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Comparison of PM Emissions from a Commercial Jet Engine Burning Conventional, Biomass, and Fischer–Tropsch Fuels

Rising fuel costs, an increasing desire to enhance security of energy supply, and potential environmental benefits have driven research into alternative renewable fuels for commercial aviation applications. This paper reports the results of the first measurements of particulate matter (PM) emissions from a CFM56-7B commercial jet engine burning conventional and alternative biomass- and, Fischer-Tropsch (F-T)-based fuels. PM emissions reductions are observed with all fuels and blends when compared to the emissions from a reference conventional fuel, Jet A1, and are attributed to fuel properties associated with the fuels and blends studied. Although the alternative fuel candidates studied in this campaign offer the potential for large PM emissions reductions, with the exception of the 50% blend of F-T fuel, they do not meet current standards for aviation fuel and thus cannot be considered as certified replacement fuels. Over the ICAO Landing Takeoff Cycle, which is intended to simulate aircraft engine operations that affect local air quality, the overall PM number-based emissions for the 50% blend of F-T fuel were reduced by 34 ± 7%, and the mass-based emissions were reduced by 39 ± 7%.

Physical characterization of aerosol emissions from a commercial gas turbine engine

This paper discusses the results of the Aircraft Particle Emissions Experiment Project for the physical characterization of total (nonvolatile plus volatile) aerosol emissions (emission factors, hydration properties, and distribution shape parameters) by extractive sampling from an on-wing CFM56-2C 1 engine. Samples were extracted at the engine exit plane (1 m) as well as locations 10 and 30 m downstream. Three different fuels were used in this study: base fuel, high-sulfur fuel, and high-aromatic fuel. For the 1 and 10-m probe locations, strong and sometimes nonlinear dependencies were observed on fuel flow rate and no statistically significant dependencies were observed for fuel composition. At 30 m, the onset of gas-to-particle conversion was apparent for low- to medium-fuel flow rates. The soluble mass fraction was found to increase with distance from the engine exit plane and with increasing fuel aromatic and sulfur content. An intercomparison of gas and particle sampling trains showed that gas-to-particle conversion is a serious sample train artifact for gas sampling trains in which dilution cannot be achieved at the probe tip.

N-acetylcysteineamide (NACA) prevents inflammation and oxidative stress in animals exposed to diesel engine exhaust

Diesel exhaust particles (DEPs), a by-product of diesel engine exhaust (DEE), are one of the major components of air borne particulate matter (PM) in the urban environment. DEPs are composed of soot, polycyclic aromatic hydrocarbons (PAHs), redox active semi-quinones, and transition metals, which are known to produce pro-oxidative and pro-inflammatory effects, thereby leading to oxidative stress-induced damage in the lungs. The objective of this study was to determine if N-acetylcysteineamide (NACA), a novel thiol antioxidant, confers protection to animals exposed to DEPs from oxidative stress-induced damage to the lung. To study this, male C57BL/6 mice, pretreated with either NACA (250mg/kg body weight) or saline, were exposed to DEPs (15mg/m(3)) or filtered air (1.5-3h/day) for nine consecutive days. The animals were sacrificed 24h after the last exposure. NACA-treated animals exposed to DEP had significant decreases in the number of macrophages and the amount of mucus plug formation in the lungs, as compared to the DEP-only exposed animals. In addition, DEP-exposed animals, pretreated with NACA, also experienced significantly lower oxidative stress than the untreated group, as indicated by the glutathione (GSH), and malondialdehyde (MDA) levels and catalase (CAT) activity. Further, DEP-induced toxicity in the lungs was reversed in NACA-treated animals, as indicated by the lactate dehydrogenase levels. Taken together, these data suggest that the thiol-antioxidant, NACA, can protect the lungs from DEP-induced inflammation and oxidative stress related damage.

Impact of Alternative Fuels on Emissions Characteristics of a Gas Turbine Engine ? Part 1: Gaseous and Particulate Matter Emissions

Growing concern over emissions from increased airport operations has resulted in a need to assess the impact of aviation related activities on local air quality in and around airports, and to develop strategies to mitigate these effects. One such strategy being investigated is the use of alternative fuels in aircraft engines and auxiliary power units (APUs) as a means to diversify fuel supplies and reduce emissions. This paper summarizes the results of a study to characterize the emissions of an APU, a small gas turbine engine, burning conventional Jet A-1, a fully synthetic jet fuel, and other alternative fuels with varying compositions. Gas phase emissions were measured at the engine exit plane while PM emissions were recorded at the exit plane as well as 10 m downstream of the engine. Five percent reduction in NO(x) emissions and 5-10% reduction in CO emissions were observed for the alternative fuels. Significant reductions in PM emissions at the engine exit plane were achieved with the alternative fuels. However, as the exhaust plume expanded and cooled, organic species were found to condense on the PM. This increase in organic PM elevated the PM mass but had little impact on PM number.

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

This study reports the first of a kind data on aircraft engine non-volatile particulate matter (nvPM) number- and mass-based 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 Zürich, 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 mass-mobility 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.

Determination of the emissions from an aircraft auxiliary power unit (APU) during the Alternative Aviation Fuel Experiment (AAFEX)

The emissions from a Garrett-AiResearch (now Honeywell) Model GTCP85–98CK auxiliary power unit (APU) were determined as part of the National Aeronautics and Space Administrations (NASAs) Alternative Aviation Fuel Experiment (AAFEX) using both JP-8 and a coal-derived Fischer Tropsch fuel (FT-2). Measurements were conducted by multiple research organizations for sulfur dioxide (SO2), total hydrocarbons (THC), carbon monoxide (CO), carbon dioxide (CO2), nitrogen oxides (NOx), speciated gas-phase emissions, particulate matter (PM) mass and number, black carbon, and speciated PM. In addition, particle size distribution (PSD), number-based geometric mean particle diameter (GMD), and smoke number were also determined from the data collected. The results of the research showed PM mass emission indices (EIs) in the range of 20 to 700 mg/kg fuel and PM number EIs ranging from 0.5 × 1015 to 5 × 1015 particles/kg fuel depending on engine load and fuel type. In addition, significant reductions in both the SO2 and PM EIs were observed for the use of the FT fuel. These reductions were on the order of ∼90% for SO2 and particle mass EIs and ∼60% for the particle number EI, with similar decreases observed for black carbon. Also, the size of the particles generated by JP-8 combustion are noticeably larger than those emitted by the APU burning the FT fuel with the geometric mean diameters ranging from 20 to 50 nm depending on engine load and fuel type. Finally, both particle-bound sulfate and organics were reduced during FT-2 combustion. The PM sulfate was reduced by nearly 100% due to lack of sulfur in the fuel, with the PM organics reduced by a factor of ∼5 as compared with JP-8. Implications: The results of this research show that APUs can be, depending on the level of fuel usage, an important source of air pollutant emissions at major airports in urban areas. Substantial decreases in emissions can also be achieved through the use of Fischer Tropsch (FT) fuel. Based on these results, the use of FT fuel could be a viable future control strategy for both gas- and particle-phase air pollutants. Supplemental Data: Supplemental data is available for this article. Go to the publishers online edition of the Journal of the Air & Waste Management Association for information on the test participants, description of the APU, fuel composition, sampling probes and instrumentation, test matrix, benzene to formaldehyde ratios, and speciated emissions by particle size.

Polycyclic Aromatic Hydrocarbon Emissions from the Combustion of Alternative Fuels in a Gas Turbine Engine

We report on the particulate-bound polycyclic aromatic hydrocarbons (PAH) in the exhaust of a test-bed gas turbine engine when powered by Jet A-1 aviation fuel and a number of alternative fuels: Sasol fully synthetic jet fuel (FSJF), Shell gas-to-liquid (GTL) kerosene, and Jet A-1/GTL 50:50 blended kerosene. The concentration of PAH compounds in the exhaust emissions vary greatly between fuels. Combustion of FSJF produces the greatest total concentration of PAH compounds while combustion of GTL produces the least. However, when PAHs in the exhaust sample are measured in terms of the regulatory marker compound benzo[a]pyrene, then all of the alternative fuels emit a lower concentration of PAH in comparison to Jet A-1. Emissions from the combustion of Jet A-1/GTL blended kerosene were found to have a disproportionately low concentration of PAHs and appear to inherit a greater proportion of the GTL emission characteristics than would be expected from volume fraction alone. The data imply the presence of a nonlinear relation between fuel blend composition and the emission of PAH compounds. For each of the fuels, the speciation of PAH compounds present in the exhaust emissions were found to be remarkably similar (R(2) = 0.94-0.62), and the results do provide evidence to support the premise that PAH speciation is to some extent indicative of the emission source. In contrast, no correlation was found between the PAH species present in the fuel with those subsequently emitted in the exhaust. The results strongly suggests that local air quality measured in terms of the particulate-bound PAH burden could be significantly improved by the use of GTL kerosene either blended with or in place of Jet A-1 kerosene.

Impact of Alternative Fuels on Emissions Characteristics of a Gas Turbine Engine − Part 2: Volatile and Semivolatile Particulate Matter Emissions

The work characterizes the changes in volatile and semivolatile PM emissions from a gas turbine engine resulting from burning alternative fuels, specifically gas-to-liquid (GTL), coal-to-liquid (CTL), a blend of Jet A-1 and GTL, biodiesel, and diesel, to the standard Jet A-1. The data presented here, compares the mass spectral fingerprints of the different fuels as measured by the Aerodyne high resolution time-of-flight aerosol mass spectrometer. There were three sample points, two at the exhaust exit plane with dilution added at different locations and another probe located 10 m downstream. For emissions measured at the downstream probe when the engine was operating at high power, all fuels produced chemically similar organic PM, dominated by C(x)H(y) fragments, suggesting the presence of long chain alkanes. The second largest contribution came from C(x)H(y)O(z) fragments, possibly from carbonyls or alcohols. For the nondiesel fuels, the highest loadings of organic PM were from the downstream probe at high power. Conversely, the diesel based fuels produced more organic material at low power from one of the exit plane probes. Differences in the composition of the PM for certain fuels were observed as the engine power decreased to idle and the measurements were made closer to the exit plane.

Performance Evaluation of a Fast Mobility-Based Particle Spectrometer for Aircraft Exhaust

=cm 3 (after dilution). On average, the Dg, DgM, � g, and N of the DMS500 size distributions differed by 9, 7, 1, and 30% from the reference values of the traditional instruments. Compared with the reference values, both Dg andg of the DMS500 showed a small but statistically significant decrease with increasing particle size. Effects due to particle shape appeared to be the most likely explanation for the observed size-related trends. The 30% disagreement in concentrationmeasurementsisreasonablewhenthesensitivityofthe3022condensationparticlecountertopressure fluctuations encountered during measurements at the engine exhaust nozzle is taken into account.

Summarizing and Interpreting Aircraft Gaseous and Particulate Emissions Data

This report provides a summary of a series of government-sponsored aircraft emissions tests that were undertaken to gain a better understanding of gaseous and particulate emissions from aircraft engines. Copious amounts of data were collected as part of this scientific effort, known as the Aircraft Particle Emissions eXperiment (APEX) tests and Delta Atlanta Hartsfield test. This report summarizes the data gathered in these studies to help the airport community and general public understand how the data can be used to develop better air quality assessments in the airport environment.