Christopher Klingshirn

Gaseous and Particulate Emissions Results of the NASA Alternative Aviation Fuel Experiment (AAFEX)

The Aircraft Alternative Fuels Emissions experiment (AAFEX) was conducted at National Aeronautic and Space Administration (NASA) Dryden Flight Research Center (DFRC) Aircraft Operations Facility (DAOF) in Palmdale, California, during January and February 2009. The purpose was to systematically investigate the effect of alternative fuels on both gas-phase and particle emissions from a CFM56-2C1 engine on NASA’s DC-8 aircraft parked on the ground as functions of engine power, fuel composition, and exhaust plume age. Emissions parameters were measured at 6 engine power settings, ranging from idle to maximum thrust, in samples collected at 1, 30, and 145 meters (m) downstream of the exhaust plane as the aircraft burned three pure fuels and two fuel blends. The fuels included JP-8, two fuels produced using the Fischer-Tropsch process and 50/50 blends by volume of the F-T fuels with JP-8. The 1 m sampling rakes contained multiple gas and particle inlet probes and could also be traversed in order to measure the spatial variation of emissions across the engine exhaust plane. The #2 inboard engine on the left side always burned JP-8 while the #3 inboard right side engine was fueled with the various fuels and fuel blends. In addition, emissions from the Auxiliary Power Unit (APU) were also evaluated with both JP-8 and one pure F-T fuel. Both gaseous and particulate emissions are presented. Results show that the synthetic fuels reduced pollutant emissions while having relatively little effect on engine operation or performance.Copyright

Hydroprocessed Renewable Jet Fuel Evaluation, Performance, and Emissions in a T63 Turbine Engine

Due to potential beneficial environmental impacts and increased supply availability, alternative fuels derived from renewable resources are evolving on the forefront as unconventional substitutes for fossil fuel. Focus is being given to the evaluation and certification of Hydroprocessed Renewable Jet (HRJ), a fuel produced from animal fat and/or plant oils (triglycerides) by hydroprocessing, as the next potential synthetic aviation fuel. Extensive efforts have recently been performed at the Air Force Research Laboratory (AFRL) at Wright Patterson Air Force Base (WPAFB) to evaluate the potential of two HRJ fuels produced from camelina and tallow feedstocks. These have included characterization of the fuel chemical, physical fuel characteristics and Fit-for-Purpose properties (FFP). The present effort describes general combustion performance and the emission propensity of a T63-A-700 Allison turbine engine operated on the HRJs and 50/50 (by volume) HRJ/JP-8 fuel blends relative to a specification JP-8. In addition, engine and emission testing with a blend of the tallow-derived HRJ and 16% bio-derived aromatic components was completed. Fundamental engine performance characterization allows for determination of the suitability of potential synthetic fuels while quantitation of gaseous and particulate matter emissions provides an assessment of the potential environmental impact compared to current petroleum-derived fuels. In addition, an extended 150 h endurance test was performed using a 50/50 blend of tallow-derived HRJ with JP-8 to evaluate the long-term operation of the engine with the synthetic fuel blend. This paper discusses the laboratory testing performed to characterize HRJs and results from the basic engine operability and emissions studies of the alternative fuel blends.

Development of methodologies for identification and quantification of hazardous air pollutants from turbine engine emissions.

Aircraft turbine engines are a significant source of particulate matter (PM) and gaseous emissions in the vicinity of airports and military installations. Hazardous air pollutants (HAPs) (e.g., formaldehyde, benzene, naphthalene and other compounds) associated with aircraft emissions are an environmental concern both in flight and at ground level. Therefore, effective sampling, identification, and accurate measurement of these trace species are important to assess their environmental impact. This effort evaluates two established ambient air sampling and analysis methods, U.S. Environmental Protection Agency (EPA) Method TO-11A and National Institute for Occupational Safety and Health (NIOSH) Method 1501, for potential use to quantify HAPs from aircraft turbine engines. The techniques were used to perform analysis of the exhaust from a T63 turboshaft engine, and were examined using certified gas standards transferred through the heated sampling systems used for engine exhaust gaseous emissions measurements. Test results show that the EPA Method TO-11A (for aldehydes) and NIOSH Method 1501 (for semivolatile hydrocarbons) were effective techniques for the sampling and analysis of most HAPs of interest. Both methods showed reasonable extraction efficiencies of HAP species from the sorbent tubes, with the exception of acrolein, styrene, and phenol, which were not well quantified. Formaldehyde measurements using dinitrophenylhydrazine (DNPH) tubes (EPA method TO-11A) were accurate for gas-phase standards, and compared favorably to measurements using gas-phase Fourier-transform infrared (FTIR) spectroscopy. In general, these two standard methodologies proved to be suitable techniques for field measurement of turbine engine HAPs within a reasonable (5–10 minutes) sampling period. Details of the tests, the analysis methods, calibration procedures, and results from the gas standards and T63 engine tested using a conventional JP-8 jet fuel are provided. Implications: HAPs from aviation-related sources are important because of their adverse health and environmental impacts in and around airports and flight lines. Simpler, more convenient techniques to measure the important HAPs, especially aldehydes and volatile organic HAPs, are needed to provide information about their occurrence and assist in the development of engines that emit fewer harmful emissions.

Comparisons of Emissions Characteristics of Several Turbine Engines Burning Fischer-Tropsch and Hydroprocessed Esters and Fatty Acids Alternative Jet Fuels

A summary of the impacts of alternative fuel blends on the gaseous and particulate matter (PM) (mostly soot) emissions of aircraft turbine engines is presented. Six engines were studied under several US Air Force and NASA sponsored programs to assess the impacts of the alternative (non-petroleum) fuels on emissions and/or to support the certification of military aircraft for the use of 50/50 (by volume) alternative fuel/JP-8 blends. One turboshaft (T63) and five turbofan (CFM56-7, CFM56-2, F117, TF33 and PW308) engines were studied. Fuels derived from coal and natural gas produced via Fischer-Tropsch (FT) synthesis, and fuels from animal fats and plant oils produced via hydroprocessing [Hydroprocessed Esters and Fatty Acids (HEFA)] were evaluated. Trends of alternative fuel impacts on emissions compared to conventional fuel for the different engine types are discussed. Results consistently show significant reductions in PM emissions with the alternative fuel blends compared to operation with conventional fuels. These relative reductions were observed to be lower as engine power increased. Engines operated with different alternative fuel blends were found to produce similar slopes of normalized particle number to engine power with only the magnitude of the reductions being a function of the fuel type. These results suggest that it may be plausible to predict particle number emissions from turbine engines operated on alternative fuels based on engine, engine setting, limited PM data and fuel composition. Gaseous emissions measurements show modest reductions of carbon monoxide, unburned hydrocarbons and hazardous air pollutants (HAPs) with the alternative fuels for several engines; however, no clear dependency of fuel impacts based on engine characteristics were observed.Copyright

Emissions Characteristics of a Legacy Military Aircraft

Emissions from aircraft and associated ground equipment are major sources of local pollution at airports and military bases. These pollutant emissions, especially particulate matter (PM), have been receiving significant attention lately due to their proven harmful health and environmental effects. As the U.S. Environmental Protection Agency (EPA) tightens environmental standards, it is likely that military operations, including the basing of advanced and legacy aircraft, will be impacted. Accurate determination of emission indices from aircraft is necessary to properly assess their environmental burden. As such, the gaseous and PM emissions of a B-52 Stratofortress aircraft were characterized in this effort. This emissions study supports the Strategic Environmental Research and Development Program (SERDP) project WP-1401 to determine emissions factors from military aircraft. The main purpose of the project is to develop a comprehensive emissions measurement program using both conventional and advanced techniques to determine emissions factors for pollutants of fixed and rotating wing military aircraft. Standard practices for the measurement of gaseous emissions from aircraft have been well established; however, there is no certified methodology for the measurement of aircraft PM emissions. In this study, several conventional aerosol instruments were employed to physically characterize the PM emissions from two of the aircraft’s TF33 turbofan engines. Exit plane pollutant emissions were extracted via probes and transported through heated lines to the analytical instruments. Particle concentrations, size distributions and mass emissions, as well as engine smoke numbers (SN), soot volatile fraction and total hydrocarbon emissions were measured. The engines were tested at four power settings, from idle to 75% normal rated thrust (NRT) (95% N2 – turbine speed). Test results show relatively consistent PM and gaseous emissions between the two engines for most conditions tested. The measured TF33 PM mass emission indices (EI), including estimated sampling line losses, were in the range of 1.0–3.0 g/kg-fuel and the particle number (PN) EI were between 4.0–10.0E+15 particles/kg-fuel. The particle size data followed a single mode lognormal distribution for all power settings with particle geometric mean diameters ranging from 52 to 85 nm. In general, the aerosol instrumentation provided consistent and reliable measurements throughout the test campaign, therefore increasing confidence on their use for turbine engine PM emissions measurements.Copyright

Hydroprocessed Renewable Jet Fuel Evaluation, Performance, and Emissions in a T-63 Turbine Engine

Due to potential beneficial environmental impacts and increased supply availability, alternative fuels derived from renewable resources are evolving on the forefront as unconventional substitutes for fossil fuel. Focus is being given to the evaluation and certification of Hydroprocessed Renewable Jet (HRJ), a fuel produced from animal fat and/or plant oils (triglycerides) by hydroprocessing, as the next potential synthetic aviation fuel. Extensive efforts have recently been performed at the Air Force Research Laboratory (AFRL) at Wright Patterson Air Force Base (WPAFB) to evaluate the potential of two HRJ fuels produced from camelina and tallow feedstocks. These have included characterization of the fuel chemical and physical fuel characteristics, and Fit-for-Purpose properties (FFP). The present effort describes general combustion performance and emission propensity of a T63-A-700 Allison turbine engine operated on the HRJs and 50/50 (by volume) HRJ/JP-8 fuel blends relative to a specification JP-8. In addition, engine and emission testing with a blend of the tallow-derived HRJ and 16% bio-derived aromatic components was completed. Fundamental engine performance characterization allows for determination of the suitability of potential synthetic fuels while quantitation of gaseous and particulate matter emissions provides an assessment of the potential environmental impact compared to current petroleum-derived fuels. In addition, an extended 150 hour endurance test was performed using a 50/50 blend of tallow-derived HRJ with JP-8 to evaluate the long-term operation of the engine with the synthetic fuel blend. This paper discusses the laboratory testing performed to characterize HRJs and results from the basic engine operability and emissions studies of the alternative fuel blends.Copyright