【作者】 田维；

【导师】 魏远文； 黄海波；

【作者基本信息】 西华大学 ， 动力机械及工程， 2007， 硕士

【摘要】 二甲醚(DME)是一种新型的、清洁的柴油机代用燃料，可以达到美国加州超低排放车辆标准(ULEV)。在柴油机上燃用二甲醚，从长远来看可以缓解能源危机，从近来看则可以改善汽车排气污染。目前，二甲醚在柴油机上应用还处于研究阶段。二甲醚的十六烷值高、蒸发潜热大、分子结构中没有C-C键、雾化质量好等特点决定了它是目前柴油最优良的替代燃料；但是它的粘度值低、弹性模量小、分子小、饱和蒸汽压力大、液态密度小等性质对传统柴油机供给系统提出了新的挑战，影响了其良好发展势头。本文针对二甲醚在柴油机上燃用的不宜条件进行了详细研究，借助AMEsim仿真软件，设计出了适合于二甲醚发动机的燃料供给系统并进行了验证。AMEsim是目前国际上比较先进的液压系统仿真软件。借助该软件，本文建立了二甲醚发动机燃料供给系统的AMEsim模型，其中主要包括油泵模型、出油阀模型和喷油器模型。以ZS1100为样机模型进行适当的参数设置，对原柴油机燃用柴油的情况进行了计算机仿真，结果良好。再用原机参数进行了原机燃用二甲醚情况下的仿真，从结果中发现：原机未经改动情况下直接燃用二甲醚时，其供油量不足、泄漏大大增加、最高喷射压力下降、喷油延迟增加、喷油量下降、高压油管剩余压力变高，完全不能满足二甲醚对燃料供给系统的要求，必须进行改进。本文根据二甲醚的性质，以恢复原机动力性为原则进行了参数和系统结构的调整。仿真结果表明，为了恢复原机动力性能必须调整柱塞直径(加大供油量)、出油阀尺寸、油管直径、喷油孔直径、针阀升程限位等结构参数。本文利用AMEsim强大的批处理功能，对二甲醚发动机供给系统进行了变参数仿真研究。变参数研究主要是针对影响比较大的参数：启喷压力、喷油孔直径、喷油孔数、发动机转速。仿真结果表明：启喷压力会影响喷油持续时间、最高喷射压力、二次喷射、喷油量等，喷孔会影响喷油量、最高喷射压力针阀升程等，转速主要是影响了喷油延时。上述研究结论为进一步研究二甲醚发动机提供了方向性指导。更多还原

【Abstract】 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.更多还原