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Measurements of Nitrous Acid in Commercial Aircraft Exhaust at the Alternative Aviation Fuel Experiment

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journal contribution
posted on 15.09.2011, 00:00 by Ben H. Lee, Gregory W. Santoni, Ezra C. Wood, Scott C. Herndon, Richard C. Miake-Lye, Mark S. Zahniser, Steven C. Wofsy, J. William Munger
The Alternative Aviation Fuel Experiment (AAFEX), conducted in January of 2009 in Palmdale, California, quantified aerosol and gaseous emissions from a DC-8 aircraft equipped with CFM56-2C1 engines using both traditional and synthetic fuels. This study examines the emissions of nitrous acid (HONO) and nitrogen oxides (NOx = NO + NO2) measured 145 m behind the grounded aircraft. The fuel-based emission index (EI) for HONO increases approximately 6-fold from idle to takeoff conditions but plateaus between 65 and 100% of maximum rated engine thrust, while the EI for NOx increases continuously. At high engine power, NOx EI is greater when combusting traditional (JP-8) rather than Fischer–Tropsch fuels, while HONO exhibits the opposite trend. Additionally, hydrogen peroxide (H2O2) was identified in exhaust plumes emitted only during engine idle. Chemical reactions responsible for emissions and comparison to previous measurement studies are discussed.