AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Effect of Particle Properties on Relative Response of Real Time Black Carbon Mass Concentration Instruments
Ali Momenimovahed, KEVIN THOMSON, Mark Johnson, Jason S. Olfert, Matthew Dickau, Andrew Crayford, Yura Sevcenco, Paul Williams, Benjamin Brem, Gregory Smallwood, National Research Council Canada
Abstract Number: 350 Working Group: Instrumentation and Methods
Abstract Nanoparticle aerosols in the atmosphere can have a significant effect on climate by scattering and absorbing solar radiation. Highly absorbing particles, like those composed of black carbon (BC), can absorb and re-emit solar radiation causing a net heating effect (Forster et al., 2007). There are a number of commercially available mass measurement instruments that are used to measure the BC concentration from different sources such as engines and burners in real-time. However, the effect of the physical and chemical properties of the particles on mass concentrations measured by different instruments is not fully understood yet. This study focusses on particles produced by two nominally identical gas turbines to investigate the influence of particle properties on relative response of several mass measurement techniques including photo acoustic spectroscopy (PAS), laser induced incandescence (LII), and cavity extinction with total scattering (Ex-Sc). The mass concentrations are measured at both low and high power operating conditions where different particle characteristics are observed. Cavity extinction with total scattering at three different wavelengths (450, 530 and 780 nm) was employed to study the variation of the particle optical properties with power condition and measurement wavelength. To evaluate the effect of particle size, a centrifugal particle mass analyzer (CPMA) upstream of the measurement instruments was employed as an impactor by changing its rotational speed to progressively remove large particles, lowering the median diameter of the measured particles. Finally, the ratio of elemental to organic carbon was quantified by thermal optical analysis, and by comparing mass and number concentration of non-volatile versus volatile material using a catalytic stripper with a DMA and a CPMA.
Forster, P., et al. (2007). Climate Change 2007: The Physical Science Basis, Chapter 2. Cambridge University Press.