10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Application of Centrifugal Filter to Measurement of Aerosol Size Distribution
RYO OZAWA, Yoshio Otani, Takafumi Seto, Kanazawa University
Abstract Number: 307 Working Group: Instrumentation
Abstract In recent years, with the growing interest in indoor air quality and the atmospheric environment, removal and analysis of aerosol is becoming increasingly important. Although there are various filters suitable for the particle size range and type of aerosol, few filters can maintain a high aerosol collection efficiency while keeping a low airflow resistance. We have proposed a new type of air filter called as “centrifugal filter” in which a cylindrical filter rotates along the axis parallel to the air flow (Nakajima et al. 2015). The collection efficiency of centrifugal filter is adjustable by changing the rotation speed without changing the pressure drop. Since the collection efficiency of centrifugal filter is varied by changing the rotation speed of filter to attain various cut-off sizes, it may be combined with a particle detector which does not have size-discrimination capability to form a new type of measurement system. By scanning the rotation speed of centrifugal filter followed by the detection of total aerosol concentration, and applying an appropriate inversion scheme from the particle penetration to the size distribution, we may construct a real time aerosol measurement system based on the aerodynamic size as SMPS measures the size distribution based on mobility diameter by scanning the voltage. However, because the classification performance of the centrifugal filter is not so high, inversion method using 50% cutoff diameter cannot be used. In this work, we developed the new inversion method that gives frequencies of an arbitrary size distribution function by using a least square method. We applied the inversion method to the measurement of size distribution of Kanto Loam test dust (JIS-11). JIS-11 particles were dispersed by a fluidized-bed aerosol generator (Model 3211, Kanomax Inc.) and electrically neutralized and mixed with a clean air to make the volumetric flow rate equal to 7 L/min. The inlet and outlet concentrations of JIS-11 were measured with a photometer (Dust track, Model 8530, TSI) by changing the rotation speed of centrifugal filter. We compared the size distributions of particles converted by the present inversion method and those measured by an optical particle counter (OPS, Model 3330, TSI). As a result, we found a good agreement between those measured by the centrifugal filter and the OPS.