Using a new inversion matrix for a fast-sizing spectrometer and a photo-acoustic instrument to determine suspended particulate mass over a transient cycle for light-duty vehicles
Creators: name: Xue, Jian
name: Li, Yang
name: Quiros, David
name: Xiaoliang Wang
name: Durbin, Thomas D.
name: Johnson, Kent C.
name: Karavalakis, Georgios
name: Shaohua Hu
name: Huai, Tao
name: Ayala, Alberto
name: Heejung S. Jung
Publisher: name: Taylor & Francis
Year: 2016
Subjects: subject: Biophysics
subject: Biochemistry
subject: Cell Biology
subject: Physiology
subject: FOS: Biological sciences
subject: FOS: Biological sciences
subject: Biotechnology
subject: 39999 Chemical Sciences not elsewhere classified
subject: FOS: Chemical sciences
subject: FOS: Chemical sciences
subject: Ecology
subject: 20199 Astronomical and Space Sciences not elsewhere classified
subject: FOS: Physical sciences
subject: FOS: Physical sciences
subject: 19999 Mathematical Sciences not elsewhere classified
subject: FOS: Mathematics
subject: FOS: Mathematics
subject: Developmental Biology
subject: Cancer
subject: Inorganic Chemistry

description: Integrated particle size distribution (IPSD) is a promising alternative method for estimating particulate matter (PM) emissions at low levels. However, a recent light-duty vehicle (LDV) emissions study showed that particle mass estimated using IPSD (<i>M</i><sub>IPSD</sub>) with the TSI Engine Exhaust Particle Sizer (EEPS) Default Matrix was 56–75% lower than mass derived using the reference gravimetric method (<i>M</i><sub>Grav</sub>) over the Federal Test Procedure (FTP). In this study, <i>M</i><sub>IPSD</sub> calculated with a new inversion matrix, the Soot Matrix, is compared with <i>M</i><sub>Grav</sub> and also photoacoustic soot mass (<i>M</i><sub>Soot</sub>), to evaluate potential improvement of the IPSD method for estimating PM mass emissions from LDVs. In addition, an aerodynamic particle sizer (APS) was used to estimate mass emission rates attributed to larger particles (0.54–2.5 µm in aerodynamic diameter) that are not measured by the EEPS. Based on testing of 10 light-duty vehicles over the FTP cycle, the Soot Matrix significantly improved agreement between <i>M</i><sub>IPSD</sub> and <i>M</i><sub>Grav</sub> by increasing slopes of <i>M</i><sub>IPSD</sub>/<i>M</i><sub>Grav</sub> from 0.45–0.57 to 0.76–1.01 for gasoline direct injected (GDI) vehicles; however, for port-fuel injection (PFI) gasoline vehicles, a significant discrepancy still existed between <i>M</i><sub>IPSD</sub> and <i>M</i><sub>Grav</sub>, with <i>M</i><sub>IPSD</sub> accounting for 34 ± 37% of <i>M</i><sub>Grav</sub>. For all vehicles, strong correlations between <i>M</i><sub>IPSD</sub> and <i>M</i><sub>Soot</sub> were obtained, indicating the IPSD method is capable of capturing mass of soot particles. The discrepancy between the <i>M</i><sub>IPSD</sub> and <i>M</i><sub>Grav</sub> for PFI vehicles, which have relatively low PM emissions (0.22 to 1.83 mg/mile), could be partially due to limited size range of the EEPS by not capturing larger particles (0.54–2.5 µm) that accounts for ∼0.08 mg/mile of PM emission, uncertainties of particle effective density, and/or gas-phase adsorption onto filters that is not detected by <i>in situ</i> aerosol instrumentation. Copyright © 2016 American Association for Aerosol Research