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Exhaust Gas Analytics

The determination of chemicals and solids resulting from combustion processes is associated with high instrumental effort. Therefore, the department “Chemical Analytics” features state-of-the-art analytical techniques to analyze gases and particles in combustion exhausts. Focus lies on continuously recording instruments to monitor the dynamics of processes.  Combustion gases, such as carbon dioxide, carbon monoxide and nitrogen oxides are measured with a mobile infrared spectrometer (FTIR) down to the ppb-range. Particle emissions in the range between 2.5 nm and 10 µm can be monitored with analytical instruments that either focus on the precise size distribution of the particles or high time-resolved measurements. Determination of the soot mass of particles <100 nm is also possible at trace levels. A size-selective deposition further allows the subsequent chemical analysis of the respective aerosol.
 

The projects of the department mainly focus on stationary emission sources in the fields of energy and aviation (e.g., test environments for engines and reactor chambers, aircrafts on the ground, gas turbines, power plants, etc.). Dilution systems with different stages allow the use of the measuring instruments in a wide concentration range. For mobile measurement campaigns a variety of devices are available. These include

• Multigas FTIR Spectrometer (FTIR, MKS)
• Scanning Mobility Particle Sizer (SMPS, TSI)
• Engine Exhaust Particle Sizer (EEPS, TSI)
• High-Temperature Electrical Low Pressure Impactor (HT-ELPI+, DEKATI)
• LII 300 Soot Monitor (Artium)
• Chemiluminescence monitors for nitrogen oxides at ppb and ppm level (ecophysics)
• stand-alone Condensation Particle Counter (CPC, TSI)
• Optical Particle Counter (OPC, TSI)
• Aerosol Photoionization Mass-Spectrometer (PIMS, self-made)
• Quadrupole Residual Gas Analyzer (RGA, Hiden)

In the framework of the DLR/NASA cooperation project “ECLIF / ND-MAX” (2018) extensive measurements were carried out on the engines of the DLR research aircraft ATRA using a number of different alternative fuels. In addition, comparative measurements were carried out with numerous other measuring systems (including the North American Reference System), which provide a unique insight into the emissions of aircraft engines. In addition to aviation, measurements for ground-based traffic (including exhaust gas measurements on dynamometers) are also carried out. The department continues to study the production of test aerosols and the use of simple sensor systems for determining airborne particle concentrations.