金属泡沫型微粒捕集器中颗粒物沉积特性试验研究

Experimental Study on the Deposition Characteristics of Particulate Matter in Metal Foam Particulate Filter

为了探究金属泡沫中颗粒物的沉积过程及沉积特性,自行设计开发了颗粒物快速加载系统,结合体式显微镜图像表征方法,在颗粒物加载量为1.5g/h条件下研究了平均孔径为350μm的径向型金属泡沫微粒捕集器中颗粒物沉积特性随时间及沉积深度的变化关系。结果表明:燃烧器生成的颗粒物与实际发动机的颗粒物粒径相近,金属泡沫捕集器沉积过程中始终存在深床沉积;颗粒物质量沉积速率先增加后稳定,压降增加先快后慢,碳烟质量浓度捕集效率可达82%;大部分颗粒物沉积在第1层滤芯中,末端第1层滤芯上堵塞最严重,颗粒物覆盖面积逐层减小,沉积均匀度沿径向递减;圆筒上颗粒物覆盖面积占比沿进气方向逐渐增大,第1层最末端近100%,由内至外逐层减小,孔隙则逐层增大。研究结果揭示了金属泡沫型微粒捕集器中颗粒物动态沉积过程及沉积特性变化规律,可为金属泡沫型微粒捕集器后续研究提供理论基础。

To investigate the deposition process and deposition characteristics of the particulates in metal foam,a rapid loading system for particulates was designed.Combined with the stereo microscope image characterization method,the relationships of particle deposition characteristics in the radial metal foam(the average diameter of pores is 350μm)particulate filter with time and depth were studied.The results show that the diameters of the particles from the burner are similar to that from the actual engine,and there is always a deep-bed filtration during the particle deposition in the metal foam.The deposition rate of the particles increases first with time and then becomes stable.The pressure drop increases rapidly first and then slows down.The filtration efficiency of the soot is up to 82%.Most of the particles are deposited in the first layer of the filter,which has the most severe blockage,the coverage area is reduced layer by layer,and the uniformity of deposition decreases along the radial direction.The proportion of the area covered by the particles on the sleeve gradually increases along the direction of the exhaust gas flow.At the end of the first layer,the proportion of the area covered by the particles is up to 100%.The coverage of the particles is reduced from the inside to the outside,and the pores become larger layer by layer.The results reveal the dynamic deposition process of the particulates and the change rule of deposition characteristics in the metal foam particulate filter,which provides a theoretical basis for the subsequent research of the metal foam particulate filters.