Abstract View
Performance of Black Carbon Instruments for Extractive Remote Emission Sensing
MARKUS KNOLL, Benjamin Lang, Alexander Bergmann, Graz University of Technology
Abstract Number: 171
Working Group: Instrumentation and Methods
Abstract
Black carbon (BC) is well known for having an impact on health and our environment, whereby combustion-based vehicles are one of the main contributors. Studies have shown that comparatively few vehicles are responsible for a large fraction of the overall particulate emissions. However, current enforcement strategies are ineffective in identifying these high emitting in-use vehicles. Remote emission sensing (RES) is a promising approach for identifying these high emitters. Commercial RES systems are delivering accurate emission factors for gaseous species but lack accuracy for particulates. Extractive point sampling (PS) is one potential approach for measuring particulates remotely. Due to the transient nature of emission events caused by passing vehicles and exhaust dilution by ambient air, instruments must be able to capture those events and resolve small concentrations. In studies examining such extractive approaches, laboratory-grade instruments like the Aethalometer AE33 (Magee Scientific) have been used.
In this work, a custom-designed photoacoustic BC sensor (PA-BCS) optimized for RES is compared to two state-of-the-art BC instruments for their applicability in PS. These are an AE33 and a Microsoot Sensor Plus (MSSPlus, AVL List GmbH). The instruments are compared concerning their limit of detection (LOD), sensitivity, and response time, which are essential factors for RES.
A comparable LOD (~1 µg/m³ at 1 s averaging time) could be reached for all instruments. Measurements with varying BC concentrations showed high correlations (R² > 0.98) between the instruments. Response time measurements revealed that the PA-BCS and MSSPlus feature significant shorter rise and fall times than the AE33. Comparing the deviations between the responses, considerable differences could be observed between the two photoacoustic instruments (PA-BCS, MSSPlus) and the AE33. These investigations bring along more insights into the applicability of these instruments in point sampling RES.