二甲基醚发动机HCCI燃烧与排放的计算

构建了可应用于均质充量压燃（HCCI）发动机的二甲基醚（DME）详细化学反应动力学M燃烧模型，该模型包含97种物种和457个基元反应．拓展M模型的应用范围，分析了DME发动机HCCI条件下关键基元反应和重要物种随曲轴转角的变化关系，获得了DME氧化反应的主要历程．研究了NOx的生成机理，结果表明NOx排放中NO生成量达到最大值后出现“冻结”现象，NO2与N2O最终排放浓度极少且受缸内温度影响不大．随着缸内温度的增加，NOx排放中NO所占比例逐渐增加．基于化学反应速率及敏感度分析，得到了DME发动机HCCI燃烧的NO排放主要受扩大Zeldovich机理和N2O途径控制．

Calculation of combustion and emission from HCCI engine fuelled with dimethyl ether

A new detail chemical kinetic model of dimethyl ether(DME),combustion model M,consisting of 97 species and 457 key reactions,was built to study the combustion of and emission from homogeneous charge compression ignition(HCCI) engine.The application area of the new model was extended.The change relationship with the crank angles between the key reactions and important species under HCCI was studied.The main courses of DME combustion and formation mechanism of NO_x were studied.The results show that the amount of NO in the exhaust of NO_x changes less after the maxim concentration of NO reaches.The emission amount of N_2O and NO_2 is less and almost is not affected by the in-cylinder temperature.The proportion of NO in the emission of NO_x increases with the increase of in-cylinder temperature.From the analysis of reaction rates and chemical reaction sensitivity,it is seen that the major chemical reaction driving by which the emission of NO occurs under DME combustion in HCCI engine is extra Zeldovich mechanism and N_2O.