Research On The Effect Of CO₂ Addition In Intake Air On Combustion And Unregulated Exhaust Emissions Of CI Engine Operated With Dimethyl Ether

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.