter of the sealing surface,compared to the gap length of sealing surface,has a greater impact on dimethyl ether/diesel dual fuel oil supply system’s leakage.With the increase of leakage in the system,the pressure of pump chamber and fuel injection quantity per cycle will decrease;2 Response speed of check valve does not affect the maximum pressure in the pump chamber,but the stiffness of check valve spring is greater,the response speed is slower,and the pressure fluctuations of pump chamber 、the lift of check valve and fuel injection quantity per cycle is smaller as well.