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Black Carbon Measurements of Flame-Generated Soot as Determinedby Optical, Thermal-Optical, Direct Absorption,and Laser Incandescence Methods
Citation:
Yelverton, T. L., M. D. Hays, B. K. Gullett, AND W. P. Linak. Black Carbon Measurements of Flame-Generated Soot as Determinedby Optical, Thermal-Optical, Direct Absorption,and Laser Incandescence Methods. ENVIRONMENTAL ENGINEERING SCIENCE. Mary Ann Liebert, Inc., Larchmont, NY, 31(4):209-215, (2014).
Impact/Purpose:
This investigation sought to compare commercially available measurement techniques for black carbon (BC), as a standard definition for BC does not exist outside of the operational definition each instrument manufacturer incorportaes. For the investigation, a lab-generated, constant source was utilized to compare ten measurement techniques for BC concentation, and the findings are reported within this manuscript.
Description:
Black carbon (BC), light absorbing particles emitted primarily from incomplete combustion, is operationally defined through a variety of instrumental measurements rather than with a universal definition set forth by the research or regulatory communities. To examine the consistency of these measurements, an intercomparison study examined a set of ten semi-continuous and time-integrated measurement techniques and methods widely used to determine BC concentrations in the atmosphere and in combustion emissions from sources. The instruments included in the study are a multi-angle absorption photometer (MAAP), a transmissometer, three aethalometers (rack-mount, portable, and micro), a thermal-optical carbon analyzer (using IMPROVE, NIOSH 5040, and NIST-EPA methods), a single particle soot photometer (SP2), and a three wavelength photoacoustic soot spectrometer (PASS3). A consistent source of particles was generated using a small, diluted, ethylene-air diffusion flame. The measured BC concentration values averaged approximately 30 µg/m3 with variation of less than 15% across a measurement technique, but up to 50% across methodologies. The imprecision of the measurements is compounded by an apparent inability to close a carbon mass balance, suggesting an accompanying accuracy question in which BC may be significantly underestimated.
