Design Of DME Engine Fuel Injection System

Dimethyl ether (DME) is one kind of newly appearance and clean alternative fuels for diesel engine. The DME engine can achieve California ultra low emission vehicle standard. In long run, DME used on diesel engine can slow down the energy crisis and in short sight it can ameliorate the vehicle exhaust emission. At present, the universal use of DME on diesel engine is in process.The cetane value and heat of evaporation of DME is larger than diesel oil, the spray is better, and is not contain C-C bond in DME molecule, so that DME is the best alternative fuel of diesel oil. At the same time, its viscidity, liquid state density and elasticity module is small, but saturation vapor pressure is large. Those disadvantages listed in front challenge the traditional injection system of diesel engine and block the development process. This dissertation study those disadvantage and design suitable supply system for DME engine under the help of AMEsim, and use experimentation to validate it.AMEsim is the best advanced hydraulic system simulation software in the world. This dissertation use it to set up the DME engine injection system model include pump model, delivery valve model and injector model and simulate the situation of ZS1100 burning diesel oil and burning DME separately, the result is right and indicate that the original engine system is not suitable for DME. So we change the piston diameter, delivery valve dimension, pipe diameter, spray holes diameter and poppet lift etc. to meet the power capability requirement.The dissertation use the batch disposal function to investigate the behavior of the injection system when change the parameter, such as open pressure, hole diameter and engine speed, of it. The result shows that the open pressure influences the injection duration time, highest spray pressure, injection quantity etc, the diameter influences the injection quantity and poppet lift etc, and the engine speed influences the injection delay. Those results can be the guide for later research.