AAAR 37th Annual Conference October 14 - October 18, 2019 Oregon Convention Center Portland, Oregon, USA
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Design and Development of a Cylindrical Calibration Chamber for Laboratory Evaluation of Low-cost Particulate Matter Sensors
TOFIGH SAYAHI, Dylan Kaufman, Tom Becnel, Kamaljeet Kaur, Anthony Butterfield, Scott Collingwood, Yue Zhang, Pierre-Emanuel Gaillardon, Kerry Kelly, University of Utah
Abstract Number: 334 Working Group: Air Quality Sensors: Low-cost != Low Complexity
Abstract The performance of low-cost PM sensors is commonly characterized using laboratory calibration. This type of calibration typically exposes the sensors and a reference monitor to PM inside a cubic chamber. Few studies have provided an evaluation of the ability of their calibration chamber/procedure to provide a uniform particle distribution. In this study, we designed and evaluated a cost-effective cylindrical calibration chamber capable of continuously providing a uniform PM concentration simultaneously to 8 low-cost PM sensors. The chamber development and evaluation were based on a Computational Fluid Dynamics (CFD) model and a rigorous experimental protocol. Using both of these strategies, we systematically evaluated the ability of the chamber to generate stable PM concentrations and to produce repeatable calibration curves, regardless of sensor position within the chamber. We also used this new chamber to assess 242 Plantower PMS 3003 sensors from two purchased batches. The CFD model and experimental results showed that the chamber is capable of providing a uniform PM concentration to calibrate eight sensors at one time within 6% concentration difference and with excellent reliability (intraclass correlation coefficient > 0.771). We also performed a CFD simulation of a cubic chamber with the same volume and under the same conditions and found a greater concentration difference (16.4%). The results identified two malfunctioning sensors and demonstrated that all the sensors (except for the malfunctioning sensors) were highly correlated with the DustTrak reference monitor (R2>0.978). The study also identified significant response differences between batch I and II. As in several other studies, the PMS sensors exhibited a statistically significant difference in their responses to two different aerosol types. Overall, this chamber can be used to complement field observations and help to eventually determine whether good laboratory performance of a low-cost PM sensor indicates its good performance under real-world conditions.