AAAR 33rd Annual Conference
October 20 - October 24, 2014
Rosen Shingle Creek
Orlando, Florida, USA
Abstract View
A Portable Water Condensation Particle Counter
SUSANNE HERING, Steven Spielman, Gregory Lewis, Aerosol Dynamics Inc.
Abstract Number: 70 Working Group: Instrumentation and Methods
Abstract A small, water-based condensation particle counter has been developed for portable monitoring of particle number concentrations. This instrument uses a three-stage, temperature-moderated laminar flow condensation method, with a self-sustaining wick. It has no fluid reservoirs, and may be operated in any orientation. Once wetted, it sustains operation for days to weeks. This self-sustained operation is enabled through a combination of recovery of evaporated water within the growth region, and capture of water vapor from the sampled air. The length of operation without addition of water depends on the absolute relative humidity of the sampled air stream, the thickness of the wick material, and operating temperatures. The aerosol flow rate is 0.2-0.3 L/min. The most recent design of the condensational growth section, which is the instrument without its optics head and control board, measures 7cm x 4cm x 11cm, weighs 320g. In tests with the first, somewhat larger, prototype, the detection efficiency for 6nm sodium chloride aerosols is 80%. For particles larger than 10nm the detection efficiency is above 90%. In comparison to the TSI-3788 ultrafine WCPC while sampling ambient air over a two day period, the the correlation between the portable WCPC gives R2>0.99, with regression slope of 0.95. For comparison over two weeks of unattended operation the correlation decreases to R2=0.97, with regression slopes of 0.89. Efforts are underway to incorporate this technology into portable device suitable for hand-held or personal monitoring.