An Instrument to Measure Aircraft Sulfate Particle Emissions

NASA applications include characterization of aircraft sulfate emissions and atmospheric particle characterization tests. Sulfate is one of the major categories of aircraft particle emissions and it plays a crucial role in determining the size distribution of particles in the evolving plume. Sulfate is an important contributor to the urban and atmospheric PM balance. NASA is spearheading efforts to encourage adoption of alternatives to petroleum jet fuel and the TILDAS-sulfate instrument can play an important role by helping to demonstrate the potential emissions reductions possible with the alternative fuels. In terms of atmospheric studies, sulfate is emitted directly from a number of anthropogenic sources (coal-fired power plants, aircraft) and formed in the atmosphere by oxidation of sulfur dioxide. Time resolved measurements of particle sulfate would permit differentiation from potential sulfate sources, crucial for better understanding and mitigation. The field of atmospheric nucleation is both active and – due to potential climate change implications – timely. An instrument capable of field deployment and simultaneous measurement of <50 nm sulfuric acid and trace gas sulfur dioxide would provide valuable information to resolve current debates on the importance of sulfuric acid and organic materials to atmospheric nucleation processes.

NASA, EPA, SERDP, U.S. Air Force, FAA, airport operators, and engine manufacturers are all aircraft particle emissions stakeholders. EPA in particular has maintained that aircraft emissions regulations must taken into account both non-volatile particle (soot) emissions and volatile (sulfate and organic) particle emissions. The FAA has been considering mandating use of lower sulfur jet fuels and the U.S. Air Force and U.S. Navy are aggressively pursuing low-sulfur synthetic fuels and synthetic fuel blends for use in their aircraft. We anticipate working with these partners to characterize particle emissions, develop better airport and Air Force base operation procedures, and design lower emissions aircraft engines and fuels. The TILDAS-sulfate instrument will be an important capability in these efforts. A primary factor in all of these is reduction of particle emissions, specifically sulfate particle emissions. Few commercial instruments are capable of providing direct measurements of sulfate particle emissions, and none of them match the specifications we are targeting for the TILDAS-sulfate instrument. Additional potential non-NASA applications include: diesel exhaust characterization, atmospheric chemistry studies, urban air quality studies, and industrial pollution characterization. Out of these applications, DOE and NOAA are specifically interested in improving understanding of anthropogenic contributions to climate change and the role of particle emissions. More »