Biofuel emissions

DLR/NASA flight tests on biofuel emissions

The ion trap mass spectrometer was used during a joint DLR and NASA measurement campaign in January 2018 to examine the emissions and contrails of alternative fuels. HEFA biofuel (Hydroprocessed Esters and Fatty Acids), which is derived from the oil of Camelina plants, was used as an alternative fuel. During the flight tests, which started from the air base in Ramstein/ Rhineland-Palatinate, DLR’s A320 ATRA used various blends of biofuel and kerosene, and NASA’s DC-8 research aircraft measured the emissions and contrails in the wake of ATRA. The DC-8 was equipped with NASA and DLR measurement devices.

The mass spectrometer was used during the flight to measure gas emissions, such as sulphur dioxide, and chemiions. The instrument, developed at the DLR Institute of Atmospheric Physics, chemically ionises engine gases with the help of negatively-charged CO3 ions that are generated in the instrument. The ion-molecule reactions with CO3 ions generate characteristic products that are analysed using the ion trap mass spectrometer. Already charged molecules in the exhaust stream, so-called chemiions, can be directly measured using the ion trap mass spectrometer. For extremely accurate online calibration, a small amount of isotopically labelled gases are added to the air sample, which are incorporated into the mass spectra as measurement standards. The ion trap mass spectrometer therefore enables extremely accurate measurements with a time resolution of one second.

German Aerospace Center (DLR)

Hans Schlager · E-Mail: ·