Investigation of the influence of humidity on the ultrasonic agglomeration of submicron particles in diesel exhausts
Investigation of the influence of humidity on the ultrasonic agglomeration of submicron particles in diesel exhausts
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DOI：
10.1016/s0041-624x(02)00452-3
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发表时间：
2003-06-01
期刊：
影响因子：
4.2
通讯作者：
Dorronsoro-Areal, JL
中科院分区：
文献类型：
--
作者：
de Sarabia, ERF;Elvira-Segura, L;Dorronsoro-Areal, JL
去除柴油燃烧中产生的0.01-1微米范围内的非常细的颗粒物对于减少空气污染很重要，因为这些颗粒物对环境有影响。通过形成较大的颗粒，亚微米颗粒的声学团聚被认为是一种很有前途的工艺，可以提高现有过滤系统的颗粒去除效率。然而，一些作者指出，对于较大的颗粒，声波团聚比对较小的颗粒更有效。在21 kHz频率下，研究了湿度对纳米尺度柴油机排气微粒声学团聚的影响。凝聚试验的实验装置主要由柴油机中试装置、超声凝聚室、稀释系统、喷嘴雾化器和气溶胶采样测量站组成。超声处理由四个高功率阶梯板换能器组成的线性阵列产生，对流速为900N m(3)/h的烟雾的处理效果是略微减少了燃烧室出口的颗粒物数量浓度。然而，湿度的存在使颗粒数浓度降低了56%，从而提高了团聚速率。由相互辐射压力产生的正动力学和流体动力凝聚系数的线性组合的凝聚过程的数值研究也发现，声学凝聚随着湿度的增加而增强。这两个结果都证实了使用高功率超声波和湿度来增强远小于IGM的颗粒的团聚的好处。(C)2002 Elsevier Science B.V.保留所有权利。
Removing very fine particles in the 0.01-1 mum range generated in diesel combustion is important for air pollution abatement because of the impact such particles have on the environment. By forming larger particles, acoustic agglomeration of submicron particles is presented as a promising process for enhancing the efficiency of the current filtration systems for particle removal. Nevertheless, some authors have pointed out that acoustic agglomeration is much more efficient for larger particles than for smaller particles. This paper studies the effect of humidity on the acoustic agglomeration of diesel exhausts particles in the nanometer size range at 21 kHz. For the agglomeration tests, the experimental facility basically consists of a pilot scale plant with a diesel engine, an ultrasonic agglomeration chamber a dilution system, a nozzle atomizer, and an aerosol sampling and measuring station. The effect of the ultrasonic treatment, generated by a linear array of four high-power stepped-plate transducers on fumes at flow rates of 900 N m(3)/h, was a small reduction in the number concentration of particles at the outlet of the chamber. However, the presence of humidity raised the agglomeration rate by decreasing the number particle concentration by up to 56%. A numerical study of the agglomeration process as a linear combination of the orthokinetic and hydrodynamic agglomeration coefficients resulting from mutual radiation pressure also found that acoustic agglomeration was enhanced by humidity. Both results confirm the benefit of using high-power ultrasound together with humidity to enhance the agglomeration of particles much smaller than I gm. (C) 2002 Elsevier Science B.V. All rights reserved.