Development of Particulate Matter Measurement by UV Absorbance on Marine Diesel Engine

透光率是测量柴油机尾气中小颗粒物浓度的有效方法之一。由于紫外光源的消光系数比可见光高，因此改进了测量方法。证明了聚苯乙烯标准粒子在直径为10 ~ 300nm和一定波长范围内的消光系数和PM的折射率。这一想法使得从柴油发动机中排放的高达0.03克/立方米（0.1克/千瓦时）的颗粒具有较小的光路长度、高灵敏度和低浓度范围。该测量装置由波长为365nm的高压汞灯、透镜、干涉滤光片和小型光传感器组成。输出信号由个人计算机系统实时分析。测定了标准颗粒和PM的吸收光谱。用朗伯-比尔定律测定吸光度。该系统的应用使直接测量的PM浓度与过滤采样法的数据符合得很好。这一发展将导致船舶发动机PM浓度的实用价值的建立。

Light transmittance is one of the effective measurement method of small particlulate matter (PM) concentration in diesel exhausted gas. The measurement is improved by UV light source, because the extinction coefficient in the UV is higher than in visible light. It was proved that the extinction coefficient of a standard particle of polystyrene and PM estimated refractive indices were calculated with the diameter from 10 to 300nm and some wavelength. That idea makes a small light path length, high sensitivity and low concentration range for particles up to 0.03g/m3 (0.1g/kWh) exhausted from a diesel engine. The measurement is composed of a high pressure Hg lamp with the wavelength of 365nm, lenses, an interference filter and a small light sensor. The output signal is analyzed at real time by a personal computer system. The absorption spectra of the standard particles and PM were examined. The concentration was determined by the absorbance with Lambert-Beer's law. Application of the system has enabled directly measurement of PM concentration which were in fair agreement with the data by filter sampling method. This development will lead to a building up of the practical value of PM concentration from marine engines.