Measurement of Aircraft Engine Non-Volatile PM Emissions: Results of the Aviation-Particle Regulatory Instrumentation Demonstration Experiment (A-PRIDE) 4 Campaign

Abstract

This study reports the first of a kind data on aircraft engine non-volatile particulate matter (nvPM) number-and massbased emissions using standardized systems. Two compliant sampling and measurement systems operated by Missouri University of Science and Technology (Missouri S&T) and Empa were evaluated during the Aviation-Particle Regulatory Instrumentation Demonstration Experiment (A-PRIDE) 4 campaign at the SR Technics facilities in Z€ urich, Switzerland, in November 2012. The Missouri S&T and Empa systems were compared during a series of dedicated engine tests using a CFM56-5B4/2P engine source, and maintenance engine testing using CFM56-7B24/3 and PW4168A engine sources at a range of engine operating conditions. These two compliant systems were found to agree within 6% of each other in terms of nvPM number-based emissions, and within 15% for nvPM mass-based emissions. For the three engine sources studied, at several engine power conditions the mass instruments approached their limit of detection, resulting in high measurement uncertainties. Ancillary instrumentation was used to determine PM size distributions, chemical composition, and effective density from mass-mobility experiments. Particle geometric mean mobility diameter ranged 20-45 nm, and geometric standard deviation varied from 1.55 to 1.9 for the three engine types studied. The fraction of PM organic content measured in the emissions from the CFM56-5B4/2P engine was »4% while the size-dependent particle effective density was parameterized with a massmobility exponent of 2.57 and a pre-factor of 0.606. Results of this study will contribute to the development of the new nvPM emissions certification standard and emissions inventories from commercial aviation operations.

Effective density and volatility of particles sampled from a helicopter gas turbine engine

“…In the case of large amounts of volatile material, the mass of volatile material greatly outweighs the mass of soot, the particle becomes spherical, and the effective density approaches the material density of the volatile material. Lobo et al (2015) used a similar dilution system (with dilution ratio of ~10) and their effective density data is similar to the measurements from the Gnome engine. On the other hand, Abegglen et al (2015) and Durdina et al (2015) did not dilute their sample for the majority of their tests but used a dryer to remove water from the aerosol.…”

“…Lobo et al (2015) used a similar dilution system (with dilution ratio of ~10) and their effective density data is similar to the measurements from the Gnome engine. On the other hand, Abegglen et al (2015) and Durdina et al (2015) did not dilute their sample for the majority of their tests but used a dryer to remove water from the aerosol. (In comparison tests, Durdina et al (2015) found that at high thrust the effective densities of diluted and undiluted samples were similar).…”

“…In these experiments the catalytic strippers upstream and downstream of the DMA were not used and the measurements represent the effective density of the particles including any volatile material condensed on the surface. The power-law relationships based on the fit of the data are shown in the figure and these relationships are used to calculate the mass distributions shown in the Gnome engine to that of undenuded soot from a CFM56-5B4/2P (Lobo et al 2015) and a CFM56-7B26/3 (Abegglen et al 2015;Durdina et al 2014). The dark shaded region is the range bounded by Abegglen et al (2015) fit curves from 22% engine thrust (lower boundary) to 118% thrust (upper boundary).…”

“…Non-volatile particles from aircraft engines typically form as aggregates of carbon primary particles typically 10-20 nm in diameter (Liati et al 2014;Boies et al 2015), bound together in fractal-like branching chain structures. Sizes of such aggregates generally appear in distributions with count median mobility-equivalent diameters of 10 to 40 nm (Kinsey et al 2010;Boies et al 2015;Lobo et al 2015). Here, we will use the term ‗soot' to refer to these aggregates excluding any other species (e.g.…”

“…The mass-mobility relationship is often expressed in term of the particle effective density, defined as the mass divided by the mobility-equivalent volume, which is often measured using a differential mobility analyzer (DMA) with a centrifugal particle mass analyzer (CPMA) or an aerosol particle mass analyzer (APM), and condensation particle counter (CPC). The effective densities of soot are typically found to follow a power-law relationship, with effective density decreasing for increasing mobility-equivalent diameters Johnson et al 2015;Lobo et al 2015;Abegglen et al 2015).…”