AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Centrifugal Separator for Micron Size Aerosol Particles
SHU NAKAO, Hiromu Matsubara, Mikio Kumita, Hidenori Higashi, Osamu Akasaka, Yoshiki Hayasaki, Takafumi Seto, Yoshio Otani, Kanazawa University
Abstract Number: 680 Working Group: Remote and Regional Atmospheric Aerosols
Abstract Simple and low-pressure loss centrifugal separator of micron-sized aerosol particle was developed. The separator is composed of a cylinder, two rotary joints and a motor. When the cylinder is rotated at the rotation speed of 500 to 3,000 rpm, swirl flow is generated in the cylinder. The aerosol particles introduced to the separator was transported by the centrifugal force with traveling by the swirl flow. As a result, the particles larger than the critical diameter are trapped on the wall of the cylinder depending on the particle size, gas velocity and rotation speed.
In order to evaluate classification performance, the polystyrene latex (PSL) particles of 0.5-5.0 micron-meter in diameter were used as test particles. The test particles generated by nebulizer were introduced in the cylinders at a flow rate of 1 and 5 L/min. The collection efficiency was determined by measuring the particle number concentrations before and after the cylinders by an optical particle counter (OPC). Pressure drop was also measured by differential pressure gauge.
The collection efficiencies for 0.5-2.5 micron-meter particles by the separator without rotation were as low as 25 (1 L/min) to 20% (5 L/min). Significant increase in the collection efficiencies of micron-particles was observed when the cylinder is rotated and the collection efficiency increased with rotation speed. At the maximum rotation speed of 3,000 rpm, more than 95 % of the 2.5 micron-meter particles were collected by the separator at 1 L/min. Therefore the centrifugal separator is considered to be effective to control the cut-off diameter by changing the rotation speed. On the other hand, the pressure drops of the separator were as low as 3 Pa (1 L/min) to 15 Pa (5L/min) and they did not change significantly with the rotation. Therefore the aerosol centrifugal separator is expected to be a size-tunable and low pressure loss classifier which can be used as a pre-filter of various kinds of aerosol instruments.