汽车尾气三效催化器排气系统冷启动阶段数值模拟

Mathematical simulation of automotive exhaust catalytic converter in exhaust system of cold-start engine

发动机冷启动状态汽车尾气的排放情况对尾气排放控制起着关键的作用,建立了发动机冷启动状态排气系统传热、传质的非稳态单通道数学模型,通过对模型的数值求解,分析了汽车尾气排气系统温度、浓度的演变,经与实验结果对比,模型拟和与实验值能很好吻合,所建模型和选择参数正确.模拟了催化器内尾气温度场、浓度场的分布情况,对催化器的研究、设计具有重要意义.

The engine emission in the cold-start phase plays an important role in reducing the overall emission in the tailpipe. Simulating cold-start engine behavior is a difficult task as it involves heat transfer processes and chemical reactions at both the exhaust pipe and catalytic converter. This paper presents a mono-channel non-steady model for the heat and mass transfer in the exhaust system of cold-start phase engine, both spatially and temporally. With the aid of numerical calculations, thermal and mass transfer characteristics of the exhaust system were analyzed. The calculation results were in agreement with experiments. The conversions of carbon monoxide, unburned hydrocarbons and nitrogen oxides were supported by the experimental data. The temperature and concentration distributions in the three-way monolithic converter were also discussed, which are necessary for the research and design of converter.