AAAR 36th Annual Conference October 16 - October 20, 2017 Raleigh Convention Center Raleigh, North Carolina, USA
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Aerosol Loading Effects on Particle Size-Selective Samplers
SHENG-HSIU HUANG, Chih-Wei Lin, Ting-Ju Chen, Yu-Mei Kuo, Chih-Chieh Chen, National Taiwan University
Abstract Number: 456 Working Group: Instrumentation and Methods
Abstract The main objective of this work was to characterize the particle loading effects on size-selective samplers as a function of particle size. Five PM2.5 cyclones of different body diameters similar to VSCC were fabricated to investigate the effects of particle loading. An ultrasonic atomizing nozzle was used to generate micrometer-sized potassium sodium tartrate (PST) particles (CMD=3 μm, GSD=1.42, conc.=4.3 mg/m3) and Sodium chloride (NaCl) particles (CMD=3 μm, GSD=1.3, conc.=3.5 mg/m3) as solid and di-ethyl-hexyl-sebacate (DEHS) particles (CMD=3 μm, GSD=1.37, conc.=5.5 mg/m3) as liquid challenge particles. Aerosol number size distributions and concentrations, both upstream and downstream of the cyclones, were measured using an aerodynamic particle sizer. Each cyclone was tested for loading effects in the same chamber for an hour. We also evaluated the effects of other operating parameters, including challenge aerosol size distribution, chamber humidity, and the material of the cyclone.
During loading test with PST particles, aerosol penetration of particles of 2.5-μm in diameter decreased drastically at the first 20 minutes of the test, then became stabilized at the same penetration level, with an average decrease of 20%. In addition, the time for the curve to reach equilibrium differed by particle size, but not affected by the cyclone body diameter. Liquid aerosols did not cause loading effect, apparently due to the deposited liquid draining down to the grit pot. This aerosol loading effects were found to be influenced not only by the size distribution of the challenge aerosols, but also the environmental condition of the test chamber, the test agent, the cyclone material, and even the surface roughness of the cyclone and the challenge aerosol particles.