AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
Abstract View
Theoretical and Experimental Analysis of the Core Sampling Method: Reducing Diffusional Losses in Aerosol Sampling Line
Yueyun Fu, Mo Xue, Runlong Cai, Juha Kangasluoma, JINGKUN JIANG, Tsinghua University
Abstract Number: 168 Working Group: Instrumentation and Methods
Abstract Core sampling method (extracting a portion of a flow from the core of the flow) will reduce diffusional losses of highly diffusive species (e.g., aerosol nanoparticles, ions, and gases) when transporting them through a sampling tube. Revealing parameters governing the sampling efficiency of a core sampling system, ηsam, helps to design the apparatus and to optimize its performance. In this study, we report an analytical solution for quantifying the ηsam by solving the convection diffusion equation of laminar flow field. The analytical results were experimentally evaluated using 1-5 nm tungsten oxide nanoparticles. ηsam is governed by a dimensionless loss parameter and the transport-to-sample flow ratio. Theoretically predicted values for ηsam agree with experimental results, e.g., the relative deviation is within 5% when the value for the loss parameter is less than 0.1. The core sampling method is recommended to work at the loss parameter less than 0.1 such that ηsam is equal or close to the maximum value of unity and is also insensitive to variations in sampling conditions. How to apply the findings in designing and optimizing a core sampling system was discussed. A core sampling apparatus was then designed and experimentally evaluated. Its sampling efficiency was shown to be significantly higher than those of a tee, a cross fitting, and a Y fitting when the same sampling conditions were used.
Fu et al., 2019, Aerosol Science and Technology, in press (online available: https://doi.org/10.1080/02786826.2019.1608354)