CH_(4)+C_(2)H_(5)OH+Ar体系热解的气相动力学研究

Gas-phase Kinetic Study of Pyrolysis in the System of CH_(4)+C_(2)H_(5)OH+Ar

通过化学气相渗透工艺,利用以CH_(4)和C_(2)H_(5)OH为前驱体制备碳/碳复合材料,可以提高沉积速率且易得到高织构的热解炭。探究其反应机制可以更好地用于计算流体力学(CFD)研究。化学反应机制往往包含大量自由基和反应,而以实验为主手动构建反应机制很容易遗漏重要物质和反应。本研究利用反应机制生成器(RMG)构建了CH_(4)+C_(2)H_(5)OH+Ar体系详细的气相热解动力学机制,其涵盖31种核心物质和214个核心反应,预测了主要物质形成和消耗的趋势,模拟结果与实验结果趋势相吻合。通过详细的动力学机制研究和反应物以及部分重要产物灵敏度分析,识别了影响关键物质生成和消耗的反应。反应路径分析揭示了详细机制中不同物质之间的关系,并确定了机制中的核心物质。在温度1373 K、压力10 kPa条件下,依据灵敏度分析和路径分析的结果对详细机制进行了简化,得到包含18种物质和44个反应的气相简化动力学机制。该简化机制在保留关键物质的同时显著提高了计算效率,为进一步CFD研究和应用提供了更为便利的基础。

Preparation of carbon-carbon composites through the chemical vapor infiltration(CVI)process,utilizing CH_(4)and C_(2)H_(5)OH as precursors,can effectively improve the deposition rate and produce highly structured pyrolytic carbon.Understanding the reaction mechanism is essential for computational fluid dynamics(CFD)studies.Chemical reaction mechanisms typically involve numerous free radicals and reactions,and manually constructing such mechanisms based on experimental data alone risks omitting critical species and reactions.Hence,in this research,a thorough gas-phase pyrolysis kinetic mechanism for the CH_(4)+C_(2)H_(5)OH+Ar system was developed using the reaction mechanism generator(RMG).This mechanism included 31 core species and 214 core reactions,accurately predicting the evolution of major species'formation and consumption.The simulation results were consistent with experimental observations.Through a detailed analysis of the kinetics and sensitivity of reactants and critical products,reactions influencing the formation and consumption of crucial species were identified.Reaction pathway analysis further clarified relationships among different species,identifying core species within the mechanism.By simplifying the detailed mechanism based on sensitivity and rection pathway analysis at 1373 K and 10 kPa,a gas-phase kinetic mechanism was derived,composed of 18 species and 44 reactions.This streamlined model substantially boosts computational efficiency while retaining key species,providing a more convenient foundation for further CFD studies and applications.