Composition and Sources of the Organic Particle Emissions from Aircraft Engines

Figures & data

TABLE 1 Conditions, engine characteristics, and fuel composition data for APEX-3 and AAFEX aircraft emissions tests

		Rated		Sulfur content	Aromatic
Test number	Engine type	thrust (kN)	Fuel type	(ppmw)	content (vol%)
APEX-3 Engines/Fuels
1	CJ6108A	13	JetA	<100	14.2
3	PW4158	258	JetA	600	16.2
4	RB211–535E4-B	192	JetA	300	21.8
5	RB211–535E4-B	192	JetA	300	20.3
6	CFM56–3B1	89	JetA	700	18
AAFEX Engines/Fuels
7	CFM56–2C1	98	JP-8	1200	18.6
8	CFM56–2C1	98	JP-8	1200	18.6
9	CFM56–2C1	98	FT-1	<10	0
10	CFM56–2C1	98	FT-2	<10	0.6
11	CFM56–2C1	98	JP-8/FT-2 blend	600	9.1

FIG. 1 Mass spectra for the factors identified using PMF for the combined APEX-3 and AAFEX organic PM emissions dataset. (Color figure available online.)

TABLE 2 High-resolution mass spectrometer molecular ion assignments

m/z	Primary ion	Secondary ion	Notes
Lube oil factor fragments
85	C5H9O, 70%	C6H11, >25%	Fragments from lubrication oil synthetic ester
113	C7H13O, 80%	C8H15, 20%
Aromatic factor fragments
77	C6H5, 90%	C4H13O, 10%	Benzene ion
91	C7H7, >95%		Toluene ion
115	C9H7, >97%		Indene ion
128	C10H8, >95%		Naphthalene ion
141	C11H9, >98%		Methylnaphthalene
Mixed hydrocarbon and oxygenated hydrocarbon fragments (contain contributions from lube oil factors, aromatic factors, and aliphatic factors)
41	C3H5, >97%		Exclusively hydrocarbon
43	C2H3O, 60%	C3H7, 40%	Oxygenate likely originates from lubrication oil
55	C3H5O, 65%	C4H9, 35%	Mixed hydrocarbon and oxygenate
57	C4H11, 90%	C3H7O, 10%	Hydrocarbon with likely lubrication oil contribution (fragmentation of C5H9O to yield C4H11 + CO)
67	C5H7, 90%	C4H5O, 10%
69	C5H9, 60%	C4H7O, >30%	Minor (<10%) contribution from other fragments
71	C5H11, >50%	C4H9O, 40%	Minor (<10%) contribution from other fragments
81	C6H9, 70%	C5H7O, 30%
83	C5H9O, >50%	C6H11, 40%	Minor (<10%) contribution from other fragments

FIG. 2 Composition of the different categories of fragments identified in Table 1 by fitting the high-resolution mass spectrometer data, as shown in Figure 2. Here, “mixed fragments” refer to fragments with contributions from the lubrication oil, aliphatic, and aromatic factors. (Color figure available online.)

FIG. 3 Organic PM mass loadings for the two representative aircraft engines: (a) RB211–535E4-B and (b) CJ6108A. Data are shown as “stacked plots” so that the total of the individual factors can be compared directly with the total organic PM loading measured by the AMS. (Color figure available online.)

FIG. 4 Lubrication oil EIs for the different engines, averaged over all available power conditions. (Color figure available online.)

FIG. 5 Composite organic PM mass loadings for all of the engines considered in this study. Data are shown as “stacked plots” so that the total of the individual factors can be compared directly with the total organic PM loading measured by the AMS. (Color figure available online.)

FIG. 6 Combustion-sourced organic PM EIs plotted as functions of power, alongside two other tracers of combustion inefficiency: benzene and black carbon soot. Data are shown for two aircraft engines: (a) RB211–535E4-B and (b) CJ6108A. ▪ Black carbon soot; • benzene (gas phase); ▴ aromatic; ▸◂ aliphatic #1; • aliphatic #2. (Color figure available online.)

FIG. 7 Parity plots between PMF-identified factors in the aircraft organic PM: aromatic factor correlates benzene emissions (a); and aliphatic #1 factor correlates with soot emissions (b). (Color figure available online.)

TABLE 3 Summary of identified components present in the organic PM emissions of aircraft engines

Component	Factor(s)	Key masses	Quantification evidence	Composition evidence
Lubrication oil	Lube #1	85,113,127,141	(1) Not a strong function of engine power or combustion efficiency (2) Varies with manufacturer and engine model	Matches key mass spectrum features observed for Air BP, dominant (90%) for engines using Air BP lubrication oil Yu et al. (2010, 2012)
	Lube #2	55,57,85		Significant contribution (50%) for engines using Mobil II lubrication oil
Combustion	Aromatic	77,91,105, 115,128,141	Scales with engine power and combustion efficiency	(1) High-resolution mass spectrometer data show that key masses are >90% hydrocarbon (2) Scales with gas phase benzene emissions at low power
	Aliphatic #1	41/43, 55/57, 67/69/71, 79/81/83/85		Scales with PM soot emissions at high power
Atmospheric/ Combustion	Aliphatic #2	27, 41/43, 55	(1) Contains mass features common in atmospheric PM (2) Quantity increases with increasing dilution	Hig- resolution spectrometer data shows substantial oxygen content
Contaminant	Siloxane	73,147,207	Present only when silicone tubing used in sampling system	Matches key mass spectrum features observed in silicon oils Timko et al. (2009)

Yu , Z. H. , Herndon , S. C. , Ziemba , L. D. , Timko , M. T. , Liscinsky , D. S. Anderson , B. E. 2012 . Identification of Lubrication Oil in the Particulate Matter Emissions from Engine Exhaust of In-Service Commercial Aircraft . Environ. Sci. Technol. , 46 : 9630 – 9637 .

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Timko , M. T. , Yu , Z. H. , Kroll , J. , Jayne , J. T. , Worsnop , D. R. Miake-Lye , R. C. 2009 . Sampling Artifacts from Conductive Silicone Tubing . Aerosol Sci. Technol. , 43 : 855 – 865 .

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