Emissions Characteristics of a Turbine Engine and Research Combustor Burning a Fischer−Tropsch Jet Fuel

Abstract

The emissions characteristics of two combustion platforms, a T63 turboshaft engine and an atmospheric swirl-stabilized research combustor, fueled with conventional military jet fuel (JP-8), a natural-gas-derived Fischer−Tropsch synthetic jet fuel (also referred herein as synjet or FT), and blends of the two were investigated. Nonvolatile particulate matter (PM) and gaseous emissions were analyzed to assess the impacts of the aromatic- and sulfur-free synjet fuel on the combustion products of the two platforms. The engine was operated at two power settings, and the combustor at several equivalence ratios, to evaluate the emission production over a wide range of combustion temperatures. Conventional aerosol instrumentation was used to quantify particle number (PN), size, and PM mass emissions, while a Fourier Transform Infrared analyzer was used to quantify the gaseous species. Planar laser-induced fluorescence and laser-induced incandescence techniques were employed on the research combustor to study the effects of the FT fuel on the formation and oxidation of particles in the combustor primary zone. Test results show dramatic reductions in particle concentrations and mean size on both combustion platforms with the neat FT and synjet fuel blends relative to operation with JP-8. Reductions of over 90% in PN were observed on both platforms for several operating conditions with neat FT fuel. For the engine, over an 80% reduction in smoke number was observed with neat synjet relative to operation on JP-8. As expected, reductions in sulfur oxide emissions and slight increases in water vapor (measured only in the atmospheric combustor) resulted due to the sulfur-free nature and higher hydrogen-to-carbon ratio of the synthetic fuel. Minor impacts were observed for other gaseous emissions. American Society for Testing and Materials fuel specification tests showed that JP-8/synjet blends up to 50/50% by volume satisfied the JP-8 military fuel requirements and that only the minimum specific gravity requirement was not satisfied at higher synjet concentrations. Impacts of the synjet fuel on the emissions of the atmospheric combustor and the T63 engine, a comparison of emissions between the two platforms, and results of in situ laser-based measurements in the combustor reaction zone are discussed.

Measurement and Modeling of Volatile Particle Emissions from Military Aircraft

“…Total hydrocarbon analysis shows higher concentration of normal and branched compounds in the FT fuel, while the JP-8 fuel contains more cyclic compounds. The data shown in Table 4 are similar to data for other JP-8 and FT samples [9,44,45]. …”

“…Figure 21. There were large reductions in PM mass emissions when operating the engine with FT versus JP8 fuel, as has been measured previously with a T-63 engine [44]. Total PM mass emissions were reduced by more than 60% in switching from JP8 to FT fuel.…”

“…The dip immediately after photo-oxidation begins indicates that the initial SOA formed in the chamber is much less volatile than the POA or the SOA formed in the later stages of the experiment. This change in volatility is the opposite of f 44 (Figure 19b), which indicates that the low-volatility SOA formed immediately after the lights are turned on is comprised of relatively reduced compounds. As the SOA becomes more oxygenated (larger f 44 ), the MFR at 60 °C increases to around the same value as the POA.…”

“…This change in volatility is the opposite of f 44 (Figure 19b), which indicates that the low-volatility SOA formed immediately after the lights are turned on is comprised of relatively reduced compounds. As the SOA becomes more oxygenated (larger f 44 ), the MFR at 60 °C increases to around the same value as the POA. …”

Emissions of Volatile Particulate Components from Turboshaft Engines Operated with JP-8 and Fischer-Tropsch Fuels

“…The FT fuel is composed solely of iso-(82%) and normal (18%) paraffins with a distillation range similar to a typical JP-8. Details on the physical and chemical aspects of this fuel have been previously reported (Corporan et al, 2007a;2007b;DeWitt et al, 2007). Several fuel properties (e.g., heat of combustion, freeze point, and hydrogen content) were observed to be fairly similar between the two fuel types.…”