REACTION MODELING OF AUTO-IGNITION AND EXHAUST EMISSION IN COMPRESSION-IGNITION COMBUSTION

建立了三种不同类型的柴油机压燃过程与排放分析相结合的反应模型：第一种模型用Edelman一步全域机制描述了燃料高温氧化为CO和H_2的过程，然后详细地研究了CO和H_2的氧化动力学。这些反应被集成在随机模型中，该模型描述了不同温度和不同组分浓度的气泡在湍流混合中的随机碰撞。计算结果与柴油机排气中NO浓度的实测值吻合较好。第二个模型不仅描述了燃烧过程中的放热过程，还反映了碳烟生成过程中的裂解过程。该模型由C_2碳氢化合物化学C_mH_n*Ac_2H_4+BC_4H_9：N-C_4H_9*C_2H_4+C_2H_5；I-C_4H_9*C_3H_6+CH_3组成。CH4、C2H4、C2H6和C3H6组分的计算值与实测值吻合较好。第三个模型描述了预混压燃过程的低温氧化机理。在Keck模型的基础上，通过修正速率常数、活化能和终止反应机理来建立模型，以符合现有的实验结果，该模型将为未来潜在的内燃机之一开发的预混式压燃式发动机的自燃过程提供一个更符合实际的模型。

Three different types of reaction models have been developed for the compression-ignition process in Diesel engines to be coupled with exhaust emission analyzes.The first model is to describe the high temperature oxidation process from fuel to CO and H_2 with one-step global mechanism of Edelman followed by a detailed kinetics of the oxidation of CO and H_2. In addition to these models, a model for NO formation including prompt NO and thermal NO were taken into account. These reactions were integrated in the stochastic model which expressed the random collisions in turbulent mixing between gas blobs having different temperatures and species concentrations. The computed results compared well with measurements of NO concentration in Diesel exhaust.The second model expresses not only the heat release but also the cracking process which is essential to modeling the soot formation. The model consists of following multi-step global reactions based on the Rice-Herzfeld mechanism and the C_2 hydrocarbon chemistry.C_mH_n*aC_2H_4+bC_4H_9 : n-C_4H_9*C_2H_4+C_2H_5 ; i-C_4H_9*C_3H_6+CH_3The rate constant for the above global reaction was obtaned by comparing with the ignition delay measured in a rapid compression machine. The computed fractions of CH_4, C_2H_4, C_2H_6 and C_3H_6 showed good agreement with measurements.The third model describes the low temperature oxidation mechanism which is needed to analyze a premixed compression-ignition proces. Based on Keck's model, the model has been established by modifying rate constants, activation energies and the mechanism of the termination reaction to fit existing experimental results.The models developed in this study will lead to a more realistic model to combine the high and low temperature mechanisms for the auto-ignition process in the premixed compression-ignition engines being developed for one of the potential future internal combustion engines.