10th International Aerosol Conference September 2 - September 7, 2018 America's Center Convention Complex St. Louis, Missouri, USA
Abstract View
Laboratory Testing of Gas Exchange Efficiency in a Cylindrical Counter Flow Denuder
HAGINO HIROYUKI, Japan Automobile Research Institute (JARI)
Abstract Number: 17 Working Group: Instrumentation
Abstract Many applications for aerosol particle measurement and calibration particle generation require removal of gaseous components. Diffusional separation techniques are widely used for this purpose. However, the use of these denuder techniques is limited when less reactive and/or inert gases (i.e., O2, CO2, and H2O) need to be exchanged continuously. In this study, a cylindrical counter flow denuder was developed using a microporous glass tube to obtain a denuder system that had exchange of gases. The denuder performance for gas exchange was evaluated using experimental parameters in a laboratory test.
The denuder was designed to exchange gases in the sample flow by diffusion to the purge flow across a cylindrical microporous glass tube. The cylindrical counter flow denuder had two concentric tubes; an inner porous tube through which aerosol particles were passed as sample flow; and an outer tube made of seamless stainless steel with counter-current purge gas supply as purge flow, in opposite direction to the sample flow. The inner tube for sample gas flow was designed with maximum dimensions and had a center channel (250 mm length, 5 mm o.d., and a pore size of 0.1 μm) through which the aerosol and gas were passed. Several evaluation tests for gas exchange were performed with sample flow tubes made of different types of outer tube and the length counter-current flow diffusion denuder. The sample flow rate of the counter flow denuder was set at 0.15 L/min, as it was used as an inlet of the Aerosol mass spectrometer (AMS).
Laboratory test results indicated that removal efficiencies of gases increased with higher sample to purge flow rate ratio. However, the dimension of outer that was related with purge gas residence time did not affect significantly gas removal efficiency following optimization of sample and purge flow rate conditions. Significantly high gas exchange efficiency was obtained for the length of the denuder that is corresponding to the residence time in sample flow channel.