【作者】 周少任；

【导师】 张煜盛；

【作者基本信息】 华中科技大学 ， 动力机械及工程， 2007， 硕士

【摘要】 面临能源危机和环境污染的双重挑战,内燃机的高效清洁燃烧已经在各国内燃机界引起了广泛的关注。二甲醚（DME）因其突出的理化特性及超低排放被认为是清洁高效的车用发动机燃料,近年来国内外开展了大量的二甲醚燃烧性能和排放的实验与模拟研究。本文首先就内燃机代用燃料的发展以及二甲醚的理化特性与在发动机上的应用,EGR技术的发展进行了简要的介绍。然后对DME发动机燃烧的非常规排放物进行了变参数试验研究,得到了限制非常规排放物的试验条件与发动机运行参数。探讨了非常规排放物的反应机理及非常规排放物与常规排放物（甲醛与HC排放、甲酸与NO排放）之间的关系。建立了进气掺混CO₂的DME发动机试验台架,自行设计了台架的进气系统,校准了瑞士生产的高精度Kistler压电传感器同与之配套的电荷放大器,设置了测量非常规排放物的傅立叶变换红外分析仪的CALCMET检测库。在燃烧性能与排放的试验中,测量了CO₂添加后,DME发动机的缸内压力、压力升高率及压力升高加速度,油耗率、排气温度、噪声、过量空气系数,排气中的常规排放物CO、CO₂、O₂、HC与NOx,以及非常规排放物甲醛,甲酸与甲酸甲酯的浓度。为进一步深入的理论计算提供了大量的实验数据。采用watson零维模型就进气添加CO₂对DME发动机燃烧特性参数（如缸内温度,比热比等）与性能参数（如缸内压力）的影响进行了数值模拟与试验验证,证实了watson模型及其计算程序的有效性。同时。利用实测的发动机示功图,进行了DME发动机燃烧放热率的计算与参数分析研究。在watson零维模型的基础上,采用准维多区模型对DME发动机NOx的排放进行数值模拟,探讨了其随CO₂掺混量变化而变化的规律,并且通过试验数据验证了该模型的适用性和良好的预测能力。更多还原

【Abstract】 Facing the double challenges of energy crisis and enviriomental pollution, the hight efficient and clean combustion of internal combustion engine （ICE） were more and more concerned world widely. The excellent physical - chemical characteristics and ultra low emission of DME （Dimethyl Ether） made it as a clean and high efficient alternative fuel of automotive. A great many of experimental and numerical research on the combustion and emission of DME were carried out around the world during recent years.The development of alternative fuels, physical-chemical characteristics of DME and its application on ICE and the EGR （Exhaust Gas Recirculation） were introduced firstly in this paper. The suitable parameters of the test engine for DME are obtained from the experimental study of variable parameters of DME engine. The relationships between regular and un-regulated emissions of DME engine were discussed in this paper.The experimental setups of the effect of CO₂ addition in intake air on combustion and unregulated emissions of DME engine were established. The design of intake air system and the calibration of high precision Kistler pressure sensor with the supporting charge amplifier and the establishment of library of CALCMET of FTIR （Fourier Transform Infrared Spectroscopy） which used for the detection of the unregulated emissions were accomplished by the author. The in-cylinder pressure, the rate of pressure rise and the acceleration of pressure rise, the rate of DME consumption ,emission temperature, noise, excess, air coefficient, the concentrations of CO, CO₂, O₂, HCand NOx, HCHO（fomaldehyde）, HCOOH（formic acid） and CH3OCHO（methyl formate） were also measured during the experiment. These datas could be used for the further numericial studys.Based on the experimental studys, the in-cylinder temperature and specific heat ratio and the in-cylinder pressure were calculated by watson zero dimentional model. The effectiveness of WATSON zero dimentional model was verified. Meanwhile, the heat release ratio was calculated by using the experience formulas on the basis of p-φpictures which were got from the experiments.The NOx emissions of DME engine were simulated by the quasi-dimentional multi-zone model.and the law of NOx emission diminished as the quantity of addition CO₂ increased was testified. In conclusion, the quasi-dimentional multi-zone model was predictable and useful.更多还原