摘要
本文通过缸内直喷汽油机微粒测量试验,研究了怠速工况、额定转矩工况及常用工况下三效催化器对发动机尾气中微粒数量浓度及质量浓度的处理效率。研究结果表明,在怠速等低转速小负荷工况,三效催化器对粒径较小的核模态微粒的数量浓度和质量浓度均具有较高的处理效率。而随着转速及负荷的增加,其处理效率明显降低。主要原因是一方面随转速负荷提高,发动机原始排放中聚集态微粒增加,这种大粒径微粒不易被三效催化器氧化;另一方面空速增加导致微粒布朗扩散捕集作用减弱,使得三效催化器对微粒处理效率降低。
The trap efficiency of three way catalyst during different working conditions was got through GDI engine bench experiment.The results showed that,the TWC always had high processing efficiency on the particle number concentration and mass concentration(especially nuclei mode particles) when the engine was running at low speed and small load.But the processing efficiency decreased obviously with the increase of speed and load.The main reason is that engine exhaust aggregation particles increase with the speed and load increasing.The large size particle is not easy to be oxidation in three way catalyst relatively.On the other hand,the Brownian diffusion trapping effect weakened with airspeed increasing.And it leaded to lower trap efficiency.
引文
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